Merge branch 'development' into Atom/jromnoa/fix-asset-path-calls-to-use-new-asset-test-class

AutomatedTesting/Gem/PythonTests/Atom/TestSuite_Main.py

@@ -29,6 +29,10 @@ class TestAutomation(EditorTestSuite):
     class AtomEditorComponents_DepthOfFieldAdded(EditorSharedTest):
         from Atom.tests import hydra_AtomEditorComponents_DepthOfFieldAdded as test_module
 
+    @pytest.mark.test_case_id("C36525659")
+    class AtomEditorComponents_DiffuseProbeGridAdded(EditorSharedTest):
+        from Atom.tests import hydra_AtomEditorComponents_DiffuseProbeGridAdded as test_module
+
     @pytest.mark.test_case_id("C32078120")
     class AtomEditorComponents_DirectionalLightAdded(EditorSharedTest):
         from Atom.tests import hydra_AtomEditorComponents_DirectionalLightAdded as test_module

AutomatedTesting/Gem/PythonTests/Atom/atom_utils/atom_constants.py

@@ -116,7 +116,7 @@ class AtomComponentProperties:
         return properties[property]
 
     @staticmethod
-    def diffuse_probe(property: str = 'name') -> str:
+    def diffuse_probe_grid(property: str = 'name') -> str:
         """
         Diffuse Probe Grid component properties. Requires one of 'shapes'.
           - 'shapes' a list of supported shapes as component names.

AutomatedTesting/Gem/PythonTests/Atom/tests/hydra_AtomEditorComponents_DiffuseProbeGridAdded.py

@@ -0,0 +1,187 @@
+"""
+Copyright (c) Contributors to the Open 3D Engine Project.
+For complete copyright and license terms please see the LICENSE at the root of this distribution.
+
+SPDX-License-Identifier: Apache-2.0 OR MIT
+"""
+
+
+class Tests:
+    creation_undo = (
+        "UNDO Entity creation success",
+        "UNDO Entity creation failed")
+    creation_redo = (
+        "REDO Entity creation success",
+        "REDO Entity creation failed")
+    diffuse_probe_grid_creation = (
+        "Diffuse Probe Grid Entity successfully created",
+        "Diffuse Probe Grid Entity failed to be created")
+    diffuse_probe_grid_component = (
+        "Entity has a Diffuse Probe Grid component",
+        "Entity failed to find Diffuse Probe Grid component")
+    diffuse_probe_grid_disabled = (
+        "Diffuse Probe Grid component disabled",
+        "Diffuse Probe Grid component was not disabled")
+    diffuse_probe_grid_enabled = (
+        "Diffuse Probe Grid component enabled",
+        "Diffuse Probe Grid component was not enabled")
+    enter_game_mode = (
+        "Entered game mode",
+        "Failed to enter game mode")
+    exit_game_mode = (
+        "Exited game mode",
+        "Couldn't exit game mode")
+    is_visible = (
+        "Entity is visible",
+        "Entity was not visible")
+    is_hidden = (
+        "Entity is hidden",
+        "Entity was not hidden")
+    entity_deleted = (
+        "Entity deleted",
+        "Entity was not deleted")
+    deletion_undo = (
+        "UNDO deletion success",
+        "UNDO deletion failed")
+    deletion_redo = (
+        "REDO deletion success",
+        "REDO deletion failed")
+
+
+def AtomEditorComponents_DiffuseProbeGrid_AddedToEntity():
+    """
+    Summary:
+    Tests the Diffuse Probe Grid component can be added to an entity and has the expected functionality.
+
+    Test setup:
+    - Wait for Editor idle loop.
+    - Open the "Base" level.
+
+    Expected Behavior:
+    The component can be added, used in game mode, hidden/shown, deleted, and has accurate required components.
+    Creation and deletion undo/redo should also work.
+
+    Test Steps:
+    1) Create a Diffuse Probe Grid entity with no components.
+    2) Add a Diffuse Probe Grid component to Diffuse Probe Grid entity.
+    3) UNDO the entity creation and component addition.
+    4) REDO the entity creation and component addition.
+    5) Verify Diffuse Probe Grid component not enabled.
+    6) Add Shape component since it is required by the Diffuse Probe Grid component.
+    7) Verify Diffuse Probe Grid component is enabled.
+    8) Enter/Exit game mode.
+    9) Test IsHidden.
+    10) Test IsVisible.
+    11) Delete Diffuse Probe Grid entity.
+    12) UNDO deletion.
+    13) REDO deletion.
+    14) Look for errors.
+
+    :return: None
+    """
+
+    import azlmbr.legacy.general as general
+
+    from editor_python_test_tools.editor_entity_utils import EditorEntity
+    from editor_python_test_tools.utils import Report, Tracer, TestHelper
+    from Atom.atom_utils.atom_constants import AtomComponentProperties
+
+    with Tracer() as error_tracer:
+        # Test setup begins.
+        # Setup: Wait for Editor idle loop before executing Python hydra scripts then open "Base" level.
+        TestHelper.init_idle()
+        TestHelper.open_level("", "Base")
+
+        # Test steps begin.
+        # 1. Create a Diffuse Probe Grid entity with no components.
+        diffuse_probe_grid_entity = EditorEntity.create_editor_entity(AtomComponentProperties.diffuse_probe_grid())
+        Report.critical_result(Tests.diffuse_probe_grid_creation, diffuse_probe_grid_entity.exists())
+
+        # 2. Add a Diffuse Probe Grid component to Diffuse Probe Grid entity.
+        diffuse_probe_grid_component = diffuse_probe_grid_entity.add_component(
+            AtomComponentProperties.diffuse_probe_grid())
+        Report.critical_result(
+            Tests.diffuse_probe_grid_component,
+            diffuse_probe_grid_entity.has_component(AtomComponentProperties.diffuse_probe_grid()))
+
+        # 3. UNDO the entity creation and component addition.
+        # -> UNDO component addition.
+        general.undo()
+        # -> UNDO naming entity.
+        general.undo()
+        # -> UNDO selecting entity.
+        general.undo()
+        # -> UNDO entity creation.
+        general.undo()
+        general.idle_wait_frames(1)
+        Report.result(Tests.creation_undo, not diffuse_probe_grid_entity.exists())
+
+        # 4. REDO the entity creation and component addition.
+        # -> REDO entity creation.
+        general.redo()
+        # -> REDO selecting entity.
+        general.redo()
+        # -> REDO naming entity.
+        general.redo()
+        # -> REDO component addition.
+        general.redo()
+        general.idle_wait_frames(1)
+        Report.result(Tests.creation_redo, diffuse_probe_grid_entity.exists())
+
+        # 5. Verify Diffuse Probe Grid component not enabled.
+        Report.result(Tests.diffuse_probe_grid_disabled, not diffuse_probe_grid_component.is_enabled())
+
+        # 6. Add Shape component since it is required by the Diffuse Probe Grid component.
+        for shape in AtomComponentProperties.diffuse_probe_grid('shapes'):
+            diffuse_probe_grid_entity.add_component(shape)
+            test_shape = (
+                f"Entity has a {shape} component",
+                f"Entity did not have a {shape} component")
+            Report.result(test_shape, diffuse_probe_grid_entity.has_component(shape))
+
+            # 7. Check if required shape allows Diffuse Probe Grid to be enabled
+            Report.result(Tests.diffuse_probe_grid_enabled, diffuse_probe_grid_component.is_enabled())
+
+            # Undo to remove each added shape except the last one and verify Diffuse Probe Grid is not enabled.
+            if not (shape == AtomComponentProperties.diffuse_probe_grid('shapes')[-1]):
+                general.undo()
+                TestHelper.wait_for_condition(lambda: not diffuse_probe_grid_entity.has_component(shape), 1.0)
+                Report.result(Tests.diffuse_probe_grid_disabled, not diffuse_probe_grid_component.is_enabled())
+
+        # 8. Enter/Exit game mode.
+        TestHelper.enter_game_mode(Tests.enter_game_mode)
+        general.idle_wait_frames(1)
+        TestHelper.exit_game_mode(Tests.exit_game_mode)
+
+        # 9. Test IsHidden.
+        diffuse_probe_grid_entity.set_visibility_state(False)
+        Report.result(Tests.is_hidden, diffuse_probe_grid_entity.is_hidden() is True)
+
+        # 10. Test IsVisible.
+        diffuse_probe_grid_entity.set_visibility_state(True)
+        general.idle_wait_frames(1)
+        Report.result(Tests.is_visible, diffuse_probe_grid_entity.is_visible() is True)
+
+        # 11. Delete Diffuse Probe Grid entity.
+        diffuse_probe_grid_entity.delete()
+        Report.result(Tests.entity_deleted, not diffuse_probe_grid_entity.exists())
+
+        # 12. UNDO deletion.
+        general.undo()
+        Report.result(Tests.deletion_undo, diffuse_probe_grid_entity.exists())
+
+        # 13. REDO deletion.
+        general.redo()
+        Report.result(Tests.deletion_redo, not diffuse_probe_grid_entity.exists())
+
+        # 14. Look for errors or asserts.
+        TestHelper.wait_for_condition(lambda: error_tracer.has_errors or error_tracer.has_asserts, 1.0)
+        for error_info in error_tracer.errors:
+            Report.info(f"Error: {error_info.filename} {error_info.function} | {error_info.message}")
+        for assert_info in error_tracer.asserts:
+            Report.info(f"Assert: {assert_info.filename} {assert_info.function} | {assert_info.message}")
+
+
+if __name__ == "__main__":
+    from editor_python_test_tools.utils import Report
+    Report.start_test(AtomEditorComponents_DiffuseProbeGrid_AddedToEntity)

AutomatedTesting/Gem/PythonTests/NvCloth/tests/NvCloth_AddClothSimulationToActor.py

@@ -50,6 +50,7 @@ def NvCloth_AddClothSimulationToActor():
     
     # Constants
     FRAMES_IN_GAME_MODE = 200
+    CLOTH_GEM_ERROR_WARNING_LIST = ["Cloth", "NvCloth", "ClothComponentMesh", "ActorClothSkinning", "ActorClothSkinning", "TangentSpaceHelper", "MeshAssetHelper", "ActorAssetHelper", "ClothDebugDisplay"]
 
     helper.init_idle()
     # 1) Load the level
@@ -64,14 +65,16 @@ def NvCloth_AddClothSimulationToActor():
         general.idle_wait_frames(FRAMES_IN_GAME_MODE)
 
     # 5) Verify there are no errors and warnings in the logs
-    success_condition = not (section_tracer.has_errors or section_tracer.has_warnings)
-    Report.result(Tests.no_errors_and_warnings_found, success_condition)
-    if not success_condition:
-        if section_tracer.has_warnings:
-            Report.info(f"Warnings found: {section_tracer.warnings}")
-        if section_tracer.has_errors:
-            Report.info(f"Errors found: {section_tracer.errors}")
-        Report.failure(Tests.no_errors_and_warnings_found)
+    has_errors_or_warnings = False
+    for error_msg in section_tracer.errors:
+        if error_msg.window in CLOTH_GEM_ERROR_WARNING_LIST:
+            has_errors_or_warnings = True
+            Report.info(f"Cloth error found: {error_msg}")
+    for warning_msg in section_tracer.warnings:
+        if warning_msg.window in CLOTH_GEM_ERROR_WARNING_LIST:
+            has_errors_or_warnings = True
+            Report.info(f"Cloth warning found: {warning_msg}")
+    Report.result(Tests.no_errors_and_warnings_found, not has_errors_or_warnings)
 
     # 6) Exit game mode
     helper.exit_game_mode(Tests.exit_game_mode)

AutomatedTesting/Gem/PythonTests/NvCloth/tests/NvCloth_AddClothSimulationToMesh.py

@@ -50,6 +50,7 @@ def NvCloth_AddClothSimulationToMesh():
     
     # Constants
     FRAMES_IN_GAME_MODE = 200
+    CLOTH_GEM_ERROR_WARNING_LIST = ["Cloth", "NvCloth", "ClothComponentMesh", "ActorClothSkinning", "ActorClothSkinning", "TangentSpaceHelper", "MeshAssetHelper", "ActorAssetHelper", "ClothDebugDisplay"]
 
     helper.init_idle()
     # 1) Load the level
@@ -64,14 +65,16 @@ def NvCloth_AddClothSimulationToMesh():
         general.idle_wait_frames(FRAMES_IN_GAME_MODE)
 
     # 5) Verify there are no errors and warnings in the logs
-    success_condition = not (section_tracer.has_errors or section_tracer.has_warnings)
-    Report.result(Tests.no_errors_and_warnings_found, success_condition)
-    if not success_condition:
-        if section_tracer.has_warnings:
-            Report.info(f"Warnings found: {section_tracer.warnings}")
-        if section_tracer.has_errors:
-            Report.info(f"Errors found: {section_tracer.errors}")
-        Report.failure(Tests.no_errors_and_warnings_found)
+    has_errors_or_warnings = False
+    for error_msg in section_tracer.errors:
+        if error_msg.window in CLOTH_GEM_ERROR_WARNING_LIST:
+            has_errors_or_warnings = True
+            Report.info(f"Cloth error found: {error_msg}")
+    for warning_msg in section_tracer.warnings:
+        if warning_msg.window in CLOTH_GEM_ERROR_WARNING_LIST:
+            has_errors_or_warnings = True
+            Report.info(f"Cloth warning found: {warning_msg}")
+    Report.result(Tests.no_errors_and_warnings_found, not has_errors_or_warnings)
 
     # 6) Exit game mode
     helper.exit_game_mode(Tests.exit_game_mode)

AutomatedTesting/Gem/PythonTests/assetpipeline/ap_fixtures/bundler_batch_setup_fixture.py

@@ -158,7 +158,7 @@ def bundler_batch_setup_fixture(request, workspace, asset_processor, timeout) ->
                 else:
                     cmd.append(f"--{key}")
             if append_defaults:
-                cmd.append(f"--project-path={workspace.project}")
+                cmd.append(f"--project-path={os.path.join(workspace.paths.engine_root(), workspace.project)}")
             return cmd
 
         # ******

CMakeLists.txt

@@ -14,6 +14,7 @@ include(cmake/Version.cmake)
 include(cmake/OutputDirectory.cmake)
 
 if(NOT PROJECT_NAME)
+    include(cmake/CompilerSettings.cmake)
     project(O3DE
         LANGUAGES C CXX
         VERSION ${LY_VERSION_STRING}

Code/Editor/CMakeLists.txt

@@ -249,38 +249,9 @@ if(PAL_TRAIT_BUILD_TESTS_SUPPORTED)
         RUNTIME_DEPENDENCIES
             Gem::LmbrCentral
     )
+
     ly_add_googletest(
         NAME Legacy::EditorLib.Tests
     )
 
-    ly_add_target(
-        NAME EditorLib.Camera.Tests ${PAL_TRAIT_TEST_TARGET_TYPE}
-        NAMESPACE Legacy
-        FILES_CMAKE
-            Lib/Tests/Camera/editor_lib_camera_test_files.cmake
-        INCLUDE_DIRECTORIES
-            PRIVATE
-                .
-        BUILD_DEPENDENCIES
-            PRIVATE
-                AZ::AzCore
-                AZ::AzTest
-                AZ::AzToolsFramework
-                AZ::AzTestShared
-                Legacy::EditorLib
-                Gem::Camera.Editor
-                Gem::AtomToolsFramework.Static
-        RUNTIME_DEPENDENCIES
-            Legacy::EditorLib
-    )
-
-    ly_add_source_properties(
-        SOURCES Lib/Tests/Camera/test_EditorCamera.cpp
-        PROPERTY COMPILE_DEFINITIONS 
-        VALUES CAMERA_EDITOR_MODULE="$<TARGET_FILE_BASE_NAME:Camera.Editor>"
-    )
-
-    ly_add_googletest(
-        NAME Legacy::EditorLib.Camera.Tests
-    )
 endif()

Code/Editor/CryEdit.cpp

@@ -3827,7 +3827,8 @@ void CCryEditApp::OnOpenQuickAccessBar()
     }
 
     QRect geo = m_pQuickAccessBar->geometry();
-    geo.moveCenter(MainWindow::instance()->geometry().center());
+    auto mainWindow = MainWindow::instance();
+    geo.moveCenter(mainWindow->mapToGlobal(mainWindow->geometry().center()));
     m_pQuickAccessBar->setGeometry(geo);
     m_pQuickAccessBar->setVisible(true);
     m_pQuickAccessBar->setFocus();

Code/Editor/EditorEnvironment.cpp

@@ -17,7 +17,7 @@ void SetEditorEnvironment(SSystemGlobalEnvironment* pEnv)
 
 void AttachEditorAZEnvironment(AZ::EnvironmentInstance azEnv)
 {
-    AZ::Environment::Attach(azEnv, true);
+    AZ::Environment::Attach(azEnv);
 }
 
 void DetachEditorAZEnvironment()

Code/Editor/EditorModularViewportCameraComposer.cpp

@@ -13,9 +13,32 @@
 #include <AzCore/std/smart_ptr/make_shared.h>
 #include <AzFramework/Render/IntersectorInterface.h>
 #include <AzToolsFramework/Viewport/ViewportMessages.h>
+#include <AzToolsFramework/ViewportSelection/EditorSelectionUtil.h>
 #include <AzToolsFramework/ViewportSelection/EditorTransformComponentSelectionRequestBus.h>
 #include <EditorViewportSettings.h>
 
+AZ_CVAR(
+    bool,
+    ed_cameraPinDefaultOrbit,
+    true,
+    nullptr,
+    AZ::ConsoleFunctorFlags::Null,
+    "Sets whether the default orbit point moves with the camera or not");
+AZ_CVAR(
+    bool,
+    ed_cameraDefaultOrbitAxesOrtho,
+    true,
+    nullptr,
+    AZ::ConsoleFunctorFlags::Null,
+    "Sets whether to draw the default orbit point as orthographic or not");
+AZ_CVAR(
+    float,
+    ed_cameraDefaultOrbitFadeDuration,
+    0.5f,
+    nullptr,
+    AZ::ConsoleFunctorFlags::Null,
+    "Sets how long the default orbit point should take to appear and disappear");
+
 namespace SandboxEditor
 {
     static AzFramework::TranslateCameraInputChannelIds BuildTranslateCameraInputChannelIds()
@@ -174,7 +197,7 @@ namespace SandboxEditor
             return SandboxEditor::CameraScrollSpeed();
         };
 
-        const auto pivotFn = []
+        const auto pivotFn = []() -> AZStd::optional<AZ::Vector3>
         {
             // use the manipulator transform as the pivot point
             AZStd::optional<AZ::Transform> entityPivot;
@@ -187,8 +210,7 @@ namespace SandboxEditor
                 return entityPivot->GetTranslation();
             }
 
-            // otherwise just use the identity
-            return AZ::Vector3::CreateZero();
+            return AZStd::nullopt;
         };
 
         m_firstPersonFocusCamera =
@@ -199,9 +221,26 @@ namespace SandboxEditor
         m_orbitCamera = AZStd::make_shared<AzFramework::OrbitCameraInput>(SandboxEditor::CameraOrbitChannelId());
 
         m_orbitCamera->SetPivotFn(
-            [pivotFn]([[maybe_unused]] const AZ::Vector3& position, [[maybe_unused]] const AZ::Vector3& direction)
+            [this, pivotFn](const AZ::Vector3& position, const AZ::Vector3& direction)
             {
-                return pivotFn();
+                // return the pivot
+                if (auto pivot = pivotFn())
+                {
+                    return pivot.value();
+                }
+
+                // start ticking and drawing (for the default pivot)
+                AZ::TickBus::Handler::BusConnect();
+                AzFramework::ViewportDebugDisplayEventBus::Handler::BusConnect(AzToolsFramework::GetEntityContextId());
+
+                m_defaultOrbiting = true;
+                // calculate the default orbit point
+                if (!ed_cameraPinDefaultOrbit || m_orbitCamera->Beginning())
+                {
+                    m_defaultOrbitPoint = position + direction * SandboxEditor::CameraDefaultOrbitDistance();
+                }
+
+                return m_defaultOrbitPoint;
             });
 
         m_orbitRotateCamera = AZStd::make_shared<AzFramework::RotateCameraInput>(SandboxEditor::CameraOrbitLookChannelId());
@@ -306,4 +345,67 @@ namespace SandboxEditor
                 m_viewportId, &AtomToolsFramework::ModularViewportCameraControllerRequestBus::Events::ClearReferenceFrame);
         }
     }
+
+    void EditorModularViewportCameraComposer::OnTick(const float deltaTime, [[maybe_unused]] AZ::ScriptTimePoint time)
+    {
+        const float delta = [duration = &ed_cameraDefaultOrbitFadeDuration, deltaTime] {
+            if (*duration == 0.0f) {
+                return 1.0f;
+            }
+            return deltaTime / *duration;
+        }();
+
+        if (m_defaultOrbiting)
+        {
+            m_defaultOrbitOpacity = AZStd::min(m_defaultOrbitOpacity + delta, 1.0f);
+        }
+        else
+        {
+            m_defaultOrbitOpacity = AZStd::max(m_defaultOrbitOpacity - delta, 0.0f);
+            if (m_defaultOrbitOpacity == 0.0f)
+            {
+                AZ::TickBus::Handler::BusDisconnect();
+                AzFramework::ViewportDebugDisplayEventBus::Handler::BusDisconnect();
+            }
+        }
+
+        m_defaultOrbiting = false;
+    }
+
+    static void DrawTransformAxis(
+        AzFramework::DebugDisplayRequests& display,
+        const AzFramework::CameraState& cameraState,
+        const AZ::Vector3& pivot,
+        const float axisLength,
+        const float alpha)
+    {
+        const int prevState = display.GetState();
+
+        display.DepthWriteOff();
+        display.DepthTestOff();
+        display.CullOff();
+
+        const float orthoScale =
+            ed_cameraDefaultOrbitAxesOrtho ? AzToolsFramework::CalculateScreenToWorldMultiplier(pivot, cameraState) : 1.0f;
+
+        display.SetColor(AZ::Color::CreateFromVector3AndFloat(AZ::Colors::Red.GetAsVector3(), alpha));
+        display.DrawLine(pivot, pivot + AZ::Vector3::CreateAxisX() * axisLength * orthoScale);
+        display.SetColor(AZ::Color::CreateFromVector3AndFloat(AZ::Colors::LawnGreen.GetAsVector3(), alpha));
+        display.DrawLine(pivot, pivot + AZ::Vector3::CreateAxisY() * axisLength * orthoScale);
+        display.SetColor(AZ::Color::CreateFromVector3AndFloat(AZ::Colors::Blue.GetAsVector3(), alpha));
+        display.DrawLine(pivot, pivot + AZ::Vector3::CreateAxisZ() * axisLength * orthoScale);
+
+        display.DepthWriteOn();
+        display.DepthTestOn();
+        display.CullOn();
+
+        display.SetState(prevState);
+    }
+
+    void EditorModularViewportCameraComposer::DisplayViewport(
+        [[maybe_unused]] const AzFramework::ViewportInfo& viewportInfo, AzFramework::DebugDisplayRequests& debugDisplay)
+    {
+        DrawTransformAxis(
+            debugDisplay, AzToolsFramework::GetCameraState(viewportInfo.m_viewportId), m_defaultOrbitPoint, 1.0f, m_defaultOrbitOpacity);
+    }
 } // namespace SandboxEditor

Code/Editor/EditorModularViewportCameraComposer.h

@@ -9,6 +9,8 @@
 #pragma once
 
 #include <AtomToolsFramework/Viewport/ModularViewportCameraController.h>
+#include <AzCore/Component/TickBus.h>
+#include <AzFramework/Entity/EntityDebugDisplayBus.h>
 #include <AzFramework/Viewport/CameraInput.h>
 #include <AzToolsFramework/API/EditorCameraBus.h>
 #include <EditorModularViewportCameraComposerBus.h>
@@ -20,6 +22,8 @@ namespace SandboxEditor
     class EditorModularViewportCameraComposer
         : private EditorModularViewportCameraComposerNotificationBus::Handler
         , private Camera::EditorCameraNotificationBus::Handler
+        , private AzFramework::ViewportDebugDisplayEventBus::Handler
+        , private AZ::TickBus::Handler
     {
     public:
         SANDBOX_API explicit EditorModularViewportCameraComposer(AzFramework::ViewportId viewportId);
@@ -29,6 +33,12 @@ namespace SandboxEditor
         SANDBOX_API AZStd::shared_ptr<AtomToolsFramework::ModularViewportCameraController> CreateModularViewportCameraController();
 
     private:
+        // AzFramework::ViewportDebugDisplayEventBus overrides ...
+        void DisplayViewport(const AzFramework::ViewportInfo& viewportInfo, AzFramework::DebugDisplayRequests& debugDisplay) override;
+
+        // AZ::TickBus overrides ...
+        void OnTick(float deltaTime, AZ::ScriptTimePoint time) override;
+
         //! Setup all internal camera inputs.
         void SetupCameras();
 
@@ -52,5 +62,9 @@ namespace SandboxEditor
         AZStd::shared_ptr<AzFramework::FocusCameraInput> m_orbitFocusCamera;
 
         AzFramework::ViewportId m_viewportId;
+
+        float m_defaultOrbitOpacity = 0.0f; //!< The default orbit axes opacity (to fade in and out).
+        AZ::Vector3 m_defaultOrbitPoint = AZ::Vector3::CreateZero(); //!< The orbit point to use when no entity is selected.
+        bool m_defaultOrbiting = false; //!< Is the camera default orbiting (orbiting when there's no selected entity).
     };
 } // namespace SandboxEditor

Code/Editor/EditorPreferencesPageViewportCamera.cpp

@@ -61,7 +61,7 @@ static AZStd::vector<AZStd::string> GetEditorInputNames()
 void CEditorPreferencesPage_ViewportCamera::Reflect(AZ::SerializeContext& serialize)
 {
     serialize.Class<CameraMovementSettings>()
-        ->Version(3)
+        ->Version(4)
         ->Field("TranslateSpeed", &CameraMovementSettings::m_translateSpeed)
         ->Field("RotateSpeed", &CameraMovementSettings::m_rotateSpeed)
         ->Field("BoostMultiplier", &CameraMovementSettings::m_boostMultiplier)
@@ -76,9 +76,8 @@ void CEditorPreferencesPage_ViewportCamera::Reflect(AZ::SerializeContext& serial
         ->Field("OrbitYawRotationInverted", &CameraMovementSettings::m_orbitYawRotationInverted)
         ->Field("PanInvertedX", &CameraMovementSettings::m_panInvertedX)
         ->Field("PanInvertedY", &CameraMovementSettings::m_panInvertedY)
-        ->Field("DefaultPositionX", &CameraMovementSettings::m_defaultCameraPositionX)
-        ->Field("DefaultPositionY", &CameraMovementSettings::m_defaultCameraPositionY)
-        ->Field("DefaultPositionZ", &CameraMovementSettings::m_defaultCameraPositionZ);
+        ->Field("DefaultPosition", &CameraMovementSettings::m_defaultPosition)
+        ->Field("DefaultOrbitDistance", &CameraMovementSettings::m_defaultOrbitDistance);
 
     serialize.Class<CameraInputSettings>()
         ->Version(2)
@@ -159,14 +158,12 @@ void CEditorPreferencesPage_ViewportCamera::Reflect(AZ::SerializeContext& serial
                 AZ::Edit::UIHandlers::CheckBox, &CameraMovementSettings::m_captureCursorLook, "Camera Capture Look Cursor",
                 "Should the cursor be captured (hidden) while performing free look")
             ->DataElement(
-                AZ::Edit::UIHandlers::SpinBox, &CameraMovementSettings::m_defaultCameraPositionX, "Default X Camera Position",
-                "Default X Camera Position when a level is opened")
+                AZ::Edit::UIHandlers::Vector3, &CameraMovementSettings::m_defaultPosition, "Default Camera Position",
+                "Default Camera Position when a level is first opened")
             ->DataElement(
-                AZ::Edit::UIHandlers::SpinBox, &CameraMovementSettings::m_defaultCameraPositionY, "Default Y Camera Position",
-                "Default Y Camera Position when a level is opened")
-            ->DataElement(
-                AZ::Edit::UIHandlers::SpinBox, &CameraMovementSettings::m_defaultCameraPositionZ, "Default Z Camera Position",
-                "Default Z Camera Position when a level is opened");
+                AZ::Edit::UIHandlers::SpinBox, &CameraMovementSettings::m_defaultOrbitDistance, "Default Orbit Distance",
+                "The default distance to orbit about when there is no entity selected")
+            ->Attribute(AZ::Edit::Attributes::Min, minValue);
 
         editContext->Class<CameraInputSettings>("Camera Input Settings", "")
             ->DataElement(
@@ -283,12 +280,8 @@ void CEditorPreferencesPage_ViewportCamera::OnApply()
     SandboxEditor::SetCameraOrbitYawRotationInverted(m_cameraMovementSettings.m_orbitYawRotationInverted);
     SandboxEditor::SetCameraPanInvertedX(m_cameraMovementSettings.m_panInvertedX);
     SandboxEditor::SetCameraPanInvertedY(m_cameraMovementSettings.m_panInvertedY);
-    SandboxEditor::SetDefaultCameraEditorPosition(
-        AZ::Vector3(
-            m_cameraMovementSettings.m_defaultCameraPositionX,
-            m_cameraMovementSettings.m_defaultCameraPositionY,
-            m_cameraMovementSettings.m_defaultCameraPositionZ
-        ));
+    SandboxEditor::SetCameraDefaultEditorPosition(m_cameraMovementSettings.m_defaultPosition);
+    SandboxEditor::SetCameraDefaultOrbitDistance(m_cameraMovementSettings.m_defaultOrbitDistance);
 
     SandboxEditor::SetCameraTranslateForwardChannelId(m_cameraInputSettings.m_translateForwardChannelId);
     SandboxEditor::SetCameraTranslateBackwardChannelId(m_cameraInputSettings.m_translateBackwardChannelId);
@@ -325,11 +318,8 @@ void CEditorPreferencesPage_ViewportCamera::InitializeSettings()
     m_cameraMovementSettings.m_orbitYawRotationInverted = SandboxEditor::CameraOrbitYawRotationInverted();
     m_cameraMovementSettings.m_panInvertedX = SandboxEditor::CameraPanInvertedX();
     m_cameraMovementSettings.m_panInvertedY = SandboxEditor::CameraPanInvertedY();
-
-    AZ::Vector3 defaultCameraPosition = SandboxEditor::DefaultEditorCameraPosition();
-    m_cameraMovementSettings.m_defaultCameraPositionX = defaultCameraPosition.GetX();
-    m_cameraMovementSettings.m_defaultCameraPositionY = defaultCameraPosition.GetY();
-    m_cameraMovementSettings.m_defaultCameraPositionZ = defaultCameraPosition.GetZ();
+    m_cameraMovementSettings.m_defaultPosition = SandboxEditor::CameraDefaultEditorPosition();
+    m_cameraMovementSettings.m_defaultOrbitDistance = SandboxEditor::CameraDefaultOrbitDistance();
 
     m_cameraInputSettings.m_translateForwardChannelId = SandboxEditor::CameraTranslateForwardChannelId().GetName();
     m_cameraInputSettings.m_translateBackwardChannelId = SandboxEditor::CameraTranslateBackwardChannelId().GetName();

Code/Editor/EditorPreferencesPageViewportCamera.h

@@ -9,9 +9,12 @@
 #pragma once
 
 #include "Include/IPreferencesPage.h"
+
+#include <AzCore/Math/Vector3.h>
 #include <AzCore/RTTI/RTTI.h>
 #include <AzCore/Serialization/EditContext.h>
 #include <AzCore/Serialization/SerializeContext.h>
+
 #include <QIcon>
 
 inline AZ::Crc32 EditorPropertyVisibility(const bool enabled)
@@ -43,6 +46,7 @@ private:
     {
         AZ_TYPE_INFO(CameraMovementSettings, "{60B8C07E-5F48-4171-A50B-F45558B5CCA1}")
 
+        AZ::Vector3 m_defaultPosition;
         float m_translateSpeed;
         float m_rotateSpeed;
         float m_scrollSpeed;
@@ -50,16 +54,14 @@ private:
         float m_panSpeed;
         float m_boostMultiplier;
         float m_rotateSmoothness;
-        bool m_rotateSmoothing;
         float m_translateSmoothness;
-        bool m_translateSmoothing;
+        float m_defaultOrbitDistance;
         bool m_captureCursorLook;
         bool m_orbitYawRotationInverted;
         bool m_panInvertedX;
         bool m_panInvertedY;
-        float m_defaultCameraPositionX;
-        float m_defaultCameraPositionY;
-        float m_defaultCameraPositionZ;
+        bool m_rotateSmoothing;
+        bool m_translateSmoothing;
 
         AZ::Crc32 RotateSmoothingVisibility() const
         {

Code/Editor/EditorViewportSettings.cpp

@@ -38,6 +38,7 @@ namespace SandboxEditor
     constexpr AZStd::string_view CameraTranslateSmoothingSetting = "/Amazon/Preferences/Editor/Camera/TranslateSmoothing";
     constexpr AZStd::string_view CameraRotateSmoothingSetting = "/Amazon/Preferences/Editor/Camera/RotateSmoothing";
     constexpr AZStd::string_view CameraCaptureCursorLookSetting = "/Amazon/Preferences/Editor/Camera/CaptureCursorLook";
+    constexpr AZStd::string_view CameraDefaultOrbitDistanceSetting = "/Amazon/Preferences/Editor/Camera/DefaultOrbitDistance";
     constexpr AZStd::string_view CameraTranslateForwardIdSetting = "/Amazon/Preferences/Editor/Camera/CameraTranslateForwardId";
     constexpr AZStd::string_view CameraTranslateBackwardIdSetting = "/Amazon/Preferences/Editor/Camera/CameraTranslateBackwardId";
     constexpr AZStd::string_view CameraTranslateLeftIdSetting = "/Amazon/Preferences/Editor/Camera/CameraTranslateLeftId";
@@ -114,15 +115,15 @@ namespace SandboxEditor
         return AZStd::make_unique<EditorViewportSettingsCallbacksImpl>();
     }
 
-    AZ::Vector3 DefaultEditorCameraPosition()
+    AZ::Vector3 CameraDefaultEditorPosition()
     {
-        float xPosition = aznumeric_cast<float>(GetRegistry(CameraDefaultStartingPositionX, 0.0));
-        float yPosition = aznumeric_cast<float>(GetRegistry(CameraDefaultStartingPositionY, -10.0));
-        float zPosition = aznumeric_cast<float>(GetRegistry(CameraDefaultStartingPositionZ, 4.0));
-        return AZ::Vector3(xPosition, yPosition, zPosition);
+        return AZ::Vector3(
+            aznumeric_cast<float>(GetRegistry(CameraDefaultStartingPositionX, 0.0)),
+            aznumeric_cast<float>(GetRegistry(CameraDefaultStartingPositionY, -10.0)),
+            aznumeric_cast<float>(GetRegistry(CameraDefaultStartingPositionZ, 4.0)));
     }
 
-    void SetDefaultCameraEditorPosition(const AZ::Vector3 defaultCameraPosition)
+    void SetCameraDefaultEditorPosition(const AZ::Vector3& defaultCameraPosition)
     {
         SetRegistry(CameraDefaultStartingPositionX, defaultCameraPosition.GetX());
         SetRegistry(CameraDefaultStartingPositionY, defaultCameraPosition.GetY());
@@ -359,6 +360,16 @@ namespace SandboxEditor
         SetRegistry(CameraCaptureCursorLookSetting, capture);
     }
 
+    float CameraDefaultOrbitDistance()
+    {
+        return aznumeric_cast<float>(GetRegistry(CameraDefaultOrbitDistanceSetting, 20.0));
+    }
+
+    void SetCameraDefaultOrbitDistance(const float distance)
+    {
+        SetRegistry(CameraDefaultOrbitDistanceSetting, distance);
+    }
+
     AzFramework::InputChannelId CameraTranslateForwardChannelId()
     {
         return AzFramework::InputChannelId(

Code/Editor/EditorViewportSettings.h

@@ -33,9 +33,6 @@ namespace SandboxEditor
     //! event will fire when a value in the settings registry (editorpreferences.setreg) is modified.
     SANDBOX_API AZStd::unique_ptr<EditorViewportSettingsCallbacks> CreateEditorViewportSettingsCallbacks();
 
-    SANDBOX_API AZ::Vector3 DefaultEditorCameraPosition();
-    SANDBOX_API void SetDefaultCameraEditorPosition(AZ::Vector3 defaultCameraPosition);
-
     SANDBOX_API AZ::u64 MaxItemsShownInAssetBrowserSearch();
     SANDBOX_API void SetMaxItemsShownInAssetBrowserSearch(AZ::u64 numberOfItemsShown);
 
@@ -105,6 +102,12 @@ namespace SandboxEditor
     SANDBOX_API bool CameraCaptureCursorForLook();
     SANDBOX_API void SetCameraCaptureCursorForLook(bool capture);
 
+    SANDBOX_API AZ::Vector3 CameraDefaultEditorPosition();
+    SANDBOX_API void SetCameraDefaultEditorPosition(const AZ::Vector3& position);
+
+    SANDBOX_API float CameraDefaultOrbitDistance();
+    SANDBOX_API void SetCameraDefaultOrbitDistance(float distance);
+
     SANDBOX_API AzFramework::InputChannelId CameraTranslateForwardChannelId();
     SANDBOX_API void SetCameraTranslateForwardChannelId(AZStd::string_view cameraTranslateForwardId);
 

Code/Editor/EditorViewportWidget.cpp

@@ -620,9 +620,9 @@ void EditorViewportWidget::OnEditorNotifyEvent(EEditorNotifyEvent event)
         break;
 
     case eNotify_OnEndNewScene:
-        PopDisableRendering();
-
         {
+            PopDisableRendering();
+
             Matrix34 viewTM;
             viewTM.SetIdentity();
 
@@ -638,9 +638,9 @@ void EditorViewportWidget::OnEditorNotifyEvent(EEditorNotifyEvent event)
         break;
 
     case eNotify_OnEndTerrainCreate:
-        PopDisableRendering();
-
         {
+            PopDisableRendering();
+
             Matrix34 viewTM;
             viewTM.SetIdentity();
 
@@ -2021,10 +2021,6 @@ void EditorViewportWidget::SetDefaultCamera()
     GetViewManager()->SetCameraObjectId(GUID_NULL);
     SetName(m_defaultViewName);
 
-    // Set the default Editor Camera position.
-    m_defaultViewTM.SetTranslation(Vec3(m_editorViewportSettings.DefaultEditorCameraPosition()));
-    SetViewTM(m_defaultViewTM);
-
     // Synchronize the configured editor viewport FOV to the default camera
     if (m_viewPane)
     {
@@ -2041,6 +2037,10 @@ void EditorViewportWidget::SetDefaultCamera()
         atomViewportRequests->PushView(contextName, m_defaultView);
     }
 
+    // Set the default Editor Camera position.
+    m_defaultViewTM.SetTranslation(Vec3(m_editorViewportSettings.DefaultEditorCameraPosition()));
+    SetViewTM(m_defaultViewTM);
+
     PostCameraSet();
 }
 
@@ -2527,7 +2527,7 @@ bool EditorViewportSettings::StickySelectEnabled() const
 
 AZ::Vector3 EditorViewportSettings::DefaultEditorCameraPosition() const
 {
-    return SandboxEditor::DefaultEditorCameraPosition();
+    return SandboxEditor::CameraDefaultEditorPosition();
 }
 
 AZ_CVAR_EXTERNED(bool, ed_previewGameInFullscreen_once);

Code/Editor/GameEngine.cpp

@@ -49,9 +49,6 @@
 #include "Include/IObjectManager.h"
 #include "ActionManager.h"
 
-// Including this too early will result in a linker error
-#include <CryCommon/CryLibrary.h>
-
 // Implementation of System Callback structure.
 struct SSystemUserCallback
     : public ISystemUserCallback
@@ -242,8 +239,7 @@ private:
 
 AZ_PUSH_DISABLE_WARNING(4273, "-Wunknown-warning-option")
 CGameEngine::CGameEngine()
-    : m_gameDll(nullptr)
-    , m_bIgnoreUpdates(false)
+    : m_bIgnoreUpdates(false)
     , m_ePendingGameMode(ePGM_NotPending)
     , m_modalWindowDismisser(nullptr)
 AZ_POP_DISABLE_WARNING
@@ -253,7 +249,7 @@ AZ_POP_DISABLE_WARNING
     m_bInGameMode = false;
     m_bSimulationMode = false;
     m_bSyncPlayerPosition = true;
-    m_hSystemHandle = nullptr;
+    m_hSystemHandle.reset(nullptr);
     m_bJustCreated = false;
     m_levelName = "Untitled";
     m_levelExtension = EditorUtils::LevelFile::GetDefaultFileExtension();
@@ -268,18 +264,10 @@ AZ_POP_DISABLE_WARNING
     GetIEditor()->UnregisterNotifyListener(this);
     m_pISystem->GetIMovieSystem()->SetCallback(nullptr);
 
-    if (m_gameDll)
-    {
-        CryFreeLibrary(m_gameDll);
-    }
-
     delete m_pISystem;
     m_pISystem = nullptr;
 
-    if (m_hSystemHandle)
-    {
-        CryFreeLibrary(m_hSystemHandle);
-    }
+    m_hSystemHandle.reset(nullptr);
 
     delete m_pSystemUserCallback;
 }
@@ -347,18 +335,19 @@ AZ::Outcome<void, AZStd::string> CGameEngine::Init(
     HWND hwndForInputSystem)
 {
     m_pSystemUserCallback = new SSystemUserCallback(logo);
-    m_hSystemHandle = CryLoadLibraryDefName("CrySystem");
 
-    if (!m_hSystemHandle)
+    constexpr const char* crySystemLibraryName = AZ_TRAIT_OS_DYNAMIC_LIBRARY_PREFIX  "CrySystem" AZ_TRAIT_OS_DYNAMIC_LIBRARY_EXTENSION;
+
+    m_hSystemHandle = AZ::DynamicModuleHandle::Create(crySystemLibraryName);
+    if (!m_hSystemHandle->Load(true))
     {
-        auto errorMessage = AZStd::string::format("%s Loading Failed", CryLibraryDefName("CrySystem"));
+        auto errorMessage = AZStd::string::format("%s Loading Failed", crySystemLibraryName);
         Error(errorMessage.c_str());
         return AZ::Failure(errorMessage);
     }
 
     PFNCREATESYSTEMINTERFACE pfnCreateSystemInterface =
-        (PFNCREATESYSTEMINTERFACE)CryGetProcAddress(m_hSystemHandle, "CreateSystemInterface");
-
+        m_hSystemHandle->GetFunction<PFNCREATESYSTEMINTERFACE>("CreateSystemInterface");
 
     SSystemInitParams sip;
 

Code/Editor/GameEngine.h

@@ -28,6 +28,8 @@ struct IInitializeUIInfo;
 #include <AzCore/Interface/Interface.h>
 #include <AzCore/Math/Vector3.h>
 
+#include <AzCore/Module/DynamicModuleHandle.h>
+
 class ThreadedOnErrorHandler : public QObject
 {
     Q_OBJECT
@@ -124,11 +126,6 @@ public:
         return s_pakModifyMutex;
     }
 
-    inline HMODULE GetGameModule() const
-    {
-        return m_gameDll;
-    }
-
 private:
     void SetGameMode(bool inGame);
     void SwitchToInGame();
@@ -150,8 +147,7 @@ private:
     AZ_PUSH_DISABLE_DLL_EXPORT_MEMBER_WARNING
     Matrix34 m_playerViewTM;
     struct SSystemUserCallback* m_pSystemUserCallback;
-    HMODULE m_hSystemHandle;
-    HMODULE m_gameDll;
+    AZStd::unique_ptr<AZ::DynamicModuleHandle> m_hSystemHandle;
     enum EPendingGameMode
     {
         ePGM_NotPending,

Code/Editor/Lib/Tests/Camera/editor_lib_camera_test_files.cmake

@@ -1,11 +0,0 @@
-#
-# Copyright (c) Contributors to the Open 3D Engine Project.
-# For complete copyright and license terms please see the LICENSE at the root of this distribution.
-#
-# SPDX-License-Identifier: Apache-2.0 OR MIT
-#
-#
-
-set(FILES
-    test_EditorCamera.cpp
-)

Code/Editor/Lib/Tests/Camera/test_EditorCamera.cpp

@@ -17,43 +17,33 @@
 
 namespace UnitTest
 {
-    class EditorCameraTestEnvironment : public AZ::Test::GemTestEnvironment
-    {
-        // AZ::Test::GemTestEnvironment overrides ...
-        void AddGemsAndComponents() override;
-    };
-
-    void EditorCameraTestEnvironment::AddGemsAndComponents()
-    {
-        AddDynamicModulePaths({ CAMERA_EDITOR_MODULE });
-        AddComponentDescriptors({ AzToolsFramework::Components::TransformComponent::CreateDescriptor() });
-    }
-
     class EditorCameraFixture : public ::testing::Test
     {
     public:
+        AZ::ComponentApplication* m_application = nullptr;
         AtomToolsFramework::ModularCameraViewportContext* m_cameraViewportContextView = nullptr;
         AZStd::unique_ptr<SandboxEditor::EditorModularViewportCameraComposer> m_editorModularViewportCameraComposer;
-        AZStd::unique_ptr<AZ::DynamicModuleHandle> m_editorLibHandle;
         AzFramework::ViewportControllerListPtr m_controllerList;
-        AZStd::unique_ptr<AZ::Entity> m_entity;
+        AZ::Entity* m_entity = nullptr;
+        AZ::ComponentDescriptor* m_transformComponent = nullptr;
 
         static const AzFramework::ViewportId TestViewportId;
 
         void SetUp() override
         {
-            m_editorLibHandle = AZ::DynamicModuleHandle::Create("EditorLib");
-            [[maybe_unused]] const bool loaded = m_editorLibHandle->Load(true);
-            AZ_Assert(loaded, "EditorLib could not be loaded");
+            m_application = aznew AZ::ComponentApplication;
+            AZ::ComponentApplication::Descriptor appDesc;
+            m_entity = m_application->Create(appDesc);
+            m_transformComponent = AzToolsFramework::Components::TransformComponent::CreateDescriptor();
+            m_application->RegisterComponentDescriptor(m_transformComponent);
 
-            m_controllerList = AZStd::make_shared<AzFramework::ViewportControllerList>();
-            m_controllerList->RegisterViewportContext(TestViewportId);
-
-            m_entity = AZStd::make_unique<AZ::Entity>();
             m_entity->Init();
             m_entity->CreateComponent<AzToolsFramework::Components::TransformComponent>();
             m_entity->Activate();
 
+            m_controllerList = AZStd::make_shared<AzFramework::ViewportControllerList>();
+            m_controllerList->RegisterViewportContext(TestViewportId);
+
             m_editorModularViewportCameraComposer = AZStd::make_unique<SandboxEditor::EditorModularViewportCameraComposer>(TestViewportId);
 
             auto controller = m_editorModularViewportCameraComposer->CreateModularViewportCameraController();
@@ -72,8 +62,17 @@ namespace UnitTest
         {
             m_editorModularViewportCameraComposer.reset();
             m_cameraViewportContextView = nullptr;
-            m_entity.reset();
-            m_editorLibHandle = {};
+
+            if (m_application)
+            {
+                m_application->UnregisterComponentDescriptor(m_transformComponent);
+                delete m_transformComponent;
+                m_transformComponent = nullptr;
+
+                m_application->Destroy();
+                delete m_application;
+                m_application = nullptr;
+            }
         }
     };
 
@@ -211,15 +210,3 @@ namespace UnitTest
         EXPECT_THAT(currentReferenceFrame, IsClose(AZ::Transform::CreateIdentity()));
     }
 } // namespace UnitTest
-
-// required to support running integration tests with the Camera Gem
-AZTEST_EXPORT int AZ_UNIT_TEST_HOOK_NAME(int argc, char** argv)
-{
-    ::testing::InitGoogleMock(&argc, argv);
-    AZ::Test::printUnusedParametersWarning(argc, argv);
-    AZ::Test::addTestEnvironments({ new UnitTest::EditorCameraTestEnvironment() });
-    int result = RUN_ALL_TESTS();
-    return result;
-}
-
-IMPLEMENT_TEST_EXECUTABLE_MAIN();

Code/Editor/Lib/Tests/test_Main.cpp

@@ -9,12 +9,13 @@
 #include "EditorDefs.h"
 #include <AzTest/AzTest.h>
 #include <AzCore/Memory/SystemAllocator.h>
+#include <AzCore/UnitTest/UnitTest.h>
 #include <EditorEnvironment.h>
 
 #include <QApplication>
 
 class EditorLibTestEnvironment
-    : public AZ::Test::ITestEnvironment
+    : public ::UnitTest::TraceBusHook
 {
 public:
     ~EditorLibTestEnvironment() override = default;
@@ -22,16 +23,20 @@ public:
 protected:
     void SetupEnvironment() override
     {
+        ::UnitTest::TraceBusHook::SetupEnvironment();
+
         AZ::Environment::Create(nullptr);
-        AttachEditorAZEnvironment(AZ::Environment::GetInstance());
         AZ::AllocatorInstance<AZ::SystemAllocator>::Create();
+        AttachEditorAZEnvironment(AZ::Environment::GetInstance());
     }
 
     void TeardownEnvironment() override
     {
-        AZ::AllocatorInstance<AZ::SystemAllocator>::Destroy();
         DetachEditorAZEnvironment();
+        AZ::AllocatorInstance<AZ::SystemAllocator>::Destroy();
         AZ::Environment::Destroy();
+
+        ::UnitTest::TraceBusHook::TeardownEnvironment();
     }
 };
 

Code/Editor/LyViewPaneNames.h

@@ -44,7 +44,7 @@ namespace LyViewPane
     static const char* const SubstanceEditor = "Substance Editor";
     static const char* const VegetationEditor = "Vegetation Editor";
     static const char* const LandscapeCanvas = "Landscape Canvas";
-    static const char* const AnimationEditor = "EMotion FX Animation Editor (PREVIEW)";
+    static const char* const AnimationEditor = "EMotion FX Animation Editor";
     static const char* const PhysXConfigurationEditor = "PhysX Configuration (PREVIEW)";
 
     static const char* const SliceRelationships = "Slice Relationship View (PREVIEW)";

Code/Editor/MainStatusBar.cpp

@@ -27,7 +27,6 @@
 
 // Editor
 #include "MainStatusBarItems.h"
-#include "CryLibrary.h"
 #include "ProcessInfo.h"
 
 

Code/Editor/MainWindow.cpp

@@ -1061,7 +1061,7 @@ void MainWindow::InitActions()
     if (emfxEnabled.value)
     {
         QAction* action = am->AddAction(ID_OPEN_EMOTIONFX_EDITOR, tr("Animation Editor"))
-            .SetToolTip(tr("Open Animation Editor (PREVIEW)"))
+            .SetToolTip(tr("Open Animation Editor"))
             .SetIcon(QIcon(":/EMotionFX/EMFX_icon_32x32.png"))
             .SetApplyHoverEffect();
         QObject::connect(action, &QAction::triggered, this, []() {

Code/Editor/editor_lib_test_files.cmake

@@ -22,6 +22,7 @@ set(FILES
     Lib/Tests/test_DisplaySettingsPythonBindings.cpp
     Lib/Tests/test_ViewportManipulatorController.cpp
     Lib/Tests/test_ModularViewportCameraController.cpp
+    Lib/Tests/Camera/test_EditorCamera.cpp
     DisplaySettingsPythonFuncs.cpp
     DisplaySettingsPythonFuncs.h
 )

Code/Framework/AzCore/AzCore/Asset/AssetDataStream.h

@@ -70,6 +70,9 @@ namespace AZ::Data
 
         const char* GetFilename() const override { return m_filePath.c_str(); }
 
+        AZStd::chrono::milliseconds GetStreamingDeadline() const { return m_curDeadline; }
+        AZ::IO::IStreamerTypes::Priority GetStreamingPriority() const { return m_curPriority; }
+
         // AssetDataStream specific APIs
 
         //! Whether or not all data has been loaded.

Code/Framework/AzCore/AzCore/Script/ScriptContext.cpp

@@ -3408,7 +3408,14 @@ LUA_API const Node* lua_getDummyNode()
                     const BehaviorParameter* arg = method->GetArgument(iArg);
                     BehaviorClass* argClass = nullptr;
                     LuaLoadFromStack fromStack = FromLuaStack(context, arg, argClass);
-                    AZ_Assert(fromStack, "Argument %s for Method %s doesn't have support to be converted to Lua!", arg->m_name, method->m_name.c_str());
+                    AZ_Assert(fromStack,
+                        "The argument type: %s for method: %s is not serialized and/or reflected for scripting.\n"
+                        "Make sure %s is added to the SerializeContext and reflected to the BehaviorContext\n"
+                        "For example, verify these two exist and are being called in a Reflect function:\n"
+                        "serializeContext->Class<%s>();\n"
+                        "behaviorContext->Class<%s>();\n"
+                        "%s will not be available for scripting unless these requirements are met."
+                        , arg->m_name, method->m_name.c_str(), arg->m_name, arg->m_name, arg->m_name, method->m_name.c_str());
 
                     m_fromLua.push_back(AZStd::make_pair(fromStack, argClass));
                 }

Code/Framework/AzFramework/AzFramework/Input/Channels/InputChannelId.cpp

@@ -27,28 +27,4 @@ namespace AzFramework
             ;
         }
     }
-
-    ////////////////////////////////////////////////////////////////////////////////////////////////
-    const char* InputChannelId::GetName() const
-    {
-        return m_name.c_str();
-    }
-
-    ////////////////////////////////////////////////////////////////////////////////////////////////
-    const AZ::Crc32& InputChannelId::GetNameCrc32() const
-    {
-        return m_crc32;
-    }
-
-    ////////////////////////////////////////////////////////////////////////////////////////////////
-    bool InputChannelId::operator==(const InputChannelId& other) const
-    {
-        return (m_crc32 == other.m_crc32);
-    }
-
-    ////////////////////////////////////////////////////////////////////////////////////////////////
-    bool InputChannelId::operator!=(const InputChannelId& other) const
-    {
-        return !(*this == other);
-    }
 } // namespace AzFramework

Code/Framework/AzFramework/AzFramework/Input/Channels/InputChannelId.h

@@ -39,53 +39,58 @@ namespace AzFramework
 
         ////////////////////////////////////////////////////////////////////////////////////////////
         //! Constructor
-        //! \param[in] name Name of the input channel (will be ignored if exceeds MAX_NAME_LENGTH)
+        //! \param[in] name Name of the input channel (will be truncated if exceeds MAX_NAME_LENGTH)
         explicit constexpr InputChannelId(AZStd::string_view name = "")
-            : m_name(name)
-            , m_crc32(name)
+            : m_name(name.substr(0, MAX_NAME_LENGTH))
+            , m_crc32(name.substr(0, MAX_NAME_LENGTH))
         {
         }
 
-        constexpr InputChannelId(const InputChannelId& other) = default;
-        constexpr InputChannelId(InputChannelId&& other) = default;
-        constexpr InputChannelId& operator=(const InputChannelId& other)
-        {
-            m_name = other.m_name;
-            m_crc32 = other.m_crc32;
-            return *this;
-        }
-        constexpr InputChannelId& operator=(InputChannelId&& other)
-        {
-            m_name = AZStd::move(other.m_name);
-            m_crc32 = AZStd::move(other.m_crc32);
-            other.m_crc32 = 0;
-            return *this;
-        }
+        ////////////////////////////////////////////////////////////////////////////////////////////
+        // Default copying and moving
+        AZ_DEFAULT_COPY_MOVE(InputChannelId);
+
+        ////////////////////////////////////////////////////////////////////////////////////////////
+        //! Default destructor
         ~InputChannelId() = default;
 
         ////////////////////////////////////////////////////////////////////////////////////////////
         //! Access to the input channel's name
         //! \return Name of the input channel
-        const char* GetName() const;
+        constexpr const char* GetName() const
+        {
+            return m_name.c_str();
+        }
 
         ////////////////////////////////////////////////////////////////////////////////////////////
         //! Access to the crc32 of the input channel's name
         //! \return crc32 of the input channel name
-        const AZ::Crc32& GetNameCrc32() const;
+        constexpr const AZ::Crc32& GetNameCrc32() const
+        {
+            return m_crc32;
+        }
 
         ////////////////////////////////////////////////////////////////////////////////////////////
-        ///@{
         //! Equality comparison operator
         //! \param[in] other Another instance of the class to compare for equality
-        bool operator==(const InputChannelId& other) const;
-        bool operator!=(const InputChannelId& other) const;
-        ///@}
+        constexpr bool operator==(const InputChannelId& other) const
+        {
+            return m_crc32 == other.m_crc32;
+        }
+
+        ////////////////////////////////////////////////////////////////////////////////////////////
+        //! Inequality comparison operator
+        //! \param[in] other Another instance of the class to compare for inequality
+        constexpr bool operator!=(const InputChannelId& other) const
+        {
+            return !(*this == other);
+        }
 
     private:
         ////////////////////////////////////////////////////////////////////////////////////////////
         // Variables
         AZStd::fixed_string<MAX_NAME_LENGTH> m_name; //!< Name of the input channel
-        AZ::Crc32 m_crc32;                  //!< Crc32 of the input channel
+        AZ::Crc32 m_crc32; //!< Crc32 of the input channel name
     };
 } // namespace AzFramework
 

Code/Framework/AzFramework/AzFramework/Input/Devices/Gamepad/InputDeviceGamepad.cpp

@@ -14,14 +14,6 @@
 ////////////////////////////////////////////////////////////////////////////////////////////////////
 namespace AzFramework
 {
-    ////////////////////////////////////////////////////////////////////////////////////////////////
-    const char* InputDeviceGamepad::Name("gamepad");
-    const InputDeviceId InputDeviceGamepad::IdForIndex0(Name, 0);
-    const InputDeviceId InputDeviceGamepad::IdForIndex1(Name, 1);
-    const InputDeviceId InputDeviceGamepad::IdForIndex2(Name, 2);
-    const InputDeviceId InputDeviceGamepad::IdForIndex3(Name, 3);
-    const InputDeviceId InputDeviceGamepad::IdForIndexN(AZ::u32 n) { return InputDeviceId(Name, n); }
-
     ////////////////////////////////////////////////////////////////////////////////////////////////
     bool InputDeviceGamepad::IsGamepadDevice(const InputDeviceId& inputDeviceId)
     {

Code/Framework/AzFramework/AzFramework/Input/Devices/Gamepad/InputDeviceGamepad.h

@@ -32,16 +32,16 @@ namespace AzFramework
     public:
         ////////////////////////////////////////////////////////////////////////////////////////////
         //! The name used to identify any game-pad input device
-        static const char* Name;
+        static constexpr inline const char* Name{"gamepad"};
 
         ////////////////////////////////////////////////////////////////////////////////////////////
         //! The id used to identify a game-pad input device with a specific index
         ///@{
-        static const InputDeviceId IdForIndex0;
-        static const InputDeviceId IdForIndex1;
-        static const InputDeviceId IdForIndex2;
-        static const InputDeviceId IdForIndex3;
-        static const InputDeviceId IdForIndexN(AZ::u32 n);
+        static constexpr inline InputDeviceId IdForIndex0{Name, 0};
+        static constexpr inline InputDeviceId IdForIndex1{Name, 1};
+        static constexpr inline InputDeviceId IdForIndex2{Name, 2};
+        static constexpr inline InputDeviceId IdForIndex3{Name, 3};
+        static constexpr inline InputDeviceId IdForIndexN(AZ::u32 n) { return InputDeviceId(Name, n); }
         ///@}
 
         ////////////////////////////////////////////////////////////////////////////////////////////

Code/Framework/AzFramework/AzFramework/Input/Devices/InputDeviceId.cpp

@@ -29,71 +29,4 @@ namespace AzFramework
             ;
         }
     }
-
-    ////////////////////////////////////////////////////////////////////////////////////////////////
-    InputDeviceId::InputDeviceId(const char* name, AZ::u32 index)
-        : m_crc32(name)
-        , m_index(index)
-    {
-        memset(m_name, 0, AZ_ARRAY_SIZE(m_name));
-        azstrncpy(m_name, NAME_BUFFER_SIZE, name, MAX_NAME_LENGTH);
-    }
-
-    ////////////////////////////////////////////////////////////////////////////////////////////////
-    InputDeviceId::InputDeviceId(const InputDeviceId& other)
-        : m_crc32(other.m_crc32)
-        , m_index(other.m_index)
-    {
-        memset(m_name, 0, AZ_ARRAY_SIZE(m_name));
-        azstrcpy(m_name, NAME_BUFFER_SIZE, other.m_name);
-    }
-
-    ////////////////////////////////////////////////////////////////////////////////////////////////
-    InputDeviceId& InputDeviceId::operator=(const InputDeviceId& other)
-    {
-        azstrcpy(m_name, NAME_BUFFER_SIZE, other.m_name);
-        m_crc32 = other.m_crc32;
-        m_index = other.m_index;
-        return *this;
-    }
-
-    ////////////////////////////////////////////////////////////////////////////////////////////////
-    const char* InputDeviceId::GetName() const
-    {
-        return m_name;
-    }
-
-    ////////////////////////////////////////////////////////////////////////////////////////////////
-    const AZ::Crc32& InputDeviceId::GetNameCrc32() const
-    {
-        return m_crc32;
-    }
-
-    ////////////////////////////////////////////////////////////////////////////////////////////////
-    AZ::u32 InputDeviceId::GetIndex() const
-    {
-        return m_index;
-    }
-
-    ////////////////////////////////////////////////////////////////////////////////////////////////
-    bool InputDeviceId::operator==(const InputDeviceId& other) const
-    {
-        return (m_crc32 == other.m_crc32) && (m_index == other.m_index);
-    }
-
-    ////////////////////////////////////////////////////////////////////////////////////////////////
-    bool InputDeviceId::operator!=(const InputDeviceId& other) const
-    {
-        return !(*this == other);
-    }
-
-    ////////////////////////////////////////////////////////////////////////////////////////////////
-    bool InputDeviceId::operator<(const InputDeviceId& other) const
-    {
-        if (m_index == other.m_index)
-        {
-            return m_crc32 < other.m_crc32;
-        }
-        return m_index < other.m_index;
-    }
 } // namespace AzFramework

Code/Framework/AzFramework/AzFramework/Input/Devices/InputDeviceId.h

@@ -11,6 +11,7 @@
 #include <AzCore/Math/Crc.h>
 #include <AzCore/RTTI/ReflectContext.h>
 #include <AzCore/std/hash.h>
+#include <AzCore/std/string/fixed_string.h>
 
 ////////////////////////////////////////////////////////////////////////////////////////////////////
 namespace AzFramework
@@ -22,8 +23,7 @@ namespace AzFramework
     public:
         ////////////////////////////////////////////////////////////////////////////////////////////
         // Constants
-        static const int NAME_BUFFER_SIZE = 64;
-        static const int MAX_NAME_LENGTH = NAME_BUFFER_SIZE - 1;
+        static constexpr int MAX_NAME_LENGTH = 64;
 
         ////////////////////////////////////////////////////////////////////////////////////////////
         // Allocator
@@ -41,17 +41,16 @@ namespace AzFramework
         //! Constructor
         //! \param[in] name Name of the input device (will be truncated if exceeds MAX_NAME_LENGTH)
         //! \param[in] index Index of the input device (optional)
-        explicit InputDeviceId(const char* name, AZ::u32 index = 0);
+        explicit constexpr InputDeviceId(AZStd::string_view name, AZ::u32 index = 0)
+            : m_name(name.substr(0, MAX_NAME_LENGTH))
+            , m_crc32(name.substr(0, MAX_NAME_LENGTH))
+            , m_index(index)
+        {
+        }
 
         ////////////////////////////////////////////////////////////////////////////////////////////
-        //! Copy constructor
-        //! \param[in] other Another instance of the class to copy from
-        InputDeviceId(const InputDeviceId& other);
-
-        ////////////////////////////////////////////////////////////////////////////////////////////
-        //! Copy assignment operator
-        //! \param[in] other Another instance of the class to copy from
-        InputDeviceId& operator=(const InputDeviceId& other);
+        // Default copying and moving
+        AZ_DEFAULT_COPY_MOVE(InputDeviceId);
 
         ////////////////////////////////////////////////////////////////////////////////////////////
         //! Default destructor
@@ -60,12 +59,18 @@ namespace AzFramework
         ////////////////////////////////////////////////////////////////////////////////////////////
         //! Access to the input device's name
         //! \return Name of the input device
-        const char* GetName() const;
+        constexpr const char* GetName() const
+        {
+            return m_name.c_str();
+        }
 
         ////////////////////////////////////////////////////////////////////////////////////////////
         //! Access to the crc32 of the input device's name
         //! \return crc32 of the input device name
-        const AZ::Crc32& GetNameCrc32() const;
+        constexpr const AZ::Crc32& GetNameCrc32() const
+        {
+            return m_crc32;
+        }
 
         ////////////////////////////////////////////////////////////////////////////////////////////
         //! Access to the input device's index. Used for differentiating between multiple instances
@@ -75,27 +80,45 @@ namespace AzFramework
         //! at startup using indicies 0->3. As gamepads connect/disconnect at runtime we assign the
         //! appropriate (system dependent) local user id (see InputDevice::GetAssignedLocalUserId).
         //! \return Index of the input device
-        AZ::u32 GetIndex() const;
+        constexpr AZ::u32 GetIndex() const
+        {
+            return m_index;
+        }
 
         ////////////////////////////////////////////////////////////////////////////////////////////
-        ///@{
         //! Equality comparison operator
         //! \param[in] other Another instance of the class to compare for equality
-        bool operator==(const InputDeviceId& other) const;
-        bool operator!=(const InputDeviceId& other) const;
-        ///@}
+        constexpr bool operator==(const InputDeviceId& other) const
+        {
+            return (m_crc32 == other.m_crc32) && (m_index == other.m_index);
+        }
+
+        ////////////////////////////////////////////////////////////////////////////////////////////
+        //! Inequality comparison operator
+        //! \param[in] other Another instance of the class to compare for inequality
+        constexpr bool operator!=(const InputDeviceId& other) const
+        {
+            return !(*this == other);
+        }
 
         ////////////////////////////////////////////////////////////////////////////////////////////
         //! Less than comparison operator
         //! \param[in] other Another instance of the class to compare
-        bool operator<(const InputDeviceId& other) const;
+        constexpr bool operator<(const InputDeviceId& other) const
+        {
+            if (m_index == other.m_index)
+            {
+                return m_crc32 < other.m_crc32;
+            }
+            return m_index < other.m_index;
+        }
 
     private:
         ////////////////////////////////////////////////////////////////////////////////////////////
         // Variables
-        char      m_name[NAME_BUFFER_SIZE]; //!< Name of the input device
-        AZ::Crc32 m_crc32;                  //!< Crc32 of the input device
-        AZ::u32   m_index;                  //!< Index of the input device
+        AZStd::fixed_string<MAX_NAME_LENGTH> m_name; //!< Name of the input device
+        AZ::Crc32 m_crc32; //!< Crc32 of the input device name
+        AZ::u32 m_index; //!< Index of the input device
     };
 } // namespace AzFramework
 

Code/Framework/AzFramework/AzFramework/Input/Devices/Keyboard/InputDeviceKeyboard.cpp

@@ -15,9 +15,6 @@
 ////////////////////////////////////////////////////////////////////////////////////////////////////
 namespace AzFramework
 {
-    ////////////////////////////////////////////////////////////////////////////////////////////////
-    const InputDeviceId InputDeviceKeyboard::Id("keyboard");
-
     ////////////////////////////////////////////////////////////////////////////////////////////////
     bool InputDeviceKeyboard::IsKeyboardDevice(const InputDeviceId& inputDeviceId)
     {

Code/Framework/AzFramework/AzFramework/Input/Devices/Keyboard/InputDeviceKeyboard.h

@@ -33,7 +33,7 @@ namespace AzFramework
     public:
         ////////////////////////////////////////////////////////////////////////////////////////////
         //! The id used to identify the primary physical keyboard input device
-        static const InputDeviceId Id;
+        static constexpr inline InputDeviceId Id{"keyboard"};
 
         ////////////////////////////////////////////////////////////////////////////////////////////
         //! Check whether an input device id identifies a physical keyboard (regardless of index)

Code/Framework/AzFramework/AzFramework/Input/Devices/Motion/InputDeviceMotion.cpp

@@ -14,9 +14,6 @@
 ////////////////////////////////////////////////////////////////////////////////////////////////////
 namespace AzFramework
 {
-    ////////////////////////////////////////////////////////////////////////////////////////////////
-    const InputDeviceId InputDeviceMotion::Id("motion");
-
     ////////////////////////////////////////////////////////////////////////////////////////////////
     bool InputDeviceMotion::IsMotionDevice(const InputDeviceId& inputDeviceId)
     {

Code/Framework/AzFramework/AzFramework/Input/Devices/Motion/InputDeviceMotion.h

@@ -28,7 +28,7 @@ namespace AzFramework
     public:
         ////////////////////////////////////////////////////////////////////////////////////////////
         //! The id used to identify the primary motion input device
-        static const InputDeviceId Id;
+        static constexpr inline InputDeviceId Id{"motion"};
 
         ////////////////////////////////////////////////////////////////////////////////////////////
         //! Check whether an input device id identifies a motion device (regardless of index)

Code/Framework/AzFramework/AzFramework/Input/Devices/Mouse/InputDeviceMouse.cpp

@@ -15,18 +15,6 @@
 ////////////////////////////////////////////////////////////////////////////////////////////////////
 namespace AzFramework
 {
-    ////////////////////////////////////////////////////////////////////////////////////////////////
-    const AZ::u32 InputDeviceMouse::MovementSampleRateDefault = 60;
-
-    ////////////////////////////////////////////////////////////////////////////////////////////////
-    const AZ::u32 InputDeviceMouse::MovementSampleRateQueueAll = std::numeric_limits<AZ::u32>::max();
-
-    ////////////////////////////////////////////////////////////////////////////////////////////////
-    const AZ::u32 InputDeviceMouse::MovementSampleRateAccumulateAll = 0;
-
-    ////////////////////////////////////////////////////////////////////////////////////////////////
-    const InputDeviceId InputDeviceMouse::Id("mouse");
-
     ////////////////////////////////////////////////////////////////////////////////////////////////
     bool InputDeviceMouse::IsMouseDevice(const InputDeviceId& inputDeviceId)
     {

Code/Framework/AzFramework/AzFramework/Input/Devices/Mouse/InputDeviceMouse.h

@@ -31,23 +31,23 @@ namespace AzFramework
         ////////////////////////////////////////////////////////////////////////////////////////////
         //! Default sample rate for raw mouse movement events that aims to strike a balance between
         //! responsiveness and performance.
-        static const AZ::u32 MovementSampleRateDefault;
+        static constexpr inline AZ::u32 MovementSampleRateDefault{60};
 
         ////////////////////////////////////////////////////////////////////////////////////////////
         //! Sample rate for raw mouse movement that will cause all events received in the same frame
         //! to be queued and dispatched as individual events. This results in maximum responsiveness
         //! but may potentially impact performance depending how many events happen over each frame.
-        static const AZ::u32 MovementSampleRateQueueAll;
+        static constexpr inline AZ::u32 MovementSampleRateQueueAll{std::numeric_limits<AZ::u32>::max()};
 
         ////////////////////////////////////////////////////////////////////////////////////////////
         //! Sample rate for raw mouse movement that will cause all events received in the same frame
         //! to be accumulated and dispatched as a single event. Optimal for performance, but results
         //! in sluggish/unresponsive mouse movement, especially when running at low frame rates.
-        static const AZ::u32 MovementSampleRateAccumulateAll;
+        static constexpr inline AZ::u32 MovementSampleRateAccumulateAll{0};
 
         ////////////////////////////////////////////////////////////////////////////////////////////
         //! The id used to identify the primary mouse input device
-        static const InputDeviceId Id;
+        static constexpr inline InputDeviceId Id{"mouse"};
 
         ////////////////////////////////////////////////////////////////////////////////////////////
         //! Check whether an input device id identifies a mouse (regardless of index)

Code/Framework/AzFramework/AzFramework/Input/Devices/Touch/InputDeviceTouch.cpp

@@ -15,9 +15,6 @@
 ////////////////////////////////////////////////////////////////////////////////////////////////////
 namespace AzFramework
 {
-    ////////////////////////////////////////////////////////////////////////////////////////////////
-    const InputDeviceId InputDeviceTouch::Id("touch");
-
     ////////////////////////////////////////////////////////////////////////////////////////////////
     bool InputDeviceTouch::IsTouchDevice(const InputDeviceId& inputDeviceId)
     {

Code/Framework/AzFramework/AzFramework/Input/Devices/Touch/InputDeviceTouch.h

@@ -25,7 +25,7 @@ namespace AzFramework
     public:
         ////////////////////////////////////////////////////////////////////////////////////////////
         //! The id used to identify the primary touch input device
-        static const InputDeviceId Id;
+        static constexpr inline InputDeviceId Id{"touch"};
 
         ////////////////////////////////////////////////////////////////////////////////////////////
         //! Check whether an input device id identifies a touch device (regardless of index)

Code/Framework/AzFramework/AzFramework/Input/Devices/VirtualKeyboard/InputDeviceVirtualKeyboard.cpp

@@ -14,9 +14,6 @@
 ////////////////////////////////////////////////////////////////////////////////////////////////////
 namespace AzFramework
 {
-    ////////////////////////////////////////////////////////////////////////////////////////////////
-    const InputDeviceId InputDeviceVirtualKeyboard::Id("virtual_keyboard");
-
     ////////////////////////////////////////////////////////////////////////////////////////////////
     bool InputDeviceVirtualKeyboard::IsVirtualKeyboardDevice(const InputDeviceId& inputDeviceId)
     {

Code/Framework/AzFramework/AzFramework/Input/Devices/VirtualKeyboard/InputDeviceVirtualKeyboard.h

@@ -25,7 +25,7 @@ namespace AzFramework
     public:
         ////////////////////////////////////////////////////////////////////////////////////////////
         //! The id used to identify the primary virtual keyboard input device
-        static const InputDeviceId Id;
+        static constexpr inline InputDeviceId Id{"virtual_keyboard"};
 
         ////////////////////////////////////////////////////////////////////////////////////////////
         //! Check whether an input device id identifies a virtual keyboard (regardless of index)

Code/Framework/AzFramework/AzFramework/Spawnable/RootSpawnableInterface.h

@@ -30,12 +30,22 @@ namespace AzFramework
         
         //! Called when the root spawnable has been assigned a new value. This may be called several times without a call to release
         //!     in between.
+        //! @note: The callback is not queued but immediately called from a random thread. This is done because this callback is typically
+        //!     used before entities are spawned and if it's queued then the entities spawn before this callback is called.
         //! @param rootSpawnable The new root spawnable that was assigned.
         //! @param generation The generation of the root spawnable. This will increment every time a new spawnable is assigned.
         virtual void OnRootSpawnableAssigned([[maybe_unused]] AZ::Data::Asset<Spawnable> rootSpawnable,
             [[maybe_unused]] uint32_t generation) {}
+        //! Called when the root spawnable has completed spawning of entities. This may be called several times without a call to release
+        //!     in between.
+        //! @note: This callback is queued and will be called with a delay and from the main thread.
+        //! @param rootSpawnable The new root spawnable that was used to spawn entities from.
+        //! @param generation The generation of the root spawnable. This will increment every time a new spawnable is assigned.
+        virtual void OnRootSpawnableReady(
+            [[maybe_unused]] AZ::Data::Asset<Spawnable> rootSpawnable, [[maybe_unused]] uint32_t generation) {}
         //! Called when the root spawnable has Released. This will only be called if there's no root spawnable assigned to take the
         //!     place of the original root spawnable.
+        //! Note: This callback is queued and will be called with a delay and from the main thread.
         //! @param generation The generation of the root spawnable that was released.
         virtual void OnRootSpawnableReleased([[maybe_unused]] uint32_t generation) {}
     };

Code/Framework/AzFramework/AzFramework/Spawnable/Spawnable.cpp

@@ -6,12 +6,473 @@
  *
  */
 
+#include <AzCore/Asset/AssetSerializer.h>
 #include <AzCore/RTTI/ReflectContext.h>
 #include <AzCore/Serialization/SerializeContext.h>
+#include <AzCore/std/numeric.h>
+#include <AzCore/std/sort.h>
+#include <AzCore/std/typetraits/typetraits.h>
 #include <AzFramework/Spawnable/Spawnable.h>
 
 namespace AzFramework
 {
+    //
+    // EntityAlias
+    //
+
+    bool Spawnable::EntityAlias::HasLowerIndex(const EntityAlias& other) const
+    {
+        return m_sourceIndex == other.m_sourceIndex ?
+            m_aliasType < other.m_aliasType :
+            m_sourceIndex < other.m_sourceIndex;
+    }
+
+
+    //
+    // EntityAliasVisitorBase
+    //
+
+    bool Spawnable::EntityAliasVisitorBase::IsValid(const EntityAliasList* aliases) const
+    {
+        return aliases != nullptr;
+    }
+
+    bool Spawnable::EntityAliasVisitorBase::HasAliases(const EntityAliasList* aliases) const
+    {
+        AZ_Assert(aliases, "Attempting to visit entity aliases on a spawnable that wasn't locked.");
+        return !aliases->empty();
+    }
+
+    bool Spawnable::EntityAliasVisitorBase::AreAllSpawnablesReady(const EntityAliasList* aliases) const
+    {
+        AZ_Assert(aliases, "Attempting to visit entity aliases on a spawnable that wasn't locked.");
+        for (const EntityAlias& alias : *aliases)
+        {
+            if (!alias.m_queueLoad ||
+                alias.m_aliasType == Spawnable::EntityAliasType::Original ||
+                alias.m_aliasType == Spawnable::EntityAliasType::Disable)
+            {
+                continue;
+            }
+            if (!alias.m_spawnable.IsReady() && !alias.m_spawnable.IsError())
+            {
+                return false;
+            }
+        }
+        return true;
+    }
+
+    auto Spawnable::EntityAliasVisitorBase::begin(const EntityAliasList* aliases) const -> EntityAliasList::const_iterator
+    {
+        AZ_Assert(aliases, "Attempting to visit entity aliases on a spawnable that wasn't locked.");
+        return aliases->cbegin();
+    }
+
+    auto Spawnable::EntityAliasVisitorBase::end(const EntityAliasList* aliases) const -> EntityAliasList::const_iterator
+    {
+        AZ_Assert(aliases, "Attempting to visit entity aliases on a spawnable that wasn't locked.");
+        return aliases->cend();
+    }
+
+    auto Spawnable::EntityAliasVisitorBase::cbegin(const EntityAliasList* aliases) const -> EntityAliasList::const_iterator
+    {
+        AZ_Assert(aliases, "Attempting to visit entity aliases on a spawnable that wasn't locked.");
+        return aliases->cbegin();
+    }
+
+    auto Spawnable::EntityAliasVisitorBase::cend(const EntityAliasList* aliases) const -> EntityAliasList::const_iterator
+    {
+        AZ_Assert(aliases, "Attempting to visit entity aliases on a spawnable that wasn't locked.");
+        return aliases->cend();
+    }
+
+    void Spawnable::EntityAliasVisitorBase::ListTargetSpawnables(
+        const EntityAliasList* aliases, const ListTargetSpawanblesCallback& callback) const
+    {
+        AZ_Assert(aliases, "Attempting to visit entity aliases on a spawnable that wasn't locked.");
+        AZStd::unordered_set<AZ::Data::AssetId> spawnableIds;
+        for (const Spawnable::EntityAlias& alias : *aliases)
+        {
+            // If the spawnable id is not valid it means that the alias is referencing the spawnable it's stored on.
+            if (alias.m_spawnable.GetId().IsValid())
+            {
+                auto it = spawnableIds.find(alias.m_spawnable.GetId());
+                if (it == spawnableIds.end())
+                {
+                    callback(alias.m_spawnable);
+                    spawnableIds.emplace(alias.m_spawnable.GetId());
+                }
+            }
+        }
+    }
+
+    void Spawnable::EntityAliasVisitorBase::ListTargetSpawnables(
+        const EntityAliasList* aliases, AZ::Crc32 tag, const ListTargetSpawanblesCallback& callback) const
+    {
+        AZ_Assert(aliases, "Attempting to visit entity aliases on a spawnable that wasn't locked.");
+        AZStd::unordered_set<AZ::Data::AssetId> spawnableIds;
+        for (const Spawnable::EntityAlias& alias : *aliases)
+        {
+            // If the spawnable id is not valid it means that the alias is referencing the spawnable it's stored on.
+            if (alias.m_tag == tag && alias.m_spawnable.GetId().IsValid())
+            {
+                auto it = spawnableIds.find(alias.m_spawnable.GetId());
+                if (it == spawnableIds.end())
+                {
+                    callback(alias.m_spawnable);
+                    spawnableIds.emplace(alias.m_spawnable.GetId());
+                }
+            }
+        }
+    }
+
+
+    //
+    // EntityAliasVisitor
+    //
+
+    Spawnable::EntityAliasVisitor::EntityAliasVisitor(Spawnable& owner, EntityAliasList* entityAliasList)
+        : m_owner(owner)
+        , m_entityAliasList(entityAliasList)
+    {
+    }
+
+    Spawnable::EntityAliasVisitor::~EntityAliasVisitor()
+    {
+        if (IsValid())
+        {
+            Optimize();
+
+            AZ_Assert(
+                m_owner.m_shareState == ShareState::ReadWrite, "Attempting to unlock a spawnable that's not in the locked state (%i).",
+                m_owner.m_shareState.load());
+            m_owner.m_shareState = ShareState::NotShared;
+        }
+    }
+
+    Spawnable::EntityAliasVisitor::EntityAliasVisitor(EntityAliasVisitor&& rhs)
+        : m_owner(rhs.m_owner)
+        , m_entityAliasList(rhs.m_entityAliasList)
+    {
+        m_dirty = rhs.m_dirty;
+
+        rhs.m_entityAliasList = nullptr;
+        rhs.m_dirty = false;
+    }
+
+    auto Spawnable::EntityAliasVisitor::operator=(EntityAliasVisitor&& rhs) -> EntityAliasVisitor&
+    {
+        if (this != &rhs)
+        {
+            this->~EntityAliasVisitor();
+            new(this) EntityAliasVisitor(AZStd::move(rhs));
+        }
+        return *this;
+    }
+
+    bool Spawnable::EntityAliasVisitor::IsValid() const
+    {
+        return EntityAliasVisitorBase::IsValid(m_entityAliasList);
+    }
+
+    bool Spawnable::EntityAliasVisitor::HasAliases() const
+    {
+        return EntityAliasVisitorBase::HasAliases(m_entityAliasList);
+    }
+
+    bool Spawnable::EntityAliasVisitor::AreAllSpawnablesReady() const
+    {
+        return EntityAliasVisitorBase::AreAllSpawnablesReady(m_entityAliasList);
+    }
+
+    auto Spawnable::EntityAliasVisitor::begin() const -> EntityAliasList::const_iterator
+    {
+        return EntityAliasVisitorBase::begin(m_entityAliasList);
+    }
+
+    auto Spawnable::EntityAliasVisitor::end() const -> EntityAliasList::const_iterator
+    {
+        return EntityAliasVisitorBase::end(m_entityAliasList);
+    }
+
+    auto Spawnable::EntityAliasVisitor::cbegin() const -> EntityAliasList::const_iterator
+    {
+        return EntityAliasVisitorBase::cbegin(m_entityAliasList);
+    }
+
+    auto Spawnable::EntityAliasVisitor::cend() const -> EntityAliasList::const_iterator
+    {
+        return EntityAliasVisitorBase::cend(m_entityAliasList);
+    }
+
+    void Spawnable::EntityAliasVisitor::ListTargetSpawnables(const ListTargetSpawanblesCallback& callback) const
+    {
+        EntityAliasVisitorBase::ListTargetSpawnables(m_entityAliasList, callback);
+    }
+
+    void Spawnable::EntityAliasVisitor::ListTargetSpawnables(AZ::Crc32 tag, const ListTargetSpawanblesCallback& callback) const
+    {
+        EntityAliasVisitorBase::ListTargetSpawnables(m_entityAliasList, tag, callback);
+    }
+
+    void Spawnable::EntityAliasVisitor::AddAlias(
+        AZ::Data::Asset<Spawnable> targetSpawnable,
+        AZ::Crc32 tag,
+        uint32_t sourceIndex,
+        uint32_t targetIndex,
+        Spawnable::EntityAliasType aliasType,
+        bool queueLoad)
+    {
+        AZ_Assert(m_entityAliasList, "Attempting to visit entity aliases on a spawnable that wasn't locked.");
+        AZ_Assert(sourceIndex < m_owner.GetEntities().size(), "Invalid source index (%i) for entity alias", sourceIndex);
+        if (targetSpawnable.IsReady())
+        {
+            AZ_Assert(
+                targetIndex < targetSpawnable->GetEntities().size(), "Invalid target index (%i) for entity alias '%s'", targetIndex,
+                targetSpawnable.GetHint().c_str());
+        }
+
+        m_entityAliasList->push_back(Spawnable::EntityAlias{ targetSpawnable, tag, sourceIndex, targetIndex, aliasType, queueLoad });
+        m_dirty = true;
+    }
+
+    void Spawnable::EntityAliasVisitor::ListSpawnablesRequiringLoad(const ListSpawnablesRequiringLoadCallback& callback)
+    {
+        AZ_Assert(m_entityAliasList, "Attempting to visit entity aliases on a spawnable that wasn't locked.");
+        for (Spawnable::EntityAlias& alias : *m_entityAliasList)
+        {
+            if (alias.m_queueLoad &&
+                alias.m_aliasType != Spawnable::EntityAliasType::Original &&
+                alias.m_aliasType != Spawnable::EntityAliasType::Disable &&
+                !alias.m_spawnable.IsLoading() &&
+                !alias.m_spawnable.IsReady() &&
+                !alias.m_spawnable.IsError())
+            {
+                callback(alias.m_spawnable);
+            }
+        }
+    }
+
+    void Spawnable::EntityAliasVisitor::UpdateAliases(const UpdateCallback& callback)
+    {
+        AZ_Assert(m_entityAliasList, "Attempting to visit entity aliases on a spawnable that wasn't locked.");
+        for (Spawnable::EntityAlias& alias : *m_entityAliasList)
+        {
+            AZ::Data::Asset<Spawnable> targetSpawnable(alias.m_spawnable);
+            callback(alias.m_aliasType, alias.m_queueLoad, targetSpawnable, alias.m_tag, alias.m_sourceIndex, alias.m_targetIndex);
+        }
+        m_dirty = true;
+    }
+
+    void Spawnable::EntityAliasVisitor::UpdateAliases(AZ::Crc32 tag, const UpdateCallback& callback)
+    {
+        AZ_Assert(m_entityAliasList, "Attempting to visit entity aliases on a spawnable that wasn't locked.");
+        for (Spawnable::EntityAlias& alias : *m_entityAliasList)
+        {
+            if (alias.m_tag == tag)
+            {
+                AZ::Data::Asset<Spawnable> targetSpawnable(alias.m_spawnable);
+                callback(alias.m_aliasType, alias.m_queueLoad, targetSpawnable, alias.m_tag, alias.m_sourceIndex, alias.m_targetIndex);
+                m_dirty = true;
+            }
+        }
+    }
+
+    void Spawnable::EntityAliasVisitor::UpdateAliasType(uint32_t index, Spawnable::EntityAliasType newType)
+    {
+        AZ_Assert(m_entityAliasList, "Attempting to visit entity aliases on a spawnable that wasn't locked.");
+        AZ_Assert(
+            index < m_entityAliasList->size(), "Unable to update entity alias at index %i as there are only %zu aliases in spawnable.",
+            index, m_entityAliasList->size());
+        (*m_entityAliasList)[index].m_aliasType = newType;
+        m_dirty = true;
+    }
+
+    void Spawnable::EntityAliasVisitor::Optimize()
+    {
+        AZ_Assert(m_entityAliasList, "Attempting to visit entity aliases on a spawnable that wasn't locked.");
+        if (m_dirty)
+        {
+            AZStd::stable_sort(
+                m_entityAliasList->begin(), m_entityAliasList->end(),
+                [](const Spawnable::EntityAlias& lhs, const Spawnable::EntityAlias& rhs)
+                {
+                    // Sort by source index from smallest to largest so during spawning the entities can be iterated linearly over.
+                    // If the source index is the same then sort by alias type so the next steps can optimize away superfluous steps.
+                    return lhs.HasLowerIndex(rhs);
+                });
+
+            // Remove aliases that are not going to have any practical effect and insert aliases where needed to simplify the spawning.
+            // This is done at runtime rather than at build time because the above ebus allows other systems to make adjustments to the
+            // aliases, for instance Networking can decide to disable certain aliases when running on a client. This in turn also requires
+            // the aliases to be in their recorded order during building as the ebus handlers may depend on that order to determine what
+            // entities need to be updated.
+            uint32_t previousIndex = AZStd::numeric_limits<uint32_t>::max();
+            Spawnable::EntityAliasType previousType =
+                static_cast<Spawnable::EntityAliasType>(AZStd::numeric_limits<AZStd::underlying_type_t<Spawnable::EntityAliasType>>::max());
+            Spawnable::EntityAlias* it = m_entityAliasList->begin();
+            Spawnable::EntityAlias* end = m_entityAliasList->end();
+            while (it < end)
+            {
+                // If there's a switch to a new source index and the previous index only had an original it can
+                // be removed.
+                if (previousType == Spawnable::EntityAliasType::Original && previousIndex != it->m_sourceIndex)
+                {
+                    it = m_entityAliasList->erase(it - 1);
+                    end = m_entityAliasList->end();
+                    if (it == end)
+                    {
+                        break;
+                    }
+                }
+
+                switch (it->m_aliasType)
+                {
+                case Spawnable::EntityAliasType::Original:
+                    [[fallthrough]];
+                case Spawnable::EntityAliasType::Disable:
+                    [[fallthrough]];
+                case Spawnable::EntityAliasType::Replace:
+                    // If the previous entry was a disabled, original or replace alias then remove it as it will be overwritten by the
+                    // current entry.
+                    if (previousIndex == it->m_sourceIndex &&
+                        (previousType == Spawnable::EntityAliasType::Original ||
+                         previousType == Spawnable::EntityAliasType::Disable ||
+                         previousType == Spawnable::EntityAliasType::Replace))
+                    {
+                        previousIndex = it->m_sourceIndex;
+                        previousType = it->m_aliasType;
+                        // Erase instead of a swap-and-pop in order to preserver the order.
+                        it = m_entityAliasList->erase(it - 1) + 1;
+                        end = m_entityAliasList->end();
+                    }
+                    else
+                    {
+                        previousIndex = it->m_sourceIndex;
+                        previousType = it->m_aliasType;
+                        ++it;
+                    }
+                    break;
+                case Spawnable::EntityAliasType::Additional:
+                    [[fallthrough]];
+                case Spawnable::EntityAliasType::Merge:
+                    // If this is the first entry for this index then insert an original in front of it so the spawnable entity manager
+                    // doesn't have to check for the case there's a merge and/or addition without an entity to extend.
+                    if (previousIndex != it->m_sourceIndex)
+                    {
+                        Spawnable::EntityAlias insert;
+                        // No load, as the asset is already loaded.
+                        insert.m_spawnable = AZ::Data::Asset<Spawnable>({}, azrtti_typeid<Spawnable>());
+                        insert.m_sourceIndex = it->m_sourceIndex;
+                        insert.m_targetIndex = it->m_sourceIndex; // Source index as the original entry for this slot is added.
+                        insert.m_aliasType = Spawnable::EntityAliasType::Original;
+
+                        previousIndex = it->m_sourceIndex;
+                        previousType = it->m_aliasType;
+
+                        // Insert to maintain the order.
+                        it = m_entityAliasList->insert(it, AZStd::move(insert));
+                        it += 2;
+                        end = m_entityAliasList->end();
+                    }
+                    else
+                    {
+                        previousType = it->m_aliasType;
+                        ++it;
+                    }
+                    break;
+                default:
+                    AZ_Assert(false, "Invalid Spawnable entity alias type found during asset loading: %i", it->m_aliasType);
+                    break;
+                }
+            }
+
+            // Check if the last entry is an "Original" in which case it can be removed.
+            if (!m_entityAliasList->empty() && m_entityAliasList->back().m_aliasType == Spawnable::EntityAliasType::Original)
+            {
+                m_entityAliasList->pop_back();
+            }
+
+            // Reclaim memory because after this point the aliases will not change anymore.
+            m_entityAliasList->shrink_to_fit();
+            m_dirty = false;
+        }
+    }
+
+
+
+    //
+    // EntityAliasConstVisitor
+    //
+
+    Spawnable::EntityAliasConstVisitor::EntityAliasConstVisitor(const Spawnable& owner, const EntityAliasList* entityAliasList)
+        : m_owner(owner)
+        , m_entityAliasList(entityAliasList)
+    {
+    }
+
+    Spawnable::EntityAliasConstVisitor::~EntityAliasConstVisitor()
+    {
+        if (IsValid())
+        {
+            AZ_Assert(
+                m_owner.m_shareState <= ShareState::Read, "Attempting to unlock a read shared spawnable that was not in a read shared mode (%i).",
+                m_owner.m_shareState.load());
+            m_owner.m_shareState++;
+        }
+    }
+
+    bool Spawnable::EntityAliasConstVisitor::IsValid() const
+    {
+        return EntityAliasVisitorBase::IsValid(m_entityAliasList);
+    }
+
+    bool Spawnable::EntityAliasConstVisitor::HasAliases() const
+    {
+        return EntityAliasVisitorBase::HasAliases(m_entityAliasList);
+    }
+
+    bool Spawnable::EntityAliasConstVisitor::AreAllSpawnablesReady() const
+    {
+        return EntityAliasVisitorBase::AreAllSpawnablesReady(m_entityAliasList);
+    }
+
+    auto Spawnable::EntityAliasConstVisitor::begin() const -> EntityAliasList::const_iterator
+    {
+        return EntityAliasVisitorBase::begin(m_entityAliasList);
+    }
+
+    auto Spawnable::EntityAliasConstVisitor::end() const -> EntityAliasList::const_iterator
+    {
+        return EntityAliasVisitorBase::end(m_entityAliasList);
+    }
+
+    auto Spawnable::EntityAliasConstVisitor::cbegin() const -> EntityAliasList::const_iterator
+    {
+        return EntityAliasVisitorBase::cbegin(m_entityAliasList);
+    }
+
+    auto Spawnable::EntityAliasConstVisitor::cend() const -> EntityAliasList::const_iterator
+    {
+        return EntityAliasVisitorBase::cend(m_entityAliasList);
+    }
+
+    void Spawnable::EntityAliasConstVisitor::ListTargetSpawnables(const ListTargetSpawanblesCallback& callback) const
+    {
+        EntityAliasVisitorBase::ListTargetSpawnables(m_entityAliasList, callback);
+    }
+
+    void Spawnable::EntityAliasConstVisitor::ListTargetSpawnables(AZ::Crc32 tag, const ListTargetSpawanblesCallback& callback) const
+    {
+        EntityAliasVisitorBase::ListTargetSpawnables(m_entityAliasList, tag, callback);
+    }
+
+
+
+    //
+    // Spawnable
+    //
+
     Spawnable::Spawnable(const AZ::Data::AssetId& id, AssetStatus status)
         : AZ::Data::AssetData(id, status)
     {
@@ -27,6 +488,33 @@ namespace AzFramework
         return m_entities;
     }
 
+    auto Spawnable::TryGetAliasesConst() const -> EntityAliasConstVisitor
+    {
+        int32_t expected = ShareState::NotShared;
+        do
+        {
+            // Try to set the lock to a negative number to indicate a shared read.
+            if (m_shareState.compare_exchange_strong(expected, expected - 1))
+            {
+                return EntityAliasConstVisitor(*this, &m_entityAliases);
+            }
+        // as long as the value is negative or not shared then keep trying to get a shared read lock.
+        } while (expected <= 0);
+        return EntityAliasConstVisitor(*this, nullptr);
+    }
+
+    auto Spawnable::TryGetAliases() const -> EntityAliasConstVisitor
+    {
+        return TryGetAliasesConst();
+    }
+
+    auto Spawnable::TryGetAliases() -> EntityAliasVisitor
+    {
+        int32_t expected = ShareState::NotShared;
+        return m_shareState.compare_exchange_strong(expected, ShareState::ReadWrite) ? EntityAliasVisitor(*this, &m_entityAliases)
+                                                                                     : EntityAliasVisitor(*this, nullptr);
+    }
+
     bool Spawnable::IsEmpty() const
     {
         return m_entities.empty();
@@ -44,11 +532,29 @@ namespace AzFramework
 
     void Spawnable::Reflect(AZ::ReflectContext* context)
     {
+        EntityAlias::Reflect(context);
+
         if (auto* serializeContext = azrtti_cast<AZ::SerializeContext*>(context); serializeContext != nullptr)
         {
-            serializeContext->Class<Spawnable, AZ::Data::AssetData>()->Version(1)
+            serializeContext->Class<Spawnable, AZ::Data::AssetData>()->Version(2)
                 ->Field("Meta data", &Spawnable::m_metaData)
+                ->Field("Entity aliases", &Spawnable::m_entityAliases)
                 ->Field("Entities", &Spawnable::m_entities);
         }
     }
+
+    void Spawnable::EntityAlias::Reflect(AZ::ReflectContext* context)
+    {
+        if (auto* serializeContext = azrtti_cast<AZ::SerializeContext*>(context); serializeContext != nullptr)
+        {
+            serializeContext->Class<Spawnable::EntityAlias>()
+                ->Version(1)
+                ->Field("Spawnable", &EntityAlias::m_spawnable)
+                ->Field("Tag", &EntityAlias::m_tag)
+                ->Field("Source Index", &EntityAlias::m_sourceIndex)
+                ->Field("Target Index", &EntityAlias::m_targetIndex)
+                ->Field("Alias Type", &EntityAlias::m_aliasType)
+                ->Field("Queue Load", &EntityAlias::m_queueLoad);
+        }
+    }
 } // namespace AzFramework

Code/Framework/AzFramework/AzFramework/Spawnable/Spawnable.h

@@ -11,6 +11,7 @@
 #include <AzCore/Asset/AssetCommon.h>
 #include <AzCore/Component/Entity.h>
 #include <AzCore/Memory/SystemAllocator.h>
+#include <AzCore/std/parallel/atomic.h>
 #include <AzCore/std/containers/vector.h>
 #include <AzCore/std/smart_ptr/unique_ptr.h>
 #include <AzFramework/Spawnable/SpawnableMetaData.h>
@@ -29,7 +30,148 @@ namespace AzFramework
         AZ_CLASS_ALLOCATOR(Spawnable, AZ::SystemAllocator, 0);
         AZ_RTTI(AzFramework::Spawnable, "{855E3021-D305-4845-B284-20C3F7FDF16B}", AZ::Data::AssetData);
 
+        // The order is important for sorting in the SpawnableAssetHandler.
+        enum class EntityAliasType : uint8_t
+        {
+            Original,   //!< The original entity is spawned.
+            Disable,    //!< No entity will be spawned.
+            Replace,    //!< The entity alias is spawned instead of the original.
+            Additional, //!< The original entity is spawned as well as the alias. The alias will get a new entity id.
+            Merge       //!< The original entity is spawned and the components of the alias are added. The caller is responsible for
+                        //!< maintaining a valid component list.
+        };
+
+        enum ShareState : int32_t
+        {
+            Read = -1,
+            NotShared = 0,
+            ReadWrite = 1
+        };
+
+        //! An entity alias redirects the spawning of an entity to another entity, possibly in another spawnable.
+        struct EntityAlias
+        {
+            AZ_CLASS_ALLOCATOR(EntityAlias, AZ::SystemAllocator, 0);
+            AZ_TYPE_INFO(AzFramework::Spawnable::EntityAlias, "{C8D0C5BC-1F0B-4572-98C1-73B2CA8C9356}");
+
+            bool HasLowerIndex(const EntityAlias& other) const;
+
+            AZ::Data::Asset<Spawnable> m_spawnable; //!< The spawnable containing the target entity to spawn.
+            uint32_t m_tag{ 0 }; //!< A unique tag to identify this alias with.
+            uint32_t m_sourceIndex{ 0 }; //!< The index of the entity in the original spawnable that will be replaced.
+            uint32_t m_targetIndex{ 0 }; //!< The index of the entity in the target spawnable that will be used to replace the original.
+            EntityAliasType m_aliasType{ EntityAliasType::Original }; //!< The kind of replacement.
+            bool m_queueLoad{ false }; //!< Whether or not to automatically queue the spawnable for loading.
+
+            static void Reflect(AZ::ReflectContext* context);
+        };
+
         using EntityList = AZStd::vector<AZStd::unique_ptr<AZ::Entity>>;
+        using EntityAliasList = AZStd::vector<EntityAlias>;
+
+    private:
+        class EntityAliasVisitorBase
+        {
+        protected:
+            bool IsValid(const EntityAliasList* aliases) const;
+
+            bool HasAliases(const EntityAliasList* aliases) const;
+            bool AreAllSpawnablesReady(const EntityAliasList* aliases) const;
+
+            EntityAliasList::const_iterator begin(const EntityAliasList* aliases) const;
+            EntityAliasList::const_iterator end(const EntityAliasList* aliases) const;
+            EntityAliasList::const_iterator cbegin(const EntityAliasList* aliases) const;
+            EntityAliasList::const_iterator cend(const EntityAliasList* aliases) const;
+
+            using ListTargetSpawanblesCallback = AZStd::function<void(const AZ::Data::Asset<Spawnable>& targetSpawnable)>;
+            void ListTargetSpawnables(const EntityAliasList* aliases, const ListTargetSpawanblesCallback& callback) const;
+            void ListTargetSpawnables(const EntityAliasList* aliases, AZ::Crc32 tag, const ListTargetSpawanblesCallback& callback) const;
+        };
+
+    public:
+        class EntityAliasVisitor final : public EntityAliasVisitorBase
+        {
+        public:
+            EntityAliasVisitor(Spawnable& owner, EntityAliasList* m_entityAliasList);
+            ~EntityAliasVisitor();
+
+            EntityAliasVisitor(EntityAliasVisitor&& rhs);
+            EntityAliasVisitor& operator=(EntityAliasVisitor&& rhs);
+
+            EntityAliasVisitor(const EntityAliasVisitor& rhs) = delete;
+            EntityAliasVisitor& operator=(const EntityAliasVisitor& rhs) = delete;
+
+            //! Checks if the visitor was able to retrieve data. This needs to be checked before calling any other functions.
+            bool IsValid() const;
+
+            bool HasAliases() const;
+            bool AreAllSpawnablesReady() const;
+
+            // Modification of aliases is limited to specific changes that can only be done through the available modification functions.
+            // For this reason access through iterators is limited to unmodifiable constant iterators.
+
+            EntityAliasList::const_iterator begin() const;
+            EntityAliasList::const_iterator end() const;
+            EntityAliasList::const_iterator cbegin() const;
+            EntityAliasList::const_iterator cend() const;
+            
+            void ListTargetSpawnables(const ListTargetSpawanblesCallback& callback) const;
+            void ListTargetSpawnables(AZ::Crc32 tag, const ListTargetSpawanblesCallback& callback) const;
+
+            void AddAlias(
+                AZ::Data::Asset<Spawnable> targetSpawnable,
+                AZ::Crc32 tag,
+                uint32_t sourceIndex,
+                uint32_t targetIndex,
+                Spawnable::EntityAliasType aliasType,
+                bool queueLoad);
+
+            using ListSpawnablesRequiringLoadCallback = AZStd::function<void(AZ::Data::Asset<Spawnable>& spawnablePendingLoad)>;
+            void ListSpawnablesRequiringLoad(const ListSpawnablesRequiringLoadCallback& callback);
+
+            using UpdateCallback = AZStd::function<void(
+                Spawnable::EntityAliasType& aliasType,
+                bool& queueLoad,
+                const AZ::Data::Asset<Spawnable>& aliasedSpawnable,
+                const AZ::Crc32 tag,
+                const uint32_t sourceIndex,
+                const uint32_t targetIndex)>;
+            void UpdateAliases(const UpdateCallback& callback);
+            void UpdateAliases(AZ::Crc32 tag, const UpdateCallback& callback);
+            void UpdateAliasType(uint32_t index, Spawnable::EntityAliasType newType);
+
+            void Optimize();
+
+        private:
+            Spawnable& m_owner;
+            EntityAliasList* m_entityAliasList{ nullptr };
+            bool m_dirty{ false };
+        };
+
+        class EntityAliasConstVisitor final : public EntityAliasVisitorBase
+        {
+        public:
+            EntityAliasConstVisitor(const Spawnable& owner, const EntityAliasList* entityAliasList);
+            ~EntityAliasConstVisitor();
+
+            //! Checks if the visitor was able to retrieve data. This needs to be checked before calling any other functions.
+            bool IsValid() const;
+
+            bool HasAliases() const;
+            bool AreAllSpawnablesReady() const;
+
+            EntityAliasList::const_iterator begin() const;
+            EntityAliasList::const_iterator end() const;
+            EntityAliasList::const_iterator cbegin() const;
+            EntityAliasList::const_iterator cend() const;
+
+            void ListTargetSpawnables(const ListTargetSpawanblesCallback& callback) const;
+            void ListTargetSpawnables(AZ::Crc32 tag, const ListTargetSpawanblesCallback& callback) const;
+
+        private:
+            const Spawnable& m_owner;
+            const EntityAliasList* m_entityAliasList;
+        };
 
         inline static constexpr const char* FileExtension = "spawnable";
         inline static constexpr const char* DotFileExtension = ".spawnable";
@@ -45,6 +187,9 @@ namespace AzFramework
 
         const EntityList& GetEntities() const;
         EntityList& GetEntities();
+        EntityAliasConstVisitor TryGetAliasesConst() const;
+        EntityAliasConstVisitor TryGetAliases() const;
+        EntityAliasVisitor TryGetAliases();
         bool IsEmpty() const;
 
         SpawnableMetaData& GetMetaData();
@@ -55,11 +200,12 @@ namespace AzFramework
     private:
         SpawnableMetaData m_metaData;
 
+        // Aliases that optionally replace the ones stored in this spawnable.
+        EntityAliasList m_entityAliases;
         // Container for keeping all entities of the prefab the Spawnable was created from.
         // Includes both direct and nested entities of the prefab.
         EntityList m_entities;
+
+        mutable AZStd::atomic<int32_t> m_shareState{ ShareState::NotShared };
     };
-
-    using SpawnableList = AZStd::vector<Spawnable>;
-
 } // namespace AzFramework

Code/Framework/AzFramework/AzFramework/Spawnable/SpawnableAssetBus.h

@@ -0,0 +1,38 @@
+/*
+ * Copyright (c) Contributors to the Open 3D Engine Project.
+ * For complete copyright and license terms please see the LICENSE at the root of this distribution.
+ *
+ * SPDX-License-Identifier: Apache-2.0 OR MIT
+ *
+ */
+
+#pragma once
+
+#include <AzCore/EBus/EBus.h>
+#include <AzCore/std/parallel/mutex.h>
+#include <AzFramework/Spawnable/Spawnable.h>
+
+namespace AzFramework
+{
+    class SpawnableAssetEvents : public AZ::EBusTraits
+    {
+    public:
+        using MutexType = AZStd::recursive_mutex;
+
+        //! Callback to allow the entity aliases in a spawnable to adjusted based on runtime requirements.
+        //! This will be called by the Asset Manager as part of the creation of the spawnable asset from loaded file data. Any work done
+        //! in this callback will be counted towards the maximum amount of time allocated to asset handlers to construct their assets,
+        //! it's recommended to keep work done in this callback to a minimum and prefer delaying any complex processing.
+        //!
+        //! ALERT: Do not start blocking asset requests in this callback.
+        //!     Since this is part of the Asset Manager's asset streaming, doing a blocking load in this callback will cause the job
+        //!     processing the spawnable asset to locked out of doing any asset streaming work. If there are more spawnables doing
+        //!     this than there are job threads available the engine will enter a deadlock situation as no more assets can complete
+        //!     loading and no job threads become free as they're all waiting for assets to complete. It is however safe to queue
+        //!     an asset for loading.
+        virtual void OnResolveAliases(
+            Spawnable::EntityAliasVisitor& aliases, const SpawnableMetaData& metadata, const Spawnable::EntityList& entities) = 0;
+    };
+
+    using SpawnableAssetEventsBus = AZ::EBus<SpawnableAssetEvents>;
+} // namespace AzFramework

Code/Framework/AzFramework/AzFramework/Spawnable/SpawnableAssetHandler.cpp

@@ -9,8 +9,10 @@
 #include <AzCore/Casting/lossy_cast.h>
 #include <AzCore/Serialization/Utils.h>
 #include <AzCore/std/string/string.h>
+#include <AzCore/std/sort.h>
 #include <AzFramework/Spawnable/Spawnable.h>
 #include <AzFramework/Spawnable/SpawnableAssetHandler.h>
+#include <AzFramework/Spawnable/SpawnableAssetBus.h>
 
 namespace AzFramework
 {
@@ -52,6 +54,7 @@ namespace AzFramework
         AZ::ObjectStream::FilterDescriptor filter(assetLoadFilterCB);
         if (AZ::Utils::LoadObjectFromStreamInPlace(*stream, *spawnable, nullptr /*SerializeContext*/, filter))
         {
+            ResolveEntityAliases(spawnable, asset, stream->GetStreamingDeadline(), stream->GetStreamingPriority(), assetLoadFilterCB);
             return AZ::Data::AssetHandler::LoadResult::LoadComplete;
         }
         else
@@ -91,4 +94,41 @@ namespace AzFramework
         AZ::Uuid subIdHash = AZ::Uuid::CreateData(id.data(), id.size());
         return azlossy_caster(subIdHash.GetHash());
     }
+
+    void SpawnableAssetHandler::ResolveEntityAliases(
+        Spawnable* spawnable,
+        [[maybe_unused]] const AZ::Data::Asset<AZ::Data::AssetData>& asset,
+        AZStd::chrono::milliseconds streamingDeadline,
+        AZ::IO::IStreamerTypes::Priority streamingPriority,
+        const AZ::Data::AssetFilterCB& assetLoadFilterCB)
+    {
+        Spawnable::EntityAliasVisitor aliases = spawnable->TryGetAliases();
+        AZ_Assert(aliases.IsValid(), "Newly created Spawnable '%s' was already locked.", asset.GetHint().c_str());
+        if (aliases.HasAliases())
+        {
+            AZ_Assert(
+                AZStd::is_sorted(
+                    aliases.begin(), aliases.end(),
+                    [](const Spawnable::EntityAlias& lhs, const Spawnable::EntityAlias& rhs)
+                    {
+                        return lhs.HasLowerIndex(rhs);
+                    }),
+                "Spawnable '%s' has an unsorted entity alias list.", asset.GetHint().c_str());
+
+            SpawnableAssetEventsBus::Broadcast(
+                &SpawnableAssetEvents::OnResolveAliases, aliases, spawnable->GetMetaData(), spawnable->GetEntities());
+
+            // The aliases will only be optimized if OnResolveAliases has made any changes.
+            aliases.Optimize();
+            aliases.ListSpawnablesRequiringLoad(
+                [&assetLoadFilterCB, streamingDeadline, streamingPriority](AZ::Data::Asset<Spawnable>& assetPendingLoad)
+                {
+                    AZ::Data::AssetLoadParameters loadInfo;
+                    loadInfo.m_assetLoadFilterCB = assetLoadFilterCB;
+                    loadInfo.m_deadline = streamingDeadline;
+                    loadInfo.m_priority = streamingPriority;
+                    assetPendingLoad.QueueLoad(loadInfo);
+                });
+        }
+    }
 } // namespace AzFramework

Code/Framework/AzFramework/AzFramework/Spawnable/SpawnableAssetHandler.h

@@ -50,5 +50,13 @@ namespace AzFramework
             const AZ::Data::Asset<AZ::Data::AssetData>& asset,
             AZStd::shared_ptr<AZ::Data::AssetDataStream> stream,
             const AZ::Data::AssetFilterCB& assetLoadFilterCB) override;
+
+    private:
+        void ResolveEntityAliases(
+            class Spawnable* spawnable,
+            const AZ::Data::Asset<AZ::Data::AssetData>& asset,
+            AZStd::chrono::milliseconds streamingDeadline,
+            AZ::IO::IStreamerTypes::Priority streamingPriority,
+            const AZ::Data::AssetFilterCB& assetLoadFilterCB);
     };
 } // namespace AzFramework

Code/Framework/AzFramework/AzFramework/Spawnable/SpawnableEntitiesContainer.cpp

@@ -26,7 +26,7 @@ namespace AzFramework
         return m_threadData != nullptr;
     }
 
-    uint64_t SpawnableEntitiesContainer::GetCurrentGeneration() const
+    uint32_t SpawnableEntitiesContainer::GetCurrentGeneration() const
     {
         return m_currentGeneration;
     }
@@ -37,7 +37,7 @@ namespace AzFramework
         SpawnableEntitiesInterface::Get()->SpawnAllEntities(m_threadData->m_spawnedEntitiesTicket);
     }
 
-    void SpawnableEntitiesContainer::SpawnEntities(AZStd::vector<size_t> entityIndices)
+    void SpawnableEntitiesContainer::SpawnEntities(AZStd::vector<uint32_t> entityIndices)
     {
         AZ_Assert(m_threadData, "Calling SpawnEntities on a Spawnable container that's not set.");
         SpawnableEntitiesInterface::Get()->SpawnEntities(
@@ -78,15 +78,21 @@ namespace AzFramework
         }
     }
 
-    void SpawnableEntitiesContainer::Alert(AlertCallback callback)
+    void SpawnableEntitiesContainer::Alert(AlertCallback callback, CheckIfSpawnableIsLoaded spawnableCheck)
     {
         AZ_Assert(m_threadData, "Calling DespawnEntities on a Spawnable container that's not set.");
-        SpawnableEntitiesInterface::Get()->Barrier(
-            m_threadData->m_spawnedEntitiesTicket,
-            [generation = m_threadData->m_generation, callback = AZStd::move(callback)](EntitySpawnTicket::Id)
-            {
-                callback(generation);
-            });
+        auto callbackWrapper = [generation = m_threadData->m_generation, callback = AZStd::move(callback)](EntitySpawnTicket::Id)
+        {
+            callback(generation);
+        };
+        if (spawnableCheck == CheckIfSpawnableIsLoaded::No)
+        {
+            SpawnableEntitiesInterface::Get()->Barrier(m_threadData->m_spawnedEntitiesTicket, AZStd::move(callbackWrapper));
+        }
+        else
+        {
+            SpawnableEntitiesInterface::Get()->LoadBarrier(m_threadData->m_spawnedEntitiesTicket, AZStd::move(callbackWrapper));
+        }
     }
 
     void SpawnableEntitiesContainer::Connect(AZ::Data::Asset<Spawnable> spawnable)

Code/Framework/AzFramework/AzFramework/Spawnable/SpawnableEntitiesContainer.h

@@ -36,6 +36,12 @@ namespace AzFramework
     public:
         using AlertCallback = AZStd::function<void(uint32_t generation)>;
 
+        enum class CheckIfSpawnableIsLoaded : bool
+        {
+            Yes,
+            No
+        };
+
         //! Constructs a new spawnables entity container that has not been connected.
         SpawnableEntitiesContainer() = default;
         //! Constructs a new spawnables entity container that connects to the provided spawnable.
@@ -48,13 +54,13 @@ namespace AzFramework
         //! Returns a number that identifies the current generation of the container with. The completion callback can still receive
         //!     calls from older generations as processing completes on those. The returned value can be used to help calls tell
         //!     older versions apart from newer ones.
-        [[nodiscard]] uint64_t GetCurrentGeneration() const;
+        [[nodiscard]] uint32_t GetCurrentGeneration() const;
 
         //! Puts in a request to spawn entities using all entities in the provided spawnable as a template.
         void SpawnAllEntities();
         //! Puts in a request to spawn entities using the entities found in the spawnable at the provided indices as a template.
         //! @param entityIndices A list of indices to the entities in the spawnable.
-        void SpawnEntities(AZStd::vector<size_t> entityIndices);
+        void SpawnEntities(AZStd::vector<uint32_t> entityIndices);
         //! Puts in a request to despawn all previous spawned entities.
         void DespawnAllEntities();
 
@@ -73,7 +79,11 @@ namespace AzFramework
         //! other than the calling thread including the main thread. Note that because the alert is queued it can still be called
         //! after the container has been deleted or can be called for a previously assigned spawnable. In the latter case check
         //! if the current generation matches the generation provided with the callback.
-        void Alert(AlertCallback callback);
+        //! @param callback The function called when the alert triggers. This can be called from a different thread than the one that
+        //!     the one that made the call to Alert.
+        //! @param checkSpawnableIsLoaded If true the alert will also block until the spawnable has been loaded. If false then it will
+        //!     be called after all previous calls have completed, but the spawnable may not be loaded at that point.
+        void Alert(AlertCallback callback, CheckIfSpawnableIsLoaded spawnableCheck = CheckIfSpawnableIsLoaded::No);
 
     private:
         void Connect(AZ::Data::Asset<Spawnable> spawnable);

Code/Framework/AzFramework/AzFramework/Spawnable/SpawnableEntitiesInterface.cpp

@@ -152,7 +152,7 @@ namespace AzFramework
     // SpawnableIndexEntityPair
     //
 
-    SpawnableIndexEntityPair::SpawnableIndexEntityPair(AZ::Entity** entityIterator, size_t* indexIterator)
+    SpawnableIndexEntityPair::SpawnableIndexEntityPair(AZ::Entity** entityIterator, uint32_t* indexIterator)
         : m_entity(entityIterator)
         , m_index(indexIterator)
     {
@@ -168,7 +168,7 @@ namespace AzFramework
         return *m_entity;
     }
 
-    size_t SpawnableIndexEntityPair::GetIndex() const
+    uint32_t SpawnableIndexEntityPair::GetIndex() const
     {
         return *m_index;
     }
@@ -177,7 +177,7 @@ namespace AzFramework
     // SpawnableIndexEntityIterator
     //
 
-    SpawnableIndexEntityIterator::SpawnableIndexEntityIterator(AZ::Entity** entityIterator, size_t* indexIterator)
+    SpawnableIndexEntityIterator::SpawnableIndexEntityIterator(AZ::Entity** entityIterator, uint32_t* indexIterator)
         : m_value(entityIterator, indexIterator)
     {
     }
@@ -248,7 +248,7 @@ namespace AzFramework
     //
 
     SpawnableConstIndexEntityContainerView::SpawnableConstIndexEntityContainerView(
-        AZ::Entity** beginEntity, size_t* beginIndices, size_t length)
+        AZ::Entity** beginEntity, uint32_t* beginIndices, size_t length)
         : m_begin(beginEntity, beginIndices)
         , m_end(beginEntity + length, beginIndices + length)
     {

Code/Framework/AzFramework/AzFramework/Spawnable/SpawnableEntitiesInterface.h

@@ -85,19 +85,19 @@ namespace AzFramework
 
         AZ::Entity* GetEntity();
         const AZ::Entity* GetEntity() const;
-        size_t GetIndex() const;
+        uint32_t GetIndex() const;
 
     private:
         SpawnableIndexEntityPair() = default;
         SpawnableIndexEntityPair(const SpawnableIndexEntityPair&) = default;
         SpawnableIndexEntityPair(SpawnableIndexEntityPair&&) = default;
-        SpawnableIndexEntityPair(AZ::Entity** entityIterator, size_t* indexIterator);
+        SpawnableIndexEntityPair(AZ::Entity** entityIterator, uint32_t* indexIterator);
 
         SpawnableIndexEntityPair& operator=(const SpawnableIndexEntityPair&) = default;
         SpawnableIndexEntityPair& operator=(SpawnableIndexEntityPair&&) = default;
 
         AZ::Entity** m_entity { nullptr };
-        size_t* m_index { nullptr };
+        uint32_t* m_index { nullptr };
     };
 
     class SpawnableIndexEntityIterator
@@ -110,7 +110,7 @@ namespace AzFramework
         using pointer = SpawnableIndexEntityPair*;
         using reference = SpawnableIndexEntityPair&;
 
-        SpawnableIndexEntityIterator(AZ::Entity** entityIterator, size_t* indexIterator);
+        SpawnableIndexEntityIterator(AZ::Entity** entityIterator, uint32_t* indexIterator);
 
         SpawnableIndexEntityIterator& operator++();
         SpawnableIndexEntityIterator operator++(int);
@@ -132,7 +132,7 @@ namespace AzFramework
     class SpawnableConstIndexEntityContainerView
     {
     public:
-        SpawnableConstIndexEntityContainerView(AZ::Entity** beginEntity, size_t* beginIndices, size_t length);
+        SpawnableConstIndexEntityContainerView(AZ::Entity** beginEntity, uint32_t* beginIndices, size_t length);
 
         const SpawnableIndexEntityIterator& begin();
         const SpawnableIndexEntityIterator& end();
@@ -144,6 +144,16 @@ namespace AzFramework
         SpawnableIndexEntityIterator m_end;
     };
 
+    //! Information used when updating the type of an entity alias.
+    struct EntityAliasTypeChange
+    {
+        //! The index of the alias in the spawnable. Note that due to optimizations done on the entity aliases the index of an alias
+        //! can change over time.
+        uint32_t m_aliasIndex;
+        //! The type to replace type stored in the spawnable at the index provided by m_aliasIndex.
+        Spawnable::EntityAliasType m_newAliasType;
+    };
+
     //! Requests to the SpawnableEntitiesInterface require a ticket with a valid spawnable that is used as a template. A ticket can
     //! be reused for multiple calls on the same spawnable and is safe to be used by multiple threads at the same time. Entities created
     //! from the spawnable may be tracked by the ticket and so using the same ticket is needed to despawn the exact entities created
@@ -178,6 +188,7 @@ namespace AzFramework
     using EntityDespawnCallback = AZStd::function<void(EntitySpawnTicket::Id)>;
     using RetrieveEntitySpawnTicketCallback = AZStd::function<void(EntitySpawnTicket*)>;
     using ReloadSpawnableCallback = AZStd::function<void(EntitySpawnTicket::Id, SpawnableConstEntityContainerView)>;
+    using UpdateEntityAliasTypesCallback = AZStd::function<void(EntitySpawnTicket::Id)>;
     using ListEntitiesCallback = AZStd::function<void(EntitySpawnTicket::Id, SpawnableConstEntityContainerView)>;
     using ListIndicesEntitiesCallback = AZStd::function<void(EntitySpawnTicket::Id, SpawnableConstIndexEntityContainerView)>;
     using ClaimEntitiesCallback = AZStd::function<void(EntitySpawnTicket::Id, SpawnableEntityContainerView)>;
@@ -247,6 +258,15 @@ namespace AzFramework
         SpawnablePriority m_priority { SpawnablePriority_Default };
     };
 
+    struct UpdateEntityAliasTypesOptionalArgs final
+    {
+        //! Callback that's called when entity aliases are updated. This can be triggered from a different thread than the one that
+        //!     made the function call to update.
+        UpdateEntityAliasTypesCallback m_completionCallback;
+        //! The priority at which this call will be executed.
+        SpawnablePriority m_priority{ SpawnablePriority_Default };
+    };
+
     struct ListEntitiesOptionalArgs final
     {
         //! The priority at which this call will be executed.
@@ -265,6 +285,14 @@ namespace AzFramework
         SpawnablePriority m_priority{ SpawnablePriority_Default };
     };
 
+    struct LoadBarrierOptionalArgs final
+    {
+        //! The priority at which this call will be executed.
+        SpawnablePriority m_priority{ SpawnablePriority_Default };
+        //! Also checks if the spawnables referenced in the entity aliases that are marked to be loaded are loaded.
+        bool m_checkAliasSpawnables{ true };
+    };
+
     //! Interface definition to (de)spawn entities from a spawnable into the game world.
     //! 
     //! While the callbacks of the individual calls are being processed they will block processing any other request. Callbacks can be
@@ -298,7 +326,7 @@ namespace AzFramework
         //! @param entityIndices The indices into the template entities stored in the spawnable that will be used to spawn entities from.
         //! @param optionalArgs Optional additional arguments, see SpawnEntitiesOptionalArgs.
         virtual void SpawnEntities(
-            EntitySpawnTicket& ticket, AZStd::vector<size_t> entityIndices, SpawnEntitiesOptionalArgs optionalArgs = {}) = 0;
+            EntitySpawnTicket& ticket, AZStd::vector<uint32_t> entityIndices, SpawnEntitiesOptionalArgs optionalArgs = {}) = 0;
         //! Removes all entities in the provided list from the environment.
         //! @param ticket The ticket previously used to spawn entities with.
         //! @param optionalArgs Optional additional arguments, see DespawnAllEntitiesOptionalArgs.
@@ -320,6 +348,16 @@ namespace AzFramework
         virtual void ReloadSpawnable(
             EntitySpawnTicket& ticket, AZ::Data::Asset<Spawnable> spawnable, ReloadSpawnableOptionalArgs optionalArgs = {}) = 0;
 
+        //! Allows updating the entity alias on a spawnable. This allows the spawning behavior for all entities spawned from the used
+        //! spawnable to be changed and is not restricted to this ticket alone.
+        //! @param ticket Holds the information for the spawnable.
+        //! @param updateAliases An array of index and alias type values used to update the entity alias list.
+        //! @param optionalArgs Optional additional arguments, see UpdateEntityAliasTypesOptionalArgs.
+        virtual void UpdateEntityAliasTypes(
+            EntitySpawnTicket& ticket,
+            AZStd::vector<EntityAliasTypeChange> updatedAliases,
+            UpdateEntityAliasTypesOptionalArgs optionalArgs = {}) = 0;
+
         //! List all entities that are spawned using this ticket.
         //! @param ticket Only the entities associated with this ticket will be listed.
         //! @param listCallback Required callback that will be called to list the entities on.
@@ -351,31 +389,37 @@ namespace AzFramework
         //! @param completionCallback Required callback that will be called as soon as the barrier has been reached.
         //! @param optionalArgs Optional additional arguments, see BarrierOptionalArgs.
         virtual void Barrier(EntitySpawnTicket& ticket, BarrierCallback completionCallback, BarrierOptionalArgs optionalArgs = {}) = 0;
+        //! Blocks until the spawnable is loaded and all operations made on the provided ticket before the barrier call have completed.
+        //! @param ticket The ticket to monitor.
+        //! @param completionCallback Required callback that will be called as soon as the barrier has been reached.
+        //! @param optionalArgs Optional additional arguments, see BarrierOptionalArgs.
+        virtual void LoadBarrier(
+            EntitySpawnTicket& ticket, BarrierCallback completionCallback, LoadBarrierOptionalArgs optionalArgs = {}) = 0;
 
     protected:
         [[nodiscard]] virtual AZStd::pair<EntitySpawnTicket::Id, void*> CreateTicket(AZ::Data::Asset<Spawnable>&& spawnable) = 0;
         virtual void DestroyTicket(void* ticket) = 0;
 
         template<typename T>
-        static T& GetTicketPayload(EntitySpawnTicket& ticket)
+        [[nodiscard]] static T& GetTicketPayload(EntitySpawnTicket& ticket)
         {
             return *reinterpret_cast<T*>(ticket.m_payload);
         }
 
         template<typename T>
-        static const T& GetTicketPayload(const EntitySpawnTicket& ticket)
+        [[nodiscard]] static const T& GetTicketPayload(const EntitySpawnTicket& ticket)
         {
             return *reinterpret_cast<const T*>(ticket.m_payload);
         }
 
         template<typename T>
-        static T* GetTicketPayload(EntitySpawnTicket* ticket)
+        [[nodiscard]] static T* GetTicketPayload(EntitySpawnTicket* ticket)
         {
             return reinterpret_cast<T*>(ticket->m_payload);
         }
 
         template<typename T>
-        static const T* GetTicketPayload(const EntitySpawnTicket* ticket)
+        [[nodiscard]] static const T* GetTicketPayload(const EntitySpawnTicket* ticket)
         {
             return reinterpret_cast<const T*>(ticket->m_payload);
         }

Code/Framework/AzFramework/AzFramework/Spawnable/SpawnableEntitiesManager.cpp

@@ -60,7 +60,7 @@ namespace AzFramework
     }
 
     void SpawnableEntitiesManager::SpawnEntities(
-        EntitySpawnTicket& ticket, AZStd::vector<size_t> entityIndices, SpawnEntitiesOptionalArgs optionalArgs)
+        EntitySpawnTicket& ticket, AZStd::vector<uint32_t> entityIndices, SpawnEntitiesOptionalArgs optionalArgs)
     {
         AZ_Assert(ticket.IsValid(), "Ticket provided to SpawnEntities hasn't been initialized.");
 
@@ -128,6 +128,20 @@ namespace AzFramework
         QueueRequest(ticket, optionalArgs.m_priority, AZStd::move(queueEntry));
     }
 
+    void SpawnableEntitiesManager::UpdateEntityAliasTypes(
+        EntitySpawnTicket& ticket,
+        AZStd::vector<EntityAliasTypeChange> updatedAliases,
+        UpdateEntityAliasTypesOptionalArgs optionalArgs)
+    {
+        AZ_Assert(ticket.IsValid(), "Ticket provided to ReloadSpawnable hasn't been initialized.");
+
+        UpdateEntityAliasTypesCommand queueEntry;
+        queueEntry.m_entityAliases = AZStd::move(updatedAliases);
+        queueEntry.m_ticketId = ticket.GetId();
+        queueEntry.m_completionCallback = AZStd::move(optionalArgs.m_completionCallback);
+        QueueRequest(ticket, optionalArgs.m_priority, AZStd::move(queueEntry));
+    }
+
     void SpawnableEntitiesManager::ListEntities(
         EntitySpawnTicket& ticket, ListEntitiesCallback listCallback, ListEntitiesOptionalArgs optionalArgs)
     {
@@ -175,6 +189,19 @@ namespace AzFramework
         QueueRequest(ticket, optionalArgs.m_priority, AZStd::move(queueEntry));
     }
 
+    void SpawnableEntitiesManager::LoadBarrier(
+        EntitySpawnTicket& ticket, BarrierCallback completionCallback, LoadBarrierOptionalArgs optionalArgs)
+    {
+        AZ_Assert(completionCallback, "Load barrier on spawnable entities called without a valid callback to use.");
+        AZ_Assert(ticket.IsValid(), "Ticket provided to LoadBarrier hasn't been initialized.");
+
+        LoadBarrierCommand queueEntry;
+        queueEntry.m_ticketId = ticket.GetId();
+        queueEntry.m_completionCallback = AZStd::move(completionCallback);
+        queueEntry.m_checkAliasSpawnables = optionalArgs.m_checkAliasSpawnables;
+        QueueRequest(ticket, optionalArgs.m_priority, AZStd::move(queueEntry));
+    }
+
     auto SpawnableEntitiesManager::ProcessQueue(CommandQueuePriority priority) -> CommandQueueStatus
     {
         CommandQueueStatus result = CommandQueueStatus::NoCommandsLeft;
@@ -203,13 +230,13 @@ namespace AzFramework
         for (size_t i = 0; i < delayedSize; ++i)
         {
             Requests& request = queue.m_delayed.front();
-            bool result = AZStd::visit(
-                [this](auto&& args) -> bool
+            CommandResult result = AZStd::visit(
+                [this](auto&& args) -> CommandResult
                 {
                     return ProcessRequest(args);
                 },
                 request);
-            if (!result)
+            if (result == CommandResult::Requeue)
             {
                 queue.m_delayed.emplace_back(AZStd::move(request));
             }
@@ -230,13 +257,13 @@ namespace AzFramework
                 while (!pendingRequestQueue.empty())
                 {
                     Requests& request = pendingRequestQueue.front();
-                    bool result = AZStd::visit(
-                        [this](auto&& args) -> bool
+                    CommandResult result = AZStd::visit(
+                        [this](auto&& args) -> CommandResult
                         {
                             return ProcessRequest(args);
                         },
                         request);
-                    if (!result)
+                    if (result == CommandResult::Requeue)
                     {
                         queue.m_delayed.emplace_back(AZStd::move(request));
                     }
@@ -273,14 +300,73 @@ namespace AzFramework
         }
     }
 
-    AZ::Entity* SpawnableEntitiesManager::CloneSingleEntity(const AZ::Entity& entityTemplate,
-        EntityIdMap& templateToCloneMap, AZ::SerializeContext& serializeContext)
+    AZ::Entity* SpawnableEntitiesManager::CloneSingleEntity(const AZ::Entity& entityPrototype,
+        EntityIdMap& prototypeToCloneMap, AZ::SerializeContext& serializeContext)
     {
         // If the same ID gets remapped more than once, preserve the original remapping instead of overwriting it.
         constexpr bool allowDuplicateIds = false;
 
         return AZ::IdUtils::Remapper<AZ::EntityId, allowDuplicateIds>::CloneObjectAndGenerateNewIdsAndFixRefs(
-                &entityTemplate, templateToCloneMap, &serializeContext);
+            &entityPrototype, prototypeToCloneMap, &serializeContext);
+    }
+
+    AZ::Entity* SpawnableEntitiesManager::CloneSingleAliasedEntity(
+        const AZ::Entity& entityPrototype,
+        const Spawnable::EntityAlias& alias,
+        EntityIdMap& prototypeToCloneMap,
+        AZ::Entity* previouslySpawnedEntity,
+        AZ::SerializeContext& serializeContext)
+    {
+        AZ::Entity* clone = nullptr;
+        switch (alias.m_aliasType)
+        {
+        case Spawnable::EntityAliasType::Original:
+            // Behave as the original version.
+            clone = CloneSingleEntity(entityPrototype, prototypeToCloneMap, serializeContext);
+            AZ_Assert(clone != nullptr, "Failed to clone spawnable entity.");
+            return clone;
+        case Spawnable::EntityAliasType::Disable:
+            // Do nothing.
+            return nullptr;
+        case Spawnable::EntityAliasType::Replace:
+            clone = CloneSingleEntity(*(alias.m_spawnable->GetEntities()[alias.m_targetIndex]), prototypeToCloneMap, serializeContext);
+            AZ_Assert(clone != nullptr, "Failed to clone spawnable entity.");
+            return clone;
+        case Spawnable::EntityAliasType::Additional:
+            // The asset handler will have sorted and inserted a Spawnable::EntityAliasType::Original, so the just
+            // spawn the additional entity.
+            clone = CloneSingleEntity(*(alias.m_spawnable->GetEntities()[alias.m_targetIndex]), prototypeToCloneMap, serializeContext);
+            AZ_Assert(clone != nullptr, "Failed to clone spawnable entity.");
+            return clone;
+        case Spawnable::EntityAliasType::Merge:
+            AZ_Assert(previouslySpawnedEntity != nullptr, "Merging components but there's no entity to add to yet.");
+            AppendComponents(
+                *previouslySpawnedEntity, alias.m_spawnable->GetEntities()[alias.m_targetIndex]->GetComponents(), prototypeToCloneMap,
+                serializeContext);
+            return nullptr;
+        default:
+            AZ_Assert(false, "Unsupported spawnable entity alias type: %i", alias.m_aliasType);
+            return nullptr;
+        }
+    }
+
+    void SpawnableEntitiesManager::AppendComponents(
+        AZ::Entity& target,
+        const AZ::Entity::ComponentArrayType& componentPrototypes,
+        EntityIdMap& prototypeToCloneMap,
+        AZ::SerializeContext& serializeContext)
+    {
+        // Only components are added and entities are looked up so no duplicate entity ids should be encountered.
+        constexpr bool allowDuplicateIds = false;
+
+        for (const AZ::Component* component : componentPrototypes)
+        {
+            AZ::Component* clone = AZ::IdUtils::Remapper<AZ::EntityId, allowDuplicateIds>::CloneObjectAndGenerateNewIdsAndFixRefs(
+                component, prototypeToCloneMap, &serializeContext);
+            AZ_Assert(clone, "Unable to clone component for entity '%s' (%zu).", target.GetName().c_str(), target.GetId());
+            [[maybe_unused]] bool result = target.AddComponent(clone);
+            AZ_Assert(result, "Unable to add cloned component to entity '%s' (%zu).", target.GetName().c_str(), target.GetId());
+        }
     }
 
     void SpawnableEntitiesManager::InitializeEntityIdMappings(
@@ -316,161 +402,264 @@ namespace AzFramework
         }
     }
 
-
-    bool SpawnableEntitiesManager::ProcessRequest(SpawnAllEntitiesCommand& request)
+    auto SpawnableEntitiesManager::ProcessRequest(SpawnAllEntitiesCommand& request) -> CommandResult
     {
         Ticket& ticket = *request.m_ticket;
         if (ticket.m_spawnable.IsReady() && request.m_requestId == ticket.m_currentRequestId)
         {
-            AZStd::vector<AZ::Entity*>& spawnedEntities = ticket.m_spawnedEntities;
-            AZStd::vector<size_t>& spawnedEntityIndices = ticket.m_spawnedEntityIndices;
-
-            // Keep track how many entities there were in the array initially
-            size_t spawnedEntitiesInitialCount = spawnedEntities.size();
-
-            // These are 'template' entities we'll be cloning from
-            const Spawnable::EntityList& entitiesToSpawn = ticket.m_spawnable->GetEntities();
-            size_t entitiesToSpawnSize = entitiesToSpawn.size();
-
-            // Reserve buffers
-            spawnedEntities.reserve(spawnedEntities.size() + entitiesToSpawnSize);
-            spawnedEntityIndices.reserve(spawnedEntityIndices.size() + entitiesToSpawnSize);
-
-            // Pre-generate the full set of entity id to new entity id mappings, so that during the clone operation below,
-            // any entity references that point to a not-yet-cloned entity will still get their ids remapped correctly.
-            // We clear out and regenerate the set of IDs on every SpawnAllEntities call, because presumably every entity reference
-            // in every entity we're about to instantiate is intended to point to an entity in our newly-instantiated batch, regardless
-            // of spawn order.  If we didn't clear out the map, it would be possible for some entities here to have references to
-            // previously-spawned entities from a previous SpawnEntities or SpawnAllEntities call.
-            InitializeEntityIdMappings(entitiesToSpawn, ticket.m_entityIdReferenceMap, ticket.m_previouslySpawned);
-
-            for (size_t i = 0; i < entitiesToSpawnSize; ++i)
+            if (Spawnable::EntityAliasConstVisitor aliases = ticket.m_spawnable->TryGetAliasesConst();
+                aliases.IsValid() && aliases.AreAllSpawnablesReady())
             {
-                // If this entity has previously been spawned, give it a new id in the reference map
-                RefreshEntityIdMapping(entitiesToSpawn[i].get()->GetId(), ticket.m_entityIdReferenceMap, ticket.m_previouslySpawned);
+                AZStd::vector<AZ::Entity*>& spawnedEntities = ticket.m_spawnedEntities;
+                AZStd::vector<uint32_t>& spawnedEntityIndices = ticket.m_spawnedEntityIndices;
 
-                AZ::Entity* clone = CloneSingleEntity(*entitiesToSpawn[i], ticket.m_entityIdReferenceMap, *request.m_serializeContext);
-                AZ_Assert(clone != nullptr, "Failed to clone spawnable entity.");
+                // Keep track how many entities there were in the array initially
+                size_t spawnedEntitiesInitialCount = spawnedEntities.size();
 
-                spawnedEntities.emplace_back(clone);
-                spawnedEntityIndices.push_back(i);
-            }
+                // These are 'prototype' entities we'll be cloning from
+                const Spawnable::EntityList& entitiesToSpawn = ticket.m_spawnable->GetEntities();
+                uint32_t entitiesToSpawnSize = aznumeric_caster(entitiesToSpawn.size());
 
-            // loadAll is true if every entity has been spawned only once
-            ticket.m_loadAll = (spawnedEntities.size() == entitiesToSpawnSize);
-            
-            // Let other systems know about newly spawned entities for any pre-processing before adding to the scene/game context.
-            if (request.m_preInsertionCallback)
-            {
-                request.m_preInsertionCallback(request.m_ticketId, SpawnableEntityContainerView(
-                        ticket.m_spawnedEntities.begin() + spawnedEntitiesInitialCount, ticket.m_spawnedEntities.end()));
-            }
+                // Reserve buffers
+                spawnedEntities.reserve(spawnedEntities.size() + entitiesToSpawnSize);
+                spawnedEntityIndices.reserve(spawnedEntityIndices.size() + entitiesToSpawnSize);
 
-            // Add to the game context, now the entities are active
-            for (auto it = ticket.m_spawnedEntities.begin() + spawnedEntitiesInitialCount; it != ticket.m_spawnedEntities.end(); ++it)
-            {
-                (*it)->SetSpawnTicketId(request.m_ticketId);
-                GameEntityContextRequestBus::Broadcast(&GameEntityContextRequestBus::Events::AddGameEntity, *it);
-            }
-
-            // Let other systems know about newly spawned entities for any post-processing after adding to the scene/game context.
-            if (request.m_completionCallback)
-            {
-                request.m_completionCallback(request.m_ticketId, SpawnableConstEntityContainerView(
-                        ticket.m_spawnedEntities.begin() + spawnedEntitiesInitialCount, ticket.m_spawnedEntities.end()));
-            }
-
-            ticket.m_currentRequestId++;
-            return true;
-        }
-        else
-        {
-            return false;
-        }
-    }
-
-    bool SpawnableEntitiesManager::ProcessRequest(SpawnEntitiesCommand& request)
-    {
-        Ticket& ticket = *request.m_ticket;
-        if (ticket.m_spawnable.IsReady() && request.m_requestId == ticket.m_currentRequestId)
-        {
-            AZStd::vector<AZ::Entity*>& spawnedEntities = ticket.m_spawnedEntities;
-            AZStd::vector<size_t>& spawnedEntityIndices = ticket.m_spawnedEntityIndices;
-            AZ_Assert(
-                spawnedEntities.size() == spawnedEntityIndices.size(),
-                "The indices for the spawned entities has gone out of sync with the entities.");
-
-            // Keep track of how many entities there were in the array initially
-            size_t spawnedEntitiesInitialCount = spawnedEntities.size();
-
-            // These are 'template' entities we'll be cloning from
-            const Spawnable::EntityList& entitiesToSpawn = ticket.m_spawnable->GetEntities();
-            size_t entitiesToSpawnSize = request.m_entityIndices.size();
-
-            if (ticket.m_entityIdReferenceMap.empty() || !request.m_referencePreviouslySpawnedEntities)
-            {
-                // This map keeps track of ids from template (spawnable) to clone (instance) allowing patch ups of fields referring
-                // to entityIds outside of a given entity.
-                // We pre-generate the full set of entity id to new entity id mappings, so that during the clone operation below,
+                // Pre-generate the full set of entity-id-to-new-entity-id mappings, so that during the clone operation below,
                 // any entity references that point to a not-yet-cloned entity will still get their ids remapped correctly.
-                // By default, we only initialize this map once because it needs to persist across multiple SpawnEntities calls, so
-                // that reference fixups work even when the entity being referenced is spawned in a different SpawnEntities
-                // (or SpawnAllEntities) call.
-                // However, the caller can also choose to reset the map by passing in "m_referencePreviouslySpawnedEntities = false".
+                // We clear out and regenerate the set of IDs on every SpawnAllEntities call, because presumably every entity reference
+                // in every entity we're about to instantiate is intended to point to an entity in our newly-instantiated batch, regardless
+                // of spawn order.  If we didn't clear out the map, it would be possible for some entities here to have references to
+                // previously-spawned entities from a previous SpawnEntities or SpawnAllEntities call.
                 InitializeEntityIdMappings(entitiesToSpawn, ticket.m_entityIdReferenceMap, ticket.m_previouslySpawned);
-            }
 
-            spawnedEntities.reserve(spawnedEntities.size() + entitiesToSpawnSize);
-            spawnedEntityIndices.reserve(spawnedEntityIndices.size() + entitiesToSpawnSize);
-
-            for (size_t index : request.m_entityIndices)
-            {
-                if (index < entitiesToSpawn.size())
+                auto aliasIt = aliases.begin();
+                auto aliasEnd = aliases.end();
+                if (aliasIt == aliasEnd)
                 {
-                    // If this entity has previously been spawned, give it a new id in the reference map
-                    RefreshEntityIdMapping(
-                        entitiesToSpawn[index].get()->GetId(), ticket.m_entityIdReferenceMap, ticket.m_previouslySpawned);
+                    for (uint32_t i = 0; i < entitiesToSpawnSize; ++i)
+                    {
+                        // If this entity has previously been spawned, give it a new id in the reference map
+                        RefreshEntityIdMapping(
+                            entitiesToSpawn[i].get()->GetId(), ticket.m_entityIdReferenceMap, ticket.m_previouslySpawned);
 
-                    AZ::Entity* clone =
-                        CloneSingleEntity(*entitiesToSpawn[index], ticket.m_entityIdReferenceMap, *request.m_serializeContext);
-                    AZ_Assert(clone != nullptr, "Failed to clone spawnable entity.");
-
-                    spawnedEntities.push_back(clone);
-                    spawnedEntityIndices.push_back(index);
+                        spawnedEntities.emplace_back(
+                            CloneSingleEntity(*entitiesToSpawn[i], ticket.m_entityIdReferenceMap, *request.m_serializeContext));
+                        spawnedEntityIndices.push_back(i);
+                    }
                 }
-            }
-            ticket.m_loadAll = false;
+                else
+                {
+                    for (uint32_t i = 0; i < entitiesToSpawnSize; ++i)
+                    {
+                        // If this entity has previously been spawned, give it a new id in the reference map
+                        RefreshEntityIdMapping(
+                            entitiesToSpawn[i].get()->GetId(), ticket.m_entityIdReferenceMap, ticket.m_previouslySpawned);
 
-            // Let other systems know about newly spawned entities for any pre-processing before adding to the scene/game context.
-            if (request.m_preInsertionCallback)
-            {
-                request.m_preInsertionCallback(request.m_ticketId, SpawnableEntityContainerView(
-                        ticket.m_spawnedEntities.begin() + spawnedEntitiesInitialCount, ticket.m_spawnedEntities.end()));
-            }
+                        if (aliasIt == aliasEnd || aliasIt->m_sourceIndex != i)
+                        {
+                            spawnedEntities.emplace_back(
+                                CloneSingleEntity(*entitiesToSpawn[i], ticket.m_entityIdReferenceMap, *request.m_serializeContext));
+                            spawnedEntityIndices.push_back(i);
+                        }
+                        else
+                        {
+                            // The list of entities has already been sorted and optimized (See SpawnableEntitiesAliasList:Optimize) so can
+                            // be safely executed in order without risking an invalid state.
+                            AZ::Entity* previousEntity = nullptr;
+                            do
+                            {
+                                AZ::Entity* clone = CloneSingleAliasedEntity(
+                                    *entitiesToSpawn[i], *aliasIt, ticket.m_entityIdReferenceMap, previousEntity,
+                                    *request.m_serializeContext);
+                                previousEntity = clone;
+                                if (clone)
+                                {
+                                    spawnedEntities.emplace_back(clone);
+                                    spawnedEntityIndices.push_back(i);
+                                }
+                                ++aliasIt;
+                            } while (aliasIt != aliasEnd && aliasIt->m_sourceIndex == i);
+                        }
+                    }
+                }
 
-            // Add to the game context, now the entities are active
-            for (auto it = ticket.m_spawnedEntities.begin() + spawnedEntitiesInitialCount; it != ticket.m_spawnedEntities.end(); ++it)
-            {
-                (*it)->SetSpawnTicketId(request.m_ticketId);
-                GameEntityContextRequestBus::Broadcast(&GameEntityContextRequestBus::Events::AddGameEntity, *it);
-            }
+                // There were no initial entities then the ticket now holds exactly all entities. If there were already entities then
+                // a new set are not added so it no longer holds exactly the number of entities.
+                ticket.m_loadAll = spawnedEntitiesInitialCount == 0;
 
-            if (request.m_completionCallback)
-            {
-                request.m_completionCallback(request.m_ticketId, SpawnableConstEntityContainerView(
-                    ticket.m_spawnedEntities.begin() + spawnedEntitiesInitialCount, ticket.m_spawnedEntities.end()));
-            }
+                auto newEntitiesBegin = ticket.m_spawnedEntities.begin() + spawnedEntitiesInitialCount;
+                auto newEntitiesEnd = ticket.m_spawnedEntities.end();
+                // Let other systems know about newly spawned entities for any pre-processing before adding to the scene/game context.
+                if (request.m_preInsertionCallback)
+                {
+                    request.m_preInsertionCallback(request.m_ticketId, SpawnableEntityContainerView(newEntitiesBegin, newEntitiesEnd));
+                }
 
-            ticket.m_currentRequestId++;
-            return true;
-        }
-        else
-        {
-            return false;
+                // Add to the game context, now the entities are active
+                for (auto it = newEntitiesBegin; it != newEntitiesEnd; ++it)
+                {
+                    AZ::Entity* clone = (*it);
+                    // The entity component framework doesn't handle entities without TransformComponent safely.
+                    if (!clone->GetComponents().empty())
+                    {
+                        clone->SetSpawnTicketId(request.m_ticketId);
+                        GameEntityContextRequestBus::Broadcast(&GameEntityContextRequestBus::Events::AddGameEntity, *it);
+                    }
+                }
+
+                // Let other systems know about newly spawned entities for any post-processing after adding to the scene/game context.
+                if (request.m_completionCallback)
+                {
+                    request.m_completionCallback(request.m_ticketId, SpawnableConstEntityContainerView(newEntitiesBegin, newEntitiesEnd));
+                }
+
+                ticket.m_currentRequestId++;
+                return CommandResult::Executed;
+            }
         }
+        return CommandResult::Requeue;
     }
 
-    bool SpawnableEntitiesManager::ProcessRequest(DespawnAllEntitiesCommand& request)
+    auto SpawnableEntitiesManager::ProcessRequest(SpawnEntitiesCommand& request) -> CommandResult
+    {
+        Ticket& ticket = *request.m_ticket;
+        if (ticket.m_spawnable.IsReady() && request.m_requestId == ticket.m_currentRequestId)
+        {
+            if (Spawnable::EntityAliasConstVisitor aliases = ticket.m_spawnable->TryGetAliasesConst();
+                aliases.IsValid() && aliases.AreAllSpawnablesReady())
+            {
+                AZStd::vector<AZ::Entity*>& spawnedEntities = ticket.m_spawnedEntities;
+                AZStd::vector<uint32_t>& spawnedEntityIndices = ticket.m_spawnedEntityIndices;
+                AZ_Assert(
+                    spawnedEntities.size() == spawnedEntityIndices.size(),
+                    "The indices for the spawned entities has gone out of sync with the entities.");
+
+                // Keep track of how many entities there were in the array initially
+                size_t spawnedEntitiesInitialCount = spawnedEntities.size();
+
+                // These are 'prototype' entities we'll be cloning from
+                const Spawnable::EntityList& entitiesToSpawn = ticket.m_spawnable->GetEntities();
+                size_t entitiesToSpawnSize = request.m_entityIndices.size();
+
+                if (ticket.m_entityIdReferenceMap.empty() || !request.m_referencePreviouslySpawnedEntities)
+                {
+                    // This map keeps track of ids from prototype (spawnable) to clone (instance) allowing patch ups of fields referring
+                    // to entityIds outside of a given entity.
+                    // We pre-generate the full set of entity id to new entity id mappings, so that during the clone operation below,
+                    // any entity references that point to a not-yet-cloned entity will still get their ids remapped correctly.
+                    // By default, we only initialize this map once because it needs to persist across multiple SpawnEntities calls, so
+                    // that reference fixups work even when the entity being referenced is spawned in a different SpawnEntities
+                    // (or SpawnAllEntities) call.
+                    // However, the caller can also choose to reset the map by passing in "m_referencePreviouslySpawnedEntities = false".
+                    InitializeEntityIdMappings(entitiesToSpawn, ticket.m_entityIdReferenceMap, ticket.m_previouslySpawned);
+                }
+
+                spawnedEntities.reserve(spawnedEntities.size() + entitiesToSpawnSize);
+                spawnedEntityIndices.reserve(spawnedEntityIndices.size() + entitiesToSpawnSize);
+
+                auto aliasBegin = aliases.begin();
+                auto aliasEnd = aliases.end();
+                if (aliasBegin == aliasEnd)
+                {
+                    for (uint32_t index : request.m_entityIndices)
+                    {
+                        if (index < entitiesToSpawn.size())
+                        {
+                            // If this entity has previously been spawned, give it a new id in the reference map
+                            RefreshEntityIdMapping(
+                                entitiesToSpawn[index].get()->GetId(), ticket.m_entityIdReferenceMap, ticket.m_previouslySpawned);
+
+                            spawnedEntities.push_back(
+                                CloneSingleEntity(*entitiesToSpawn[index], ticket.m_entityIdReferenceMap, *request.m_serializeContext));
+                            spawnedEntityIndices.push_back(index);
+                        }
+                    }
+                }
+                else
+                {
+                    for (uint32_t index : request.m_entityIndices)
+                    {
+                        if (index < entitiesToSpawn.size())
+                        {
+                            // If this entity has previously been spawned, give it a new id in the reference map
+                            RefreshEntityIdMapping(
+                                entitiesToSpawn[index].get()->GetId(), ticket.m_entityIdReferenceMap, ticket.m_previouslySpawned);
+
+                            auto aliasIt = AZStd::lower_bound(
+                                aliasBegin, aliasEnd, index,
+                                [](const Spawnable::EntityAlias& lhs, uint32_t rhs)
+                                {
+                                    return lhs.m_sourceIndex < rhs;
+                                });
+
+                            if (aliasIt == aliasEnd || aliasIt->m_sourceIndex != index)
+                            {
+                                spawnedEntities.emplace_back(
+                                    CloneSingleEntity(*entitiesToSpawn[index], ticket.m_entityIdReferenceMap, *request.m_serializeContext));
+                                spawnedEntityIndices.push_back(index);
+                            }
+                            else
+                            {
+                                // The list of entities has already been sorted and optimized (See SpawnableEntitiesAliasList:Optimize) so
+                                // can be safely executed in order without risking an invalid state.
+                                AZ::Entity* previousEntity = nullptr;
+                                do
+                                {
+                                    AZ::Entity* clone = CloneSingleAliasedEntity(
+                                        *entitiesToSpawn[index], *aliasIt, ticket.m_entityIdReferenceMap, previousEntity,
+                                        *request.m_serializeContext);
+                                    previousEntity = clone;
+                                    if (clone)
+                                    {
+                                        spawnedEntities.emplace_back(clone);
+                                        spawnedEntityIndices.push_back(index);
+                                    }
+
+                                    ++aliasIt;
+                                } while (aliasIt != aliasEnd && aliasIt->m_sourceIndex == index);
+                            }
+                        }
+                    }
+                }
+                ticket.m_loadAll = false;
+
+                // Let other systems know about newly spawned entities for any pre-processing before adding to the scene/game context.
+                if (request.m_preInsertionCallback)
+                {
+                    request.m_preInsertionCallback(
+                        request.m_ticketId,
+                        SpawnableEntityContainerView(
+                            ticket.m_spawnedEntities.begin() + spawnedEntitiesInitialCount, ticket.m_spawnedEntities.end()));
+                }
+
+                // Add to the game context, now the entities are active
+                for (auto it = ticket.m_spawnedEntities.begin() + spawnedEntitiesInitialCount; it != ticket.m_spawnedEntities.end(); ++it)
+                {
+                    AZ::Entity* clone = (*it);
+                    // The entity component framework doesn't handle entities without TransformComponent safely.
+                    if (!clone->GetComponents().empty())
+                    {
+                        clone->SetSpawnTicketId(request.m_ticketId);
+                        GameEntityContextRequestBus::Broadcast(&GameEntityContextRequestBus::Events::AddGameEntity, *it);
+                    }
+                }
+
+                if (request.m_completionCallback)
+                {
+                    request.m_completionCallback(
+                        request.m_ticketId,
+                        SpawnableConstEntityContainerView(
+                            ticket.m_spawnedEntities.begin() + spawnedEntitiesInitialCount, ticket.m_spawnedEntities.end()));
+                }
+
+                ticket.m_currentRequestId++;
+                return CommandResult::Executed;
+            }
+        }
+        return CommandResult::Requeue;
+    }
+
+    auto SpawnableEntitiesManager::ProcessRequest(DespawnAllEntitiesCommand& request) -> CommandResult
     {
         Ticket& ticket = *request.m_ticket;
         if (request.m_requestId == ticket.m_currentRequestId)
@@ -495,15 +684,15 @@ namespace AzFramework
             }
 
             ticket.m_currentRequestId++;
-            return true;
+            return CommandResult::Executed;
         }
         else
         {
-            return false;
+            return CommandResult::Requeue;
         }
     }
 
-    bool SpawnableEntitiesManager::ProcessRequest(DespawnEntityCommand& request)
+    auto SpawnableEntitiesManager::ProcessRequest(DespawnEntityCommand& request) -> CommandResult
     {
         Ticket& ticket = *request.m_ticket;
         if (request.m_requestId == ticket.m_currentRequestId)
@@ -529,15 +718,15 @@ namespace AzFramework
             }
 
             ticket.m_currentRequestId++;
-            return true;
+            return CommandResult::Executed;
         }
         else
         {
-            return false;
+            return CommandResult::Requeue;
         }
     }
 
-    bool SpawnableEntitiesManager::ProcessRequest(ReloadSpawnableCommand& request)
+    auto SpawnableEntitiesManager::ProcessRequest(ReloadSpawnableCommand& request) -> CommandResult
     {
         Ticket& ticket = *request.m_ticket;
         AZ_Assert(ticket.m_spawnable.GetId() == request.m_spawnable.GetId(),
@@ -564,7 +753,7 @@ namespace AzFramework
             // Pre-generate the full set of entity id to new entity id mappings, so that during the clone operation below,
             // any entity references that point to a not-yet-cloned entity will still get their ids remapped correctly.
             // This map is intentionally cleared out and regenerated here to ensure that we're starting fresh with mappings that
-            // match the new set of template entities getting spawned.
+            // match the new set of prototype entities getting spawned.
             InitializeEntityIdMappings(entities, ticket.m_entityIdReferenceMap, ticket.m_previouslySpawned);
 
             if (ticket.m_loadAll)
@@ -574,7 +763,7 @@ namespace AzFramework
                 ticket.m_spawnedEntityIndices.clear();
                 size_t entitiesToSpawnSize = entities.size();
 
-                for (size_t i = 0; i < entitiesToSpawnSize; ++i)
+                for (uint32_t i = 0; i < entitiesToSpawnSize; ++i)
                 {
                     // If this entity has previously been spawned, give it a new id in the reference map
                     RefreshEntityIdMapping(entities[i].get()->GetId(), ticket.m_entityIdReferenceMap, ticket.m_previouslySpawned);
@@ -590,7 +779,7 @@ namespace AzFramework
             {
                 size_t entitiesSize = entities.size();
 
-                for (size_t index : ticket.m_spawnedEntityIndices)
+                for (uint32_t index : ticket.m_spawnedEntityIndices)
                 {
                     // It's possible for the new spawnable to have a different number of entities, so guard against this.
                     // It's also possible that the entities have moved within the spawnable to a new index. This can't be
@@ -616,15 +805,40 @@ namespace AzFramework
 
             ticket.m_currentRequestId++;
 
-            return true;
+            return CommandResult::Executed;
         }
         else
         {
-            return false;
+            return CommandResult::Requeue;
         }
     }
 
-    bool SpawnableEntitiesManager::ProcessRequest(ListEntitiesCommand& request)
+    auto SpawnableEntitiesManager::ProcessRequest(UpdateEntityAliasTypesCommand& request) -> CommandResult
+    {
+        Ticket& ticket = *request.m_ticket;
+        if (ticket.m_spawnable.IsReady() && request.m_requestId == ticket.m_currentRequestId)
+        {
+            if (Spawnable::EntityAliasVisitor aliases = ticket.m_spawnable->TryGetAliases(); aliases.IsValid())
+            {
+                for (EntityAliasTypeChange& replacement : request.m_entityAliases)
+                {
+                    aliases.UpdateAliasType(replacement.m_aliasIndex, replacement.m_newAliasType);
+                }
+                aliases.Optimize();
+
+                if (request.m_completionCallback)
+                {
+                    request.m_completionCallback(request.m_ticketId);
+                }
+
+                ticket.m_currentRequestId++;
+                return CommandResult::Executed;
+            }
+        }
+        return CommandResult::Requeue;
+    }
+
+    auto SpawnableEntitiesManager::ProcessRequest(ListEntitiesCommand& request) -> CommandResult
     {
         Ticket& ticket = *request.m_ticket;
         if (request.m_requestId == ticket.m_currentRequestId)
@@ -632,15 +846,15 @@ namespace AzFramework
             request.m_listCallback(request.m_ticketId, SpawnableConstEntityContainerView(
                 ticket.m_spawnedEntities.begin(), ticket.m_spawnedEntities.end()));
             ticket.m_currentRequestId++;
-            return true;
+            return CommandResult::Executed;
         }
         else
         {
-            return false;
+            return CommandResult::Requeue;
         }
     }
 
-    bool SpawnableEntitiesManager::ProcessRequest(ListIndicesEntitiesCommand& request)
+    auto SpawnableEntitiesManager::ProcessRequest(ListIndicesEntitiesCommand& request) -> CommandResult
     {
         Ticket& ticket = *request.m_ticket;
         if (request.m_requestId == ticket.m_currentRequestId)
@@ -651,15 +865,15 @@ namespace AzFramework
             request.m_listCallback(request.m_ticketId, SpawnableConstIndexEntityContainerView(
                     ticket.m_spawnedEntities.begin(), ticket.m_spawnedEntityIndices.begin(), ticket.m_spawnedEntities.size()));
             ticket.m_currentRequestId++;
-            return true;
+            return CommandResult::Executed;
         }
         else
         {
-            return false;
+            return CommandResult::Requeue;
         }
     }
 
-    bool SpawnableEntitiesManager::ProcessRequest(ClaimEntitiesCommand& request)
+    auto SpawnableEntitiesManager::ProcessRequest(ClaimEntitiesCommand& request) -> CommandResult
     {
         Ticket& ticket = *request.m_ticket;
         if (request.m_requestId == ticket.m_currentRequestId)
@@ -671,15 +885,15 @@ namespace AzFramework
             ticket.m_spawnedEntityIndices.clear();
 
             ticket.m_currentRequestId++;
-            return true;
+            return CommandResult::Executed;
         }
         else
         {
-            return false;
+            return CommandResult::Requeue;
         }
     }
 
-    bool SpawnableEntitiesManager::ProcessRequest(BarrierCommand& request)
+    auto SpawnableEntitiesManager::ProcessRequest(BarrierCommand& request) -> CommandResult
     {
         Ticket& ticket = *request.m_ticket;
         if (request.m_requestId == ticket.m_currentRequestId)
@@ -690,15 +904,39 @@ namespace AzFramework
             }
 
             ticket.m_currentRequestId++;
-            return true;
+            return CommandResult::Executed;
         }
         else
         {
-            return false;
+            return CommandResult::Requeue;
         }
     }
 
-    bool SpawnableEntitiesManager::ProcessRequest(DestroyTicketCommand& request)
+    auto SpawnableEntitiesManager::ProcessRequest(LoadBarrierCommand& request) -> CommandResult
+    {
+        Ticket& ticket = *request.m_ticket;
+        if (ticket.m_spawnable.IsReady() && request.m_requestId == ticket.m_currentRequestId)
+        {
+            if (request.m_checkAliasSpawnables)
+            {
+                if (Spawnable::EntityAliasConstVisitor visitor = ticket.m_spawnable->TryGetAliasesConst();
+                    !visitor.IsValid() || !visitor.AreAllSpawnablesReady())
+                {
+                    return CommandResult::Requeue;
+                }
+            }
+            
+            request.m_completionCallback(request.m_ticketId);
+            ticket.m_currentRequestId++;
+            return CommandResult::Executed;
+        }
+        else
+        {
+            return CommandResult::Requeue;
+        }
+    }
+
+    auto SpawnableEntitiesManager::ProcessRequest(DestroyTicketCommand& request) -> CommandResult
     {
         if (request.m_requestId == request.m_ticket->m_currentRequestId)
         {
@@ -706,19 +944,24 @@ namespace AzFramework
             {
                 if (entity != nullptr)
                 {
-                    // Setting it to 0 is needed to avoid the infite loop between GameEntityContext and SpawnableEntitiesManager.
+                    // Setting it to 0 is needed to avoid the infinite loop between GameEntityContext and SpawnableEntitiesManager.
                     entity->SetSpawnTicketId(0);
                     GameEntityContextRequestBus::Broadcast(
                         &GameEntityContextRequestBus::Events::DestroyGameEntity, entity->GetId());
                 }
+                else
+                {
+                    // Entities without components wouldn't have been send to the GameEntityContext.
+                    delete entity;
+                }
             }
             delete request.m_ticket;
 
-            return true;
+            return CommandResult::Executed;
         }
         else
         {
-            return false;
+            return CommandResult::Requeue;
         }
     }
 } // namespace AzFramework

Code/Framework/AzFramework/AzFramework/Spawnable/SpawnableEntitiesManager.h

@@ -55,13 +55,18 @@ namespace AzFramework
 
         void SpawnAllEntities(EntitySpawnTicket& ticket, SpawnAllEntitiesOptionalArgs optionalArgs = {}) override;
         void SpawnEntities(
-            EntitySpawnTicket& ticket, AZStd::vector<size_t> entityIndices, SpawnEntitiesOptionalArgs optionalArgs = {}) override;
+            EntitySpawnTicket& ticket, AZStd::vector<uint32_t> entityIndices, SpawnEntitiesOptionalArgs optionalArgs = {}) override;
         void DespawnAllEntities(EntitySpawnTicket& ticket, DespawnAllEntitiesOptionalArgs optionalArgs = {}) override;
         void DespawnEntity(AZ::EntityId entityId, EntitySpawnTicket& ticket, DespawnEntityOptionalArgs optionalArgs = {}) override;
         void RetrieveEntitySpawnTicket(EntitySpawnTicket::Id entitySpawnTicketId, RetrieveEntitySpawnTicketCallback callback) override;
         void ReloadSpawnable(
             EntitySpawnTicket& ticket, AZ::Data::Asset<Spawnable> spawnable, ReloadSpawnableOptionalArgs optionalArgs = {}) override;
 
+        void UpdateEntityAliasTypes(
+            EntitySpawnTicket& ticket,
+            AZStd::vector<EntityAliasTypeChange> updatedAliases,
+            UpdateEntityAliasTypesOptionalArgs optionalArgs = {}) override;
+
         void ListEntities(
             EntitySpawnTicket& ticket, ListEntitiesCallback listCallback, ListEntitiesOptionalArgs optionalArgs = {}) override;
         void ListIndicesAndEntities(
@@ -70,6 +75,8 @@ namespace AzFramework
             EntitySpawnTicket& ticket, ClaimEntitiesCallback listCallback, ClaimEntitiesOptionalArgs optionalArgs = {}) override;
 
         void Barrier(EntitySpawnTicket& spawnInfo, BarrierCallback completionCallback, BarrierOptionalArgs optionalArgs = {}) override;
+        void LoadBarrier(
+            EntitySpawnTicket& spawnInfo, BarrierCallback completionCallback, LoadBarrierOptionalArgs optionalArgs = {}) override;
 
         //
         // The following function is thread safe but intended to be run from the main thread.
@@ -78,14 +85,20 @@ namespace AzFramework
         CommandQueueStatus ProcessQueue(CommandQueuePriority priority);
 
     protected:
-        struct Ticket
+        enum class CommandResult : bool
+        {
+            Executed,
+            Requeue
+        };
+
+        struct Ticket final
         {
             AZ_CLASS_ALLOCATOR(Ticket, AZ::ThreadPoolAllocator, 0);
             static constexpr uint32_t Processing = AZStd::numeric_limits<uint32_t>::max();
 
-            //! Map of template entity ids to their associated instance ids.
-            //! Tickets can be used to spawn the same template entities multiple times, in any order, across multiple calls.
-            //! Since template entities can reference other entities, this map is used to fix up those references across calls
+            //! Map of prototype entity ids to their associated instance ids.
+            //! Tickets can be used to spawn the same prototype entities multiple times, in any order, across multiple calls.
+            //! Since prototype entities can reference other entities, this map is used to fix up those references across calls
             //! using the following policy:
             //! - Entities referencing an entity that hasn't been spawned yet will get a reference to the id that *will* be used
             //!   the first time that entity will be spawned.  The reference will be invalid until that entity is spawned, but
@@ -100,14 +113,14 @@ namespace AzFramework
             AZStd::unordered_set<AZ::EntityId> m_previouslySpawned;
 
             AZStd::vector<AZ::Entity*> m_spawnedEntities;
-            AZStd::vector<size_t> m_spawnedEntityIndices;
+            AZStd::vector<uint32_t> m_spawnedEntityIndices;
             AZ::Data::Asset<Spawnable> m_spawnable;
             uint32_t m_nextRequestId{ 0 }; //!< Next id for this ticket.
             uint32_t m_currentRequestId { 0 }; //!< The id for the command that should be executed.
             bool m_loadAll{ true };
         };
 
-        struct SpawnAllEntitiesCommand
+        struct SpawnAllEntitiesCommand final
         {
             EntitySpawnCallback m_completionCallback;
             EntityPreInsertionCallback m_preInsertionCallback;
@@ -116,9 +129,9 @@ namespace AzFramework
             EntitySpawnTicket::Id m_ticketId;
             uint32_t m_requestId;
         };
-        struct SpawnEntitiesCommand
+        struct SpawnEntitiesCommand final
         {
-            AZStd::vector<size_t> m_entityIndices;
+            AZStd::vector<uint32_t> m_entityIndices;
             EntitySpawnCallback m_completionCallback;
             EntityPreInsertionCallback m_preInsertionCallback;
             AZ::SerializeContext* m_serializeContext;
@@ -127,7 +140,7 @@ namespace AzFramework
             uint32_t m_requestId;
             bool m_referencePreviouslySpawnedEntities;
         };
-        struct DespawnAllEntitiesCommand
+        struct DespawnAllEntitiesCommand final
         {
             EntityDespawnCallback m_completionCallback;
             Ticket* m_ticket;
@@ -142,7 +155,7 @@ namespace AzFramework
             EntitySpawnTicket::Id m_ticketId;
             uint32_t m_requestId;
         };
-        struct ReloadSpawnableCommand
+        struct ReloadSpawnableCommand final
         {
             AZ::Data::Asset<Spawnable> m_spawnable;
             ReloadSpawnableCallback m_completionCallback;
@@ -151,35 +164,51 @@ namespace AzFramework
             EntitySpawnTicket::Id m_ticketId;
             uint32_t m_requestId;
         };
-        struct ListEntitiesCommand
+        struct UpdateEntityAliasTypesCommand final
+        {
+            AZStd::vector<EntityAliasTypeChange> m_entityAliases;
+            UpdateEntityAliasTypesCallback m_completionCallback;
+            Ticket* m_ticket;
+            EntitySpawnTicket::Id m_ticketId;
+            uint32_t m_requestId;
+        };
+        struct ListEntitiesCommand final
         {
             ListEntitiesCallback m_listCallback;
             Ticket* m_ticket;
             EntitySpawnTicket::Id m_ticketId;
             uint32_t m_requestId;
         };
-        struct ListIndicesEntitiesCommand
+        struct ListIndicesEntitiesCommand final
         {
             ListIndicesEntitiesCallback m_listCallback;
             Ticket* m_ticket;
             EntitySpawnTicket::Id m_ticketId;
             uint32_t m_requestId;
         };
-        struct ClaimEntitiesCommand
+        struct ClaimEntitiesCommand final
         {
             ClaimEntitiesCallback m_listCallback;
             Ticket* m_ticket;
             EntitySpawnTicket::Id m_ticketId;
             uint32_t m_requestId;
         };
-        struct BarrierCommand
+        struct BarrierCommand final
         {
             BarrierCallback m_completionCallback;
             Ticket* m_ticket;
             EntitySpawnTicket::Id m_ticketId;
             uint32_t m_requestId;
         };
-        struct DestroyTicketCommand
+        struct LoadBarrierCommand final
+        {
+            BarrierCallback m_completionCallback;
+            Ticket* m_ticket;
+            EntitySpawnTicket::Id m_ticketId;
+            uint32_t m_requestId;
+            bool m_checkAliasSpawnables;
+        };
+        struct DestroyTicketCommand final
         {
             Ticket* m_ticket;
             uint32_t m_requestId;
@@ -191,10 +220,12 @@ namespace AzFramework
             DespawnAllEntitiesCommand,
             DespawnEntityCommand,
             ReloadSpawnableCommand,
+            UpdateEntityAliasTypesCommand,
             ListEntitiesCommand,
             ListIndicesEntitiesCommand,
             ClaimEntitiesCommand,
             BarrierCommand,
+            LoadBarrierCommand,
             DestroyTicketCommand>;
 
         struct Queue
@@ -212,18 +243,31 @@ namespace AzFramework
         CommandQueueStatus ProcessQueue(Queue& queue);
 
         AZ::Entity* CloneSingleEntity(
-            const AZ::Entity& entityTemplate, EntityIdMap& templateToCloneMap, AZ::SerializeContext& serializeContext);
+            const AZ::Entity& entityPrototype, EntityIdMap& prototypeToCloneMap, AZ::SerializeContext& serializeContext);
+        AZ::Entity* CloneSingleAliasedEntity(
+            const AZ::Entity& entityPrototype,
+            const Spawnable::EntityAlias& alias,
+            EntityIdMap& prototypeToCloneMap,
+            AZ::Entity* previouslySpawnedEntity,
+            AZ::SerializeContext& serializeContext);
+        void AppendComponents(
+            AZ::Entity& target,
+            const AZ::Entity::ComponentArrayType& componentPrototypes,
+            EntityIdMap& prototypeToCloneMap,
+            AZ::SerializeContext& serializeContext);
         
-        bool ProcessRequest(SpawnAllEntitiesCommand& request);
-        bool ProcessRequest(SpawnEntitiesCommand& request);
-        bool ProcessRequest(DespawnAllEntitiesCommand& request);
-        bool ProcessRequest(DespawnEntityCommand& request);
-        bool ProcessRequest(ReloadSpawnableCommand& request);
-        bool ProcessRequest(ListEntitiesCommand& request);
-        bool ProcessRequest(ListIndicesEntitiesCommand& request);
-        bool ProcessRequest(ClaimEntitiesCommand& request);
-        bool ProcessRequest(BarrierCommand& request);
-        bool ProcessRequest(DestroyTicketCommand& request);
+        CommandResult ProcessRequest(SpawnAllEntitiesCommand& request);
+        CommandResult ProcessRequest(SpawnEntitiesCommand& request);
+        CommandResult ProcessRequest(DespawnAllEntitiesCommand& request);
+        CommandResult ProcessRequest(DespawnEntityCommand& request);
+        CommandResult ProcessRequest(ReloadSpawnableCommand& request);
+        CommandResult ProcessRequest(UpdateEntityAliasTypesCommand& request);
+        CommandResult ProcessRequest(ListEntitiesCommand& request);
+        CommandResult ProcessRequest(ListIndicesEntitiesCommand& request);
+        CommandResult ProcessRequest(ClaimEntitiesCommand& request);
+        CommandResult ProcessRequest(BarrierCommand& request);
+        CommandResult ProcessRequest(LoadBarrierCommand& request);
+        CommandResult ProcessRequest(DestroyTicketCommand& request);
 
         //! Generate a base set of original-to-new entity ID mappings to use during spawning.
         //! Since Entity references get fixed up on an entity-by-entity basis while spawning, it's important to have the complete

Code/Framework/AzFramework/AzFramework/Spawnable/SpawnableSystemComponent.cpp

@@ -72,7 +72,7 @@ namespace AzFramework
 
     uint64_t SpawnableSystemComponent::AssignRootSpawnable(AZ::Data::Asset<Spawnable> rootSpawnable)
     {
-        uint64_t generation = 0;
+        uint32_t generation = 0;
 
         if (m_rootSpawnableId == rootSpawnable.GetId())
         {
@@ -87,16 +87,25 @@ namespace AzFramework
             // Suspend and resume processing in the container that completion calls aren't received until
             // everything has been setup to accept callbacks from the call.
             m_rootSpawnableContainer.Reset(rootSpawnable);
-            m_rootSpawnableContainer.SpawnAllEntities();
             generation = m_rootSpawnableContainer.GetCurrentGeneration();
-            AZ_TracePrintf("Spawnables", "Root spawnable set to '%s' at generation %zu.\n", rootSpawnable.GetHint().c_str(),
-                generation);
+
+            // Don't send out the alert that the root spawnable has been assigned until the spawnable itself is ready. The common
+            // use case is for handlers to do something with the information in the spawnable before the entities get spawned.
+            m_rootSpawnableContainer.Alert(
+                [rootSpawnable](uint32_t generation)
+                {
+                    RootSpawnableNotificationBus::Broadcast(
+                        &RootSpawnableNotificationBus::Events::OnRootSpawnableAssigned, AZStd::move(rootSpawnable), generation);
+                }, SpawnableEntitiesContainer::CheckIfSpawnableIsLoaded::Yes);
+            m_rootSpawnableContainer.SpawnAllEntities();
             m_rootSpawnableContainer.Alert(
                 [newSpawnable = AZStd::move(rootSpawnable)](uint32_t generation)
                 {
                     RootSpawnableNotificationBus::QueueBroadcast(
-                        &RootSpawnableNotificationBus::Events::OnRootSpawnableAssigned, newSpawnable, generation);
+                        &RootSpawnableNotificationBus::Events::OnRootSpawnableReady, AZStd::move(newSpawnable), generation);
                 });
+
+            AZ_TracePrintf("Spawnables", "Root spawnable set to '%s' at generation %zu.\n", rootSpawnable.GetHint().c_str(), generation);     
         }
         else
         {
@@ -132,6 +141,12 @@ namespace AzFramework
         AZ_TracePrintf("Spawnables", "New root spawnable '%s' assigned (generation: %i).\n", rootSpawnable.GetHint().c_str(), generation);
     }
 
+    void SpawnableSystemComponent::OnRootSpawnableReady(
+        [[maybe_unused]] AZ::Data::Asset<Spawnable> rootSpawnable, [[maybe_unused]] uint32_t generation)
+    {
+        AZ_TracePrintf("Spawnables", "Entities from new root spawnable '%s' are ready (generation: %i).\n", rootSpawnable.GetHint().c_str(), generation);
+    }
+
     void SpawnableSystemComponent::OnRootSpawnableReleased([[maybe_unused]] uint32_t generation)
     {
         AZ_TracePrintf("Spawnables", "Generation %i of the root spawnable has been released.\n", generation);

Code/Framework/AzFramework/AzFramework/Spawnable/SpawnableSystemComponent.h

@@ -82,6 +82,7 @@ namespace AzFramework
         //
 
         void OnRootSpawnableAssigned(AZ::Data::Asset<Spawnable> rootSpawnable, uint32_t generation) override;
+        void OnRootSpawnableReady(AZ::Data::Asset<Spawnable> rootSpawnable, uint32_t generation) override;
         void OnRootSpawnableReleased(uint32_t generation) override;
         
     protected:

Code/Framework/AzFramework/AzFramework/Viewport/CameraInput.cpp

@@ -806,12 +806,20 @@ namespace AzFramework
         [[maybe_unused]] float scrollDelta,
         [[maybe_unused]] float deltaTime)
     {
+        const auto pivot = m_pivotFn();
+
+        if (!pivot.has_value())
+        {
+            EndActivation();
+            return targetCamera;
+        }
+
         if (Beginning())
         {
             // as the camera starts, record the camera we would like to end up as
-            m_nextCamera.m_offset = m_offsetFn(m_pivotFn().GetDistance(targetCamera.Translation()));
+            m_nextCamera.m_offset = m_offsetFn(pivot.value().GetDistance(targetCamera.Translation()));
             const auto angles =
-                EulerAngles(AZ::Matrix3x3::CreateFromMatrix3x4(AZ::Matrix3x4::CreateLookAt(targetCamera.Translation(), m_pivotFn())));
+                EulerAngles(AZ::Matrix3x3::CreateFromMatrix3x4(AZ::Matrix3x4::CreateLookAt(targetCamera.Translation(), pivot.value())));
             m_nextCamera.m_pitch = angles.GetX();
             m_nextCamera.m_yaw = angles.GetZ();
             m_nextCamera.m_pivot = targetCamera.m_pivot;

Code/Framework/AzFramework/AzFramework/Viewport/CameraInput.h

@@ -651,7 +651,7 @@ namespace AzFramework
     class FocusCameraInput : public CameraInput
     {
     public:
-        using PivotFn = AZStd::function<AZ::Vector3()>;
+        using PivotFn = AZStd::function<AZStd::optional<AZ::Vector3>()>;
 
         FocusCameraInput(const InputChannelId& focusChannelId, FocusOffsetFn offsetFn);
 

Code/Framework/AzFramework/AzFramework/azframework_files.cmake

@@ -286,6 +286,7 @@ set(FILES
     Spawnable/RootSpawnableInterface.h
     Spawnable/Spawnable.cpp
     Spawnable/Spawnable.h
+    Spawnable/SpawnableAssetBus.h
     Spawnable/SpawnableAssetHandler.h
     Spawnable/SpawnableAssetHandler.cpp
     Spawnable/SpawnableEntitiesContainer.h

Code/Framework/AzFramework/Platform/Windows/AzFramework/Windowing/NativeWindow_Windows.cpp

@@ -11,6 +11,7 @@
 
 #include <AzCore/Module/DynamicModuleHandle.h>
 #include <AzCore/PlatformIncl.h>
+#include <AzCore/std/containers/array.h>
 #include <AzCore/std/string/conversions.h>
 
 namespace AzFramework
@@ -234,14 +235,14 @@ namespace AzFramework
             const UINT rawInputHeaderSize = sizeof(RAWINPUTHEADER);
             GetRawInputData((HRAWINPUT)lParam, RID_INPUT, NULL, &rawInputSize, rawInputHeaderSize);
 
-            LPBYTE rawInputBytes = new BYTE[rawInputSize];
+            AZStd::array<BYTE, sizeof(RAWINPUT)> rawInputBytesArray;
+            LPBYTE rawInputBytes = rawInputBytesArray.data();
             GetRawInputData((HRAWINPUT)lParam, RID_INPUT, rawInputBytes, &rawInputSize, rawInputHeaderSize);
 
             RAWINPUT* rawInput = (RAWINPUT*)rawInputBytes;
             AzFramework::RawInputNotificationBusWindows::Broadcast(
                 &AzFramework::RawInputNotificationBusWindows::Events::OnRawInputEvent, *rawInput);
 
-            delete [] rawInputBytes;
             break;
         }
         case WM_CHAR:

Code/Framework/AzFramework/Tests/InputTests.cpp

@@ -48,6 +48,24 @@ namespace InputUnitTests
         AZStd::unique_ptr<InputSystemComponent> m_inputSystemComponent;
     };
 
+    ////////////////////////////////////////////////////////////////////////////////////////////////
+    TEST_F(InputTest, InputChannelId_ConstExpression_CopyConstructorSuccessfull)
+    {
+        constexpr InputChannelId testInputChannelId1("TestInputChannelId");
+        constexpr InputChannelId testInputChannelId2(testInputChannelId1);
+        static_assert(testInputChannelId1 == testInputChannelId2);
+        EXPECT_EQ(testInputChannelId1, testInputChannelId2);
+    }
+
+    ////////////////////////////////////////////////////////////////////////////////////////////////
+    TEST_F(InputTest, InputDeviceId_ConstExpression_CopyConstructorSuccessfull)
+    {
+        constexpr InputDeviceId testInputDeviceId1("TestInputDeviceId");
+        constexpr InputDeviceId testInputDeviceId2(testInputDeviceId1);
+        static_assert(testInputDeviceId1 == testInputDeviceId2);
+        EXPECT_EQ(testInputDeviceId1, testInputDeviceId2);
+    }
+
     ////////////////////////////////////////////////////////////////////////////////////////////////
     TEST_F(InputTest, InputContext_InitWithDataStruct_InitializationSuccessfull)
     {

Code/Framework/AzFramework/Tests/Mocks/MockSpawnableEntitiesInterface.h

@@ -36,7 +36,7 @@ namespace AzFramework
 
         MOCK_METHOD3(
             SpawnEntities,
-            void(EntitySpawnTicket& ticket, AZStd::vector<size_t> entityIndices, SpawnEntitiesOptionalArgs optionalArgs));
+            void(EntitySpawnTicket& ticket, AZStd::vector<uint32_t> entityIndices, SpawnEntitiesOptionalArgs optionalArgs));
 
         MOCK_METHOD2(DespawnAllEntities, void(EntitySpawnTicket& ticket, DespawnAllEntitiesOptionalArgs optionalArgs));
 
@@ -49,6 +49,13 @@ namespace AzFramework
             ReloadSpawnable,
             void(EntitySpawnTicket& ticket, AZ::Data::Asset<Spawnable> spawnable, ReloadSpawnableOptionalArgs optionalArgs));
 
+        MOCK_METHOD3(
+            UpdateEntityAliasTypes,
+            void(
+                EntitySpawnTicket& ticket,
+                AZStd::vector<EntityAliasTypeChange> updatedAliases,
+                UpdateEntityAliasTypesOptionalArgs optionalArgs));
+
         MOCK_METHOD3(
             ListEntities, void(EntitySpawnTicket& ticket, ListEntitiesCallback listCallback, ListEntitiesOptionalArgs optionalArgs));
 
@@ -61,6 +68,7 @@ namespace AzFramework
             void(EntitySpawnTicket& ticket, ClaimEntitiesCallback listCallback, ClaimEntitiesOptionalArgs optionalArgs));
 
         MOCK_METHOD3(Barrier, void(EntitySpawnTicket& ticket, BarrierCallback completionCallback, BarrierOptionalArgs optionalArgs));
+        MOCK_METHOD3(LoadBarrier, void(EntitySpawnTicket& ticket, BarrierCallback completionCallback, LoadBarrierOptionalArgs optionalArgs));
 
         MOCK_METHOD1(CreateTicket, AZStd::pair<EntitySpawnTicket::Id, void*>(AZ::Data::Asset<Spawnable>&& spawnable));
         MOCK_METHOD1(DestroyTicket, void(void* ticket));

Code/Framework/AzFramework/Tests/Spawnable/SpawnableEntitiesManagerTests.cpp

@@ -55,6 +55,40 @@ namespace UnitTest
         AZ::EntityId m_entityReference;
     };
 
+    class SourceSpawnableComponent : public AZ::Component
+    {
+    public:
+        AZ_COMPONENT(SourceSpawnableComponent, "{47FF79CE-A95B-420E-8BEB-F1CC58087B87}");
+
+        void Activate() override {}
+        void Deactivate() override {}
+
+        static void Reflect(AZ::ReflectContext* reflection)
+        {
+            if (auto* serializeContext = azrtti_cast<AZ::SerializeContext*>(reflection))
+            {
+                serializeContext->Class<SourceSpawnableComponent, AZ::Component>();
+            }
+        }
+    };
+
+    class TargetSpawnableComponent : public AZ::Component
+    {
+    public:
+        AZ_COMPONENT(TargetSpawnableComponent, "{B4041561-63A7-4E1E-80F1-78C08D497960}");
+
+        void Activate() override {}
+        void Deactivate() override {}
+
+        static void Reflect(AZ::ReflectContext* reflection)
+        {
+            if (auto* serializeContext = azrtti_cast<AZ::SerializeContext*>(reflection))
+            {
+                serializeContext->Class<TargetSpawnableComponent, AZ::Component>();
+            }
+        }
+    };
+
     class SpawnableEntitiesManagerTest : public AllocatorsFixture
     {
     public:
@@ -66,6 +100,8 @@ namespace UnitTest
             AZ::ComponentApplication::Descriptor descriptor;
             m_application->Start(descriptor);
             m_application->RegisterComponentDescriptor(ComponentWithEntityReference::CreateDescriptor());
+            m_application->RegisterComponentDescriptor(SourceSpawnableComponent::CreateDescriptor());
+            m_application->RegisterComponentDescriptor(TargetSpawnableComponent::CreateDescriptor());
 
             // Without this, the user settings component would attempt to save on finalize/shutdown. Since the file is
             // shared across the whole engine, if multiple tests are run in parallel, the saving could cause a crash
@@ -109,10 +145,126 @@ namespace UnitTest
             entities.reserve(numElements);
             for (size_t i=0; i<numElements; ++i)
             {
-                entities.push_back(AZStd::make_unique<AZ::Entity>());
+                auto entry = AZStd::make_unique<AZ::Entity>();
+                entry->AddComponent(aznew SourceSpawnableComponent());
+                entities.push_back(AZStd::move(entry));
             }
         }
 
+        AZ::Data::Asset<AzFramework::Spawnable> CreateTargetSpawnable(size_t numElements)
+        {
+            auto target = aznew AzFramework::Spawnable(
+                AZ::Data::AssetId(AZ::Uuid("{716CD8C3-0BA8-4F32-B579-0EC7C967796F}")), AZ::Data::AssetData::AssetStatus::Ready);
+
+            AzFramework::Spawnable::EntityList& entities = target->GetEntities();
+            entities.reserve(numElements);
+            for (size_t i = 0; i < numElements; ++i)
+            {
+                auto entry = AZStd::make_unique<AZ::Entity>();
+                entry->AddComponent(aznew TargetSpawnableComponent());
+                entities.push_back(AZStd::move(entry));
+            }
+
+            return AZ::Data::Asset<AzFramework::Spawnable>(target, AZ::Data::AssetLoadBehavior::NoLoad);
+        }
+
+        template<size_t AliasCount>
+        void InsertEntityAliases(
+            const AZStd::array<uint32_t, AliasCount>& sourceIds,
+            const AZStd::array<uint32_t, AliasCount>& targetIds,
+            const AZStd::array<AzFramework::Spawnable::EntityAliasType, AliasCount>& aliasTypes,
+            AZ::Data::Asset<AzFramework::Spawnable>* target = nullptr)
+        {
+            AzFramework::Spawnable::EntityAliasVisitor visitor = m_spawnable->TryGetAliases();
+
+            for (uint32_t i = 0; i < AliasCount; ++i)
+            {
+                if (target)
+                {
+                    visitor.AddAlias(*target, AZ::Crc32(i), sourceIds[i], targetIds[i], aliasTypes[i], false);
+                }
+                else
+                {
+                    AZ::Data::Asset<AzFramework::Spawnable> spawnable(
+                        AZ::Data::AssetId(AZ::Uuid("{4CBEC17A-52D6-42D5-9037-F4C05B9CE1D9}"), i), azrtti_typeid<AzFramework::Spawnable>());
+                    visitor.AddAlias(AZStd::move(spawnable), AZ::Crc32(i), sourceIds[i], targetIds[i], aliasTypes[i], false);
+                }
+            }
+        }
+
+        static bool AreAllEntitiesReplaced(AzFramework::SpawnableConstEntityContainerView entities)
+        {
+            for (const AZ::Entity* entity : entities)
+            {
+                if (entity)
+                {
+                    if (entity->FindComponent<SourceSpawnableComponent>() != nullptr ||
+                        entity->FindComponent<TargetSpawnableComponent>() == nullptr)
+                    {
+                        return false;
+                    }
+                }
+                else
+                {
+                    return false;
+                }
+            }
+            return true;
+        }
+
+        static bool IsEveryOtherEntityAReplacement(AzFramework::SpawnableConstEntityContainerView entities)
+        {
+            bool onAlternative = true;
+            for (const AZ::Entity* entity : entities)
+            {
+                if (entity)
+                {
+                    if (onAlternative)
+                    {
+                        if (entity->FindComponent<SourceSpawnableComponent>() == nullptr ||
+                            entity->FindComponent<TargetSpawnableComponent>() != nullptr)
+                        {
+                            return false;
+                        }
+                    }
+                    else
+                    {
+                        if (entity->FindComponent<SourceSpawnableComponent>() != nullptr ||
+                            entity->FindComponent<TargetSpawnableComponent>() == nullptr)
+                        {
+                            return false;
+                        }
+                    }
+                    onAlternative = !onAlternative;
+                }
+                else
+                {
+                    return false;
+                }
+            }
+            return true;
+        }
+
+        static bool AreAllMerged(AzFramework::SpawnableConstEntityContainerView entities)
+        {
+            for (const AZ::Entity* entity : entities)
+            {
+                if (entity)
+                {
+                    if (entity->FindComponent<SourceSpawnableComponent>() == nullptr ||
+                        entity->FindComponent<TargetSpawnableComponent>() == nullptr)
+                    {
+                        return false;
+                    }
+                }
+                else
+                {
+                    return false;
+                }
+            }
+            return true;
+        }
+
         void CreateRecursiveHierarchy()
         {
             AzFramework::Spawnable::EntityList& entities = m_spawnable->GetEntities();
@@ -245,6 +397,30 @@ namespace UnitTest
         TestApplication* m_application { nullptr };
     };
 
+
+    //
+    // Constructors
+    //
+
+    TEST_F(SpawnableEntitiesManagerTest, EntitySpawnTicket_Move_Works)
+    {
+        AzFramework::EntitySpawnTicket ticket1(*m_spawnableAsset);
+        AzFramework::EntitySpawnTicket ticket2(*m_spawnableAsset);
+
+        const AzFramework::EntitySpawnTicket::Id ticket1Id = ticket1.GetId();
+        const AzFramework::EntitySpawnTicket::Id ticket2Id = ticket2.GetId();
+
+        AzFramework::EntitySpawnTicket ticketMoveConstructor(AZStd::move(ticket1));
+        EXPECT_TRUE(ticketMoveConstructor.IsValid());
+        EXPECT_EQ(ticketMoveConstructor.GetId(), ticket1Id);
+
+        AzFramework::EntitySpawnTicket ticketMoveOperator;
+        ticketMoveOperator = AZStd::move(ticket2);
+        EXPECT_TRUE(ticketMoveOperator.IsValid());
+        EXPECT_EQ(ticketMoveOperator.GetId(), ticket2Id);
+    }
+
+
     //
     // SpawnAllEntitities
     //
@@ -366,24 +542,6 @@ namespace UnitTest
         }
     }
 
-    TEST_F(SpawnableEntitiesManagerTest, EntitySpawnTicket_Move_Works)
-    {
-        AzFramework::EntitySpawnTicket ticket1(*m_spawnableAsset);
-        AzFramework::EntitySpawnTicket ticket2(*m_spawnableAsset);
-
-        const AzFramework::EntitySpawnTicket::Id ticket1Id = ticket1.GetId();
-        const AzFramework::EntitySpawnTicket::Id ticket2Id = ticket2.GetId();
-
-        AzFramework::EntitySpawnTicket ticketMoveConstructor(AZStd::move(ticket1));
-        EXPECT_TRUE(ticketMoveConstructor.IsValid());
-        EXPECT_EQ(ticketMoveConstructor.GetId(), ticket1Id);
-
-        AzFramework::EntitySpawnTicket ticketMoveOperator;
-        ticketMoveOperator = AZStd::move(ticket2);
-        EXPECT_TRUE(ticketMoveOperator.IsValid());
-        EXPECT_EQ(ticketMoveOperator.GetId(), ticket2Id);
-    }
-
     TEST_F(SpawnableEntitiesManagerTest, SpawnAllEntities_DeleteTicketBeforeCall_NoCrash)
     {
         {
@@ -393,6 +551,135 @@ namespace UnitTest
         m_manager->ProcessQueue(AzFramework::SpawnableEntitiesManager::CommandQueuePriority::Regular);
     }
 
+    TEST_F(SpawnableEntitiesManagerTest, SpawnAllEntities_AllAliasesWithDisabled_NoEntitiesSpawned)
+    {
+        using namespace AzFramework;
+        static constexpr size_t NumEntities = 4;
+        FillSpawnable(NumEntities);
+        InsertEntityAliases<NumEntities>(
+            { 0, 1, 2, 3 }, { 0, 1, 2, 3 },
+            { Spawnable::EntityAliasType::Disable, Spawnable::EntityAliasType::Disable, Spawnable::EntityAliasType::Disable,
+              Spawnable::EntityAliasType::Disable });
+
+        size_t spawnedEntitiesCount = 0;
+        auto callback = [&spawnedEntitiesCount](AzFramework::EntitySpawnTicket::Id, AzFramework::SpawnableConstEntityContainerView entities)
+        {
+            spawnedEntitiesCount += entities.size();
+        };
+        AzFramework::SpawnAllEntitiesOptionalArgs optionalArgs;
+        optionalArgs.m_completionCallback = AZStd::move(callback);
+        m_manager->SpawnAllEntities(*m_ticket, AZStd::move(optionalArgs));
+        m_manager->ProcessQueue(AzFramework::SpawnableEntitiesManager::CommandQueuePriority::Regular);
+
+        EXPECT_EQ(0, spawnedEntitiesCount);
+    }
+
+    TEST_F(SpawnableEntitiesManagerTest, SpawnAllEntities_SomeAliasesWithDisabled_RegularEntitiesAreSpawned)
+    {
+        using namespace AzFramework;
+        static constexpr size_t NumEntities = 8;
+        FillSpawnable(NumEntities);
+        InsertEntityAliases<2>({ 1, 3 }, { 1, 3 }, { Spawnable::EntityAliasType::Disable, Spawnable::EntityAliasType::Disable });
+
+        size_t spawnedEntitiesCount = 0;
+        auto callback = [&spawnedEntitiesCount](AzFramework::EntitySpawnTicket::Id, AzFramework::SpawnableConstEntityContainerView entities)
+        {
+            spawnedEntitiesCount += entities.size();
+        };
+        AzFramework::SpawnAllEntitiesOptionalArgs optionalArgs;
+        optionalArgs.m_completionCallback = AZStd::move(callback);
+        m_manager->SpawnAllEntities(*m_ticket, AZStd::move(optionalArgs));
+        m_manager->ProcessQueue(AzFramework::SpawnableEntitiesManager::CommandQueuePriority::Regular);
+
+        EXPECT_EQ(6, spawnedEntitiesCount);
+    }
+
+    TEST_F(SpawnableEntitiesManagerTest, SpawnAllEntities_AllAliasesWithReplace_EntitiesSpawnedFromTarget)
+    {
+        using namespace AzFramework;
+        static constexpr size_t NumEntities = 4;
+        FillSpawnable(NumEntities);
+        AZ::Data::Asset<Spawnable> target = CreateTargetSpawnable(4);
+        InsertEntityAliases<4>(
+            { 0, 1, 2, 3 }, { 0, 1, 2, 3 },
+            { Spawnable::EntityAliasType::Replace, Spawnable::EntityAliasType::Replace, Spawnable::EntityAliasType::Replace,
+              Spawnable::EntityAliasType::Replace },
+            &target);
+
+        size_t spawnedEntitiesCount = 0;
+        bool allReplaced = false;
+        auto callback = [&spawnedEntitiesCount, &allReplaced](
+            AzFramework::EntitySpawnTicket::Id, AzFramework::SpawnableConstEntityContainerView entities)
+        {
+            spawnedEntitiesCount += entities.size();
+            allReplaced = AreAllEntitiesReplaced(entities);
+        };
+        AzFramework::SpawnAllEntitiesOptionalArgs optionalArgs;
+        optionalArgs.m_completionCallback = AZStd::move(callback);
+        m_manager->SpawnAllEntities(*m_ticket, AZStd::move(optionalArgs));
+        m_manager->ProcessQueue(AzFramework::SpawnableEntitiesManager::CommandQueuePriority::Regular);
+
+        EXPECT_EQ(4, spawnedEntitiesCount);
+        EXPECT_TRUE(allReplaced);
+    }
+
+    TEST_F(SpawnableEntitiesManagerTest, SpawnAllEntities_AllAliasesWithAdditional_SourceAndTargetComponentsMerged)
+    {
+        using namespace AzFramework;
+        static constexpr size_t NumEntities = 4;
+        FillSpawnable(NumEntities);
+        AZ::Data::Asset<Spawnable> target = CreateTargetSpawnable(4);
+        InsertEntityAliases<4>(
+            { 0, 1, 2, 3 }, { 0, 1, 2, 3 },
+            { Spawnable::EntityAliasType::Additional, Spawnable::EntityAliasType::Additional, Spawnable::EntityAliasType::Additional,
+              Spawnable::EntityAliasType::Additional },
+            &target);
+
+        size_t spawnedEntitiesCount = 0;
+        bool allAdded = false;
+        auto callback = [&spawnedEntitiesCount, &allAdded](
+            AzFramework::EntitySpawnTicket::Id, AzFramework::SpawnableConstEntityContainerView entities)
+        {
+            spawnedEntitiesCount += entities.size();
+            allAdded = IsEveryOtherEntityAReplacement(entities);
+        };
+        AzFramework::SpawnAllEntitiesOptionalArgs optionalArgs;
+        optionalArgs.m_completionCallback = AZStd::move(callback);
+        m_manager->SpawnAllEntities(*m_ticket, AZStd::move(optionalArgs));
+        m_manager->ProcessQueue(AzFramework::SpawnableEntitiesManager::CommandQueuePriority::Regular);
+
+        EXPECT_EQ(8, spawnedEntitiesCount);
+        EXPECT_TRUE(allAdded);
+    }
+
+    TEST_F(SpawnableEntitiesManagerTest, SpawnAllEntities_AllAliasesWithMerge_SourceAndTargetComponentsMerged)
+    {
+        using namespace AzFramework;
+        static constexpr size_t NumEntities = 4;
+        FillSpawnable(NumEntities);
+        AZ::Data::Asset<Spawnable> target = CreateTargetSpawnable(4);
+        InsertEntityAliases<4>(
+            { 0, 1, 2, 3 }, { 0, 1, 2, 3 },
+            { Spawnable::EntityAliasType::Merge, Spawnable::EntityAliasType::Merge, Spawnable::EntityAliasType::Merge,
+              Spawnable::EntityAliasType::Merge },
+            &target);
+
+        size_t spawnedEntitiesCount = 0;
+        bool allMerged = false;
+        auto callback = [&spawnedEntitiesCount, &allMerged](
+            AzFramework::EntitySpawnTicket::Id, AzFramework::SpawnableConstEntityContainerView entities)
+        {
+            spawnedEntitiesCount += entities.size();
+            allMerged = AreAllMerged(entities);
+        };
+        AzFramework::SpawnAllEntitiesOptionalArgs optionalArgs;
+        optionalArgs.m_completionCallback = AZStd::move(callback);
+        m_manager->SpawnAllEntities(*m_ticket, AZStd::move(optionalArgs));
+        m_manager->ProcessQueue(AzFramework::SpawnableEntitiesManager::CommandQueuePriority::Regular);
+
+        EXPECT_EQ(4, spawnedEntitiesCount);
+        EXPECT_TRUE(allMerged);
+    }
 
     //
     // SpawnEntities
@@ -403,7 +690,7 @@ namespace UnitTest
         static constexpr size_t NumEntities = 4;
         FillSpawnable(NumEntities);
 
-        AZStd::vector<size_t> indices = { 0, 2, 3, 1 };
+        AZStd::vector<uint32_t> indices = { 0, 2, 3, 1 };
 
         size_t spawnedEntitiesCount = 0;
         auto callback = [&spawnedEntitiesCount](AzFramework::EntitySpawnTicket::Id, AzFramework::SpawnableConstEntityContainerView entities)
@@ -423,7 +710,7 @@ namespace UnitTest
         static constexpr size_t NumEntities = 1;
         FillSpawnable(NumEntities);
 
-        AZStd::vector<size_t> indices = { 0, 0 };
+        AZStd::vector<uint32_t> indices = { 0, 0 };
 
         size_t spawnedEntitiesCount = 0;
         auto callback =
@@ -444,7 +731,7 @@ namespace UnitTest
         static constexpr size_t NumEntities = 4;
         FillSpawnable(NumEntities);
 
-        AZStd::vector<size_t> indices = { 0, 2, 3, 1 };
+        AZStd::vector<uint32_t> indices = { 0, 2, 3, 1 };
 
         size_t spawnedEntitiesCount = 0;
         auto callback =
@@ -467,7 +754,7 @@ namespace UnitTest
         FillSpawnable(NumEntities);
         CreateSingleParent();
 
-        AZStd::vector<size_t> indices = { 0, 1, 2, 3 };
+        AZStd::vector<uint32_t> indices = { 0, 1, 2, 3 };
         AZStd::vector<AZ::EntityId> parents;
 
         auto callback = [&parents](AzFramework::EntitySpawnTicket::Id, AzFramework::SpawnableConstEntityContainerView entities)
@@ -499,7 +786,7 @@ namespace UnitTest
         FillSpawnable(NumEntities);
         CreateSingleParent();
 
-        AZStd::vector<size_t> indices = { 0, 1, 2, 3 };
+        AZStd::vector<uint32_t> indices = { 0, 1, 2, 3 };
         AZStd::vector<AZ::EntityId> parents;
 
         auto callback =
@@ -754,6 +1041,148 @@ namespace UnitTest
         m_manager->ProcessQueue(AzFramework::SpawnableEntitiesManager::CommandQueuePriority::Regular);
     }
 
+    TEST_F(SpawnableEntitiesManagerTest, SpawnEntities_AllAliasesWithDisabled_NoEntitiesSpawned)
+    {
+        using namespace AzFramework;
+        static constexpr size_t NumEntities = 4;
+        FillSpawnable(NumEntities);
+
+        InsertEntityAliases<NumEntities>(
+            { 0, 1, 2, 3 }, { 0, 1, 2, 3 },
+            { Spawnable::EntityAliasType::Disable, Spawnable::EntityAliasType::Disable, Spawnable::EntityAliasType::Disable,
+              Spawnable::EntityAliasType::Disable });
+
+        AZStd::vector<uint32_t> indices = { 0, 2, 3, 1 };
+
+        size_t spawnedEntitiesCount = 0;
+        auto callback = [&spawnedEntitiesCount](AzFramework::EntitySpawnTicket::Id, AzFramework::SpawnableConstEntityContainerView entities)
+        {
+            spawnedEntitiesCount += entities.size();
+        };
+        AzFramework::SpawnEntitiesOptionalArgs optionalArgs;
+        optionalArgs.m_completionCallback = AZStd::move(callback);
+        m_manager->SpawnEntities(*m_ticket, AZStd::move(indices), AZStd::move(optionalArgs));
+        m_manager->ProcessQueue(AzFramework::SpawnableEntitiesManager::CommandQueuePriority::Regular);
+
+        EXPECT_EQ(0, spawnedEntitiesCount);
+    }
+
+    TEST_F(SpawnableEntitiesManagerTest, SpawnEntities_SomeAliasesWithDisabled_RegularEntitiesAreSpawned)
+    {
+        using namespace AzFramework;
+        FillSpawnable(8);
+        InsertEntityAliases<3>(
+            { 1, 3, 6 }, { 1, 3, 6 },
+            { Spawnable::EntityAliasType::Disable, Spawnable::EntityAliasType::Disable, Spawnable::EntityAliasType::Disable });
+
+        AZStd::vector<uint32_t> indices = { 0, 2, 3, 1, 2, 3, 0, 1, 6, 4, 5, 7, 4, 1, 0, 6 };
+
+        size_t spawnedEntitiesCount = 0;
+        auto callback = [&spawnedEntitiesCount](AzFramework::EntitySpawnTicket::Id, AzFramework::SpawnableConstEntityContainerView entities)
+        {
+            spawnedEntitiesCount += entities.size();
+        };
+        AzFramework::SpawnEntitiesOptionalArgs optionalArgs;
+        optionalArgs.m_completionCallback = AZStd::move(callback);
+        m_manager->SpawnEntities(*m_ticket, AZStd::move(indices), AZStd::move(optionalArgs));
+        m_manager->ProcessQueue(AzFramework::SpawnableEntitiesManager::CommandQueuePriority::Regular);
+
+        EXPECT_EQ(9, spawnedEntitiesCount);
+    }
+
+    TEST_F(SpawnableEntitiesManagerTest, SpawnEntities_AllAliasesWithReplace_EntitiesSpawnedFromTarget)
+    {
+        using namespace AzFramework;
+        static constexpr size_t NumEntities = 4;
+        FillSpawnable(NumEntities);
+        AZ::Data::Asset<Spawnable> target = CreateTargetSpawnable(4);
+        InsertEntityAliases<4>(
+            { 0, 1, 2, 3 }, { 0, 1, 2, 3 },
+            { Spawnable::EntityAliasType::Replace, Spawnable::EntityAliasType::Replace, Spawnable::EntityAliasType::Replace,
+              Spawnable::EntityAliasType::Replace },
+            &target);
+
+        AZStd::vector<uint32_t> indices = { 0, 2, 3, 1 };
+
+        size_t spawnedEntitiesCount = 0;
+        bool allReplaced = false;
+        auto callback = [&spawnedEntitiesCount, &allReplaced](
+            AzFramework::EntitySpawnTicket::Id, AzFramework::SpawnableConstEntityContainerView entities)
+        {
+            spawnedEntitiesCount += entities.size();
+            allReplaced = AreAllEntitiesReplaced(entities);
+        };
+        AzFramework::SpawnEntitiesOptionalArgs optionalArgs;
+        optionalArgs.m_completionCallback = AZStd::move(callback);
+        m_manager->SpawnEntities(*m_ticket, AZStd::move(indices), AZStd::move(optionalArgs));
+        m_manager->ProcessQueue(AzFramework::SpawnableEntitiesManager::CommandQueuePriority::Regular);
+
+        EXPECT_EQ(4, spawnedEntitiesCount);
+        EXPECT_TRUE(allReplaced);
+    }
+
+    TEST_F(SpawnableEntitiesManagerTest, SpawnEntities_AllAliasesWithAdditional_SourceAndTargetComponentsMerged)
+    {
+        using namespace AzFramework;
+        static constexpr size_t NumEntities = 4;
+        FillSpawnable(NumEntities);
+        AZ::Data::Asset<Spawnable> target = CreateTargetSpawnable(4);
+        InsertEntityAliases<4>(
+            { 0, 1, 2, 3 }, { 0, 1, 2, 3 },
+            { Spawnable::EntityAliasType::Additional, Spawnable::EntityAliasType::Additional, Spawnable::EntityAliasType::Additional,
+              Spawnable::EntityAliasType::Additional },
+            &target);
+
+        AZStd::vector<uint32_t> indices = { 0, 2, 3, 1 };
+
+        size_t spawnedEntitiesCount = 0;
+        bool allAdded = false;
+        auto callback =
+            [&spawnedEntitiesCount, &allAdded](
+            AzFramework::EntitySpawnTicket::Id, AzFramework::SpawnableConstEntityContainerView entities)
+        {
+            spawnedEntitiesCount += entities.size();
+            allAdded = IsEveryOtherEntityAReplacement(entities);
+        };
+        AzFramework::SpawnEntitiesOptionalArgs optionalArgs;
+        optionalArgs.m_completionCallback = AZStd::move(callback);
+        m_manager->SpawnEntities(*m_ticket, AZStd::move(indices), AZStd::move(optionalArgs));
+        m_manager->ProcessQueue(AzFramework::SpawnableEntitiesManager::CommandQueuePriority::Regular);
+
+        EXPECT_EQ(8, spawnedEntitiesCount);
+        EXPECT_TRUE(allAdded);
+    }
+
+    TEST_F(SpawnableEntitiesManagerTest, SpawnEntities_AllAliasesWithMerge_SourceAndTargetComponentsMerged)
+    {
+        using namespace AzFramework;
+        static constexpr size_t NumEntities = 4;
+        FillSpawnable(NumEntities);
+        AZ::Data::Asset<Spawnable> target = CreateTargetSpawnable(4);
+        InsertEntityAliases<4>(
+            { 0, 1, 2, 3 }, { 0, 1, 2, 3 },
+            { Spawnable::EntityAliasType::Merge, Spawnable::EntityAliasType::Merge, Spawnable::EntityAliasType::Merge,
+              Spawnable::EntityAliasType::Merge },
+            &target);
+
+        AZStd::vector<uint32_t> indices = { 0, 2, 3, 1 };
+
+        size_t spawnedEntitiesCount = 0;
+        bool allMerged = false;
+        auto callback = [&spawnedEntitiesCount, &allMerged](
+            AzFramework::EntitySpawnTicket::Id, AzFramework::SpawnableConstEntityContainerView entities)
+        {
+            spawnedEntitiesCount += entities.size();
+            allMerged = AreAllMerged(entities);
+        };
+        AzFramework::SpawnEntitiesOptionalArgs optionalArgs;
+        optionalArgs.m_completionCallback = AZStd::move(callback);
+        m_manager->SpawnEntities(*m_ticket, AZStd::move(indices), AZStd::move(optionalArgs));
+        m_manager->ProcessQueue(AzFramework::SpawnableEntitiesManager::CommandQueuePriority::Regular);
+
+        EXPECT_EQ(4, spawnedEntitiesCount);
+        EXPECT_TRUE(allMerged);
+    }
 
     //
     // DespawnAllEntities

Code/Framework/AzFramework/Tests/Spawnable/SpawnableTests.cpp

@@ -0,0 +1,513 @@
+/*
+ * Copyright (c) Contributors to the Open 3D Engine Project.
+ * For complete copyright and license terms please see the LICENSE at the root of this distribution.
+ *
+ * SPDX-License-Identifier: Apache-2.0 OR MIT
+ *
+ */
+
+#include <AzCore/Casting/numeric_cast.h>
+#include <AzCore/UnitTest/TestTypes.h>
+#include <AzFramework/Spawnable/Spawnable.h>
+#include <AzTest/AzTest.h>
+
+namespace UnitTest
+{
+    class SpawnableTest : public AllocatorsFixture
+    {
+    public:
+        static constexpr size_t DefaultEntityAliasTestCount = 8;
+
+        void SetUp() override
+        {
+            AllocatorsFixture::SetUp();
+
+            m_spawnable = aznew AzFramework::Spawnable();
+        }
+
+        void TearDown() override
+        {
+            delete m_spawnable;
+            m_spawnable = nullptr;
+
+            AllocatorsFixture::TearDown();
+        }
+
+        void InsertEntities(size_t count)
+        {
+            AzFramework::Spawnable::EntityList& entities = m_spawnable->GetEntities();
+            entities.reserve(entities.size() + count);
+            for (size_t i = 0; i < count; ++i)
+            {
+                entities.emplace_back(AZStd::make_unique<AZ::Entity>());
+            }
+        }
+
+        template<size_t Count>
+        void InsertEntityAliases(
+            const AZStd::array<uint32_t, Count>& sourceIds,
+            const AZStd::array<uint32_t, Count>& targetIds,
+            const AZStd::array<AzFramework::Spawnable::EntityAliasType, Count>& aliasTypes,
+            bool queueLoad = false)
+        {
+            AzFramework::Spawnable::EntityAliasVisitor visitor = m_spawnable->TryGetAliases();
+
+            for (uint32_t i = 0; i < Count; ++i)
+            {
+                AZ::Data::Asset<AzFramework::Spawnable> spawnable(
+                    AZ::Data::AssetId(AZ::Uuid("{4CBEC17A-52D6-42D5-9037-F4C05B9CE1D9}"), i), azrtti_typeid<AzFramework::Spawnable>());
+                visitor.AddAlias(spawnable, AZ::Crc32(i), sourceIds[i], targetIds[i], aliasTypes[i], queueLoad);
+            }
+        }
+
+        template<size_t Count>
+        void InsertEntityAliases(bool queueLoad)
+        {
+            using namespace AzFramework;
+
+            AZStd::array<uint32_t, Count> ids;
+            for (uint32_t i=0; i<aznumeric_cast<uint32_t>(Count); ++i)
+            {
+                ids[i] = i;
+            }
+
+            AZStd::array<AzFramework::Spawnable::EntityAliasType, Count> aliasTypes;
+            for (uint32_t i = 0; i < aznumeric_cast<uint32_t>(Count); ++i)
+            {
+                aliasTypes[i] = Spawnable::EntityAliasType::Replace;
+            }
+
+            InsertEntityAliases<Count>(ids, ids, aliasTypes, queueLoad);
+        }
+
+        template<size_t Count>
+        void InsertEntityAliases()
+        {
+            InsertEntityAliases<Count>(false);
+        }
+
+    protected:
+        AzFramework::Spawnable* m_spawnable;
+    };
+
+
+    //
+    // TryGetAliasesConst
+    //
+
+    TEST_F(SpawnableTest, TryGetAliasesConst_GetVisitor_VisitorDataIsAvailable)
+    {
+        AzFramework::Spawnable::EntityAliasConstVisitor visitor = m_spawnable->TryGetAliasesConst();
+        EXPECT_TRUE(visitor.IsValid());
+    }
+
+    TEST_F(SpawnableTest, TryGetAliasesConst_VisitorThatIsNotReadShared_VisitorDataIsNotAvailable)
+    {
+        AzFramework::Spawnable::EntityAliasVisitor readWriteVisitor = m_spawnable->TryGetAliases();
+        ASSERT_TRUE(readWriteVisitor.IsValid());
+
+        AzFramework::Spawnable::EntityAliasConstVisitor visitor = m_spawnable->TryGetAliasesConst();
+        EXPECT_FALSE(visitor.IsValid());
+    }
+
+    TEST_F(SpawnableTest, TryGetAliasesConst_VisitorThatIsAlreadyReadShared_VisitorDataIsAvailable)
+    {
+        AzFramework::Spawnable::EntityAliasConstVisitor readVisitor = m_spawnable->TryGetAliasesConst();
+        ASSERT_TRUE(readVisitor.IsValid());
+
+        AzFramework::Spawnable::EntityAliasConstVisitor visitor = m_spawnable->TryGetAliasesConst();
+        EXPECT_TRUE(visitor.IsValid());
+    }
+
+
+    //
+    // TryGetAliases
+    //
+
+    TEST_F(SpawnableTest, TryGetAliases_GetVisitor_VisitorDataIsAvailable)
+    {
+        AzFramework::Spawnable::EntityAliasVisitor visitor = m_spawnable->TryGetAliases();
+        EXPECT_TRUE(visitor.IsValid());
+    }
+
+    TEST_F(SpawnableTest, TryGetAliasesConst_VisitorThatIsAlreadyShared_VisitorDataNotIsAvailable)
+    {
+        AzFramework::Spawnable::EntityAliasConstVisitor readVisitor = m_spawnable->TryGetAliasesConst();
+        ASSERT_TRUE(readVisitor.IsValid());
+
+        AzFramework::Spawnable::EntityAliasVisitor visitor = m_spawnable->TryGetAliases();
+        EXPECT_FALSE(visitor.IsValid());
+    }
+
+
+    //
+    // EntityAliasVisitor
+    //
+
+
+    //
+    // HasAliases
+    //
+
+    TEST_F(SpawnableTest, EntityAliasVisitor_HasAliases_EmptyAliasList_ReturnsFalse)
+    {
+        AzFramework::Spawnable::EntityAliasVisitor visitor = m_spawnable->TryGetAliases();
+        ASSERT_TRUE(visitor.IsValid());
+
+        EXPECT_FALSE(visitor.HasAliases());
+    }
+
+    TEST_F(SpawnableTest, EntityAliasVisitor_HasAliases_FilledInAliasList_ReturnsTrue)
+    {
+        InsertEntities(8);
+        InsertEntityAliases<8>();
+        AzFramework::Spawnable::EntityAliasVisitor visitor = m_spawnable->TryGetAliases();
+        ASSERT_TRUE(visitor.IsValid());
+
+        EXPECT_TRUE(visitor.HasAliases());
+    }
+
+
+    //
+    // Optimize
+    //
+
+    TEST_F(SpawnableTest, EntityAliasVisitor_Optimize_SortEntityAliases_AliasesAreSortedBySourceAndTargetId)
+    {
+        InsertEntities(DefaultEntityAliasTestCount);
+        InsertEntityAliases<DefaultEntityAliasTestCount>();
+        AzFramework::Spawnable::EntityAliasVisitor visitor = m_spawnable->TryGetAliases();
+        ASSERT_TRUE(visitor.IsValid());
+
+        // Optimize doesn't need to be explicitly called because the setup of the aliases will cause the alias list to be sorted and optimized.
+
+        uint32_t sourceIndex = 0;
+        uint32_t targetIndex = 0;
+        for (const AzFramework::Spawnable::EntityAlias& alias : visitor)
+        {
+            if (alias.m_sourceIndex != sourceIndex)
+            {
+                ASSERT_LE(sourceIndex, alias.m_sourceIndex);
+            }
+            else
+            {
+                ASSERT_LE(targetIndex, alias.m_targetIndex);
+            }
+            sourceIndex = alias.m_sourceIndex;
+            targetIndex = alias.m_targetIndex;
+        }
+    }
+
+    TEST_F(
+        SpawnableTest, EntityAliasVisitor_Optimize_RemoveUnused_OnlySecondToLastAliasRemains)
+    {
+        using namespace AzFramework;
+        InsertEntities(8);
+        InsertEntityAliases<8>(
+            { 0, 0, 0, 0, 0, 0, 0, 0 }, { 0, 1, 2, 3, 4, 5, 6, 7 },
+            { Spawnable::EntityAliasType::Replace, Spawnable::EntityAliasType::Original, Spawnable::EntityAliasType::Disable,
+              Spawnable::EntityAliasType::Replace, Spawnable::EntityAliasType::Original, Spawnable::EntityAliasType::Disable,
+              Spawnable::EntityAliasType::Replace, Spawnable::EntityAliasType::Original });
+
+        AzFramework::Spawnable::EntityAliasVisitor visitor = m_spawnable->TryGetAliases();
+        ASSERT_TRUE(visitor.IsValid());
+
+        EXPECT_EQ(1, AZStd::distance(visitor.begin(), visitor.end()));
+        EXPECT_EQ(Spawnable::EntityAliasType::Replace, visitor.begin()->m_aliasType);
+        EXPECT_EQ(6, visitor.begin()->m_targetIndex);
+    }
+
+    TEST_F(SpawnableTest, EntityAliasVisitor_Optimize_AddAdditional_ThreeAdditionalAliasesAreAdded)
+    {
+        using namespace AzFramework;
+        InsertEntities(8);
+        InsertEntityAliases<8>(
+            { 0, 0, 0, 0, 1, 2, 2, 2 }, { 0, 1, 2, 3, 4, 5, 6, 7 },
+            { Spawnable::EntityAliasType::Additional, Spawnable::EntityAliasType::Additional, Spawnable::EntityAliasType::Additional,
+              Spawnable::EntityAliasType::Additional, Spawnable::EntityAliasType::Additional, Spawnable::EntityAliasType::Additional,
+              Spawnable::EntityAliasType::Additional, Spawnable::EntityAliasType::Additional });
+
+        AzFramework::Spawnable::EntityAliasVisitor visitor = m_spawnable->TryGetAliases();
+        ASSERT_TRUE(visitor.IsValid());
+
+        EXPECT_EQ(11, AZStd::distance(visitor.begin(), visitor.end()));
+        EXPECT_EQ(Spawnable::EntityAliasType::Original, visitor.begin()->m_aliasType);
+        EXPECT_EQ(Spawnable::EntityAliasType::Original, visitor.begin()[5].m_aliasType);
+        EXPECT_EQ(Spawnable::EntityAliasType::Original, visitor.begin()[7].m_aliasType);
+    }
+
+    TEST_F(SpawnableTest, EntityAliasVisitor_Optimize_OriginalsOnly_AliasListIsEmpty)
+    {
+        using namespace AzFramework;
+        InsertEntities(8);
+        InsertEntityAliases<8>(
+            { 0, 0, 0, 0, 0, 0, 0, 0 }, { 0, 1, 2, 3, 4, 5, 6, 7 },
+            { Spawnable::EntityAliasType::Original, Spawnable::EntityAliasType::Original, Spawnable::EntityAliasType::Original,
+              Spawnable::EntityAliasType::Original, Spawnable::EntityAliasType::Original, Spawnable::EntityAliasType::Original,
+              Spawnable::EntityAliasType::Original, Spawnable::EntityAliasType::Original });
+
+        AzFramework::Spawnable::EntityAliasVisitor visitor = m_spawnable->TryGetAliases();
+        ASSERT_TRUE(visitor.IsValid());
+
+        EXPECT_EQ(0, AZStd::distance(visitor.begin(), visitor.end()));
+    }
+
+    TEST_F(SpawnableTest, EntityAliasVisitor_Optimize_MixedOriginals_AllOriginalsRemoved)
+    {
+        using namespace AzFramework;
+        InsertEntities(8);
+        InsertEntityAliases<8>(
+            { 0, 0, 0, 1, 1, 2, 2, 2 }, { 0, 1, 2, 3, 4, 5, 6, 7 },
+            { Spawnable::EntityAliasType::Original, Spawnable::EntityAliasType::Original, Spawnable::EntityAliasType::Original,
+              Spawnable::EntityAliasType::Original, Spawnable::EntityAliasType::Disable, Spawnable::EntityAliasType::Original,
+              Spawnable::EntityAliasType::Replace, Spawnable::EntityAliasType::Original });
+
+        AzFramework::Spawnable::EntityAliasVisitor visitor = m_spawnable->TryGetAliases();
+        ASSERT_TRUE(visitor.IsValid());
+
+        EXPECT_EQ(2, AZStd::distance(visitor.begin(), visitor.end()));
+        EXPECT_EQ(Spawnable::EntityAliasType::Disable, visitor.begin()->m_aliasType);
+        EXPECT_EQ(Spawnable::EntityAliasType::Replace, visitor.begin()[1].m_aliasType);
+    }
+
+    TEST_F(SpawnableTest, EntityAliasVisitor_Optimize_MergeAfterOriginal_NoAdditionalOriginalIsInserted)
+    {
+        using namespace AzFramework;
+        InsertEntities(8);
+        InsertEntityAliases<8>(
+            { 0, 0, 1, 1, 2, 2, 2, 2 }, { 0, 1, 2, 3, 4, 5, 6, 7 },
+            { Spawnable::EntityAliasType::Original, Spawnable::EntityAliasType::Merge, Spawnable::EntityAliasType::Replace,
+              Spawnable::EntityAliasType::Merge, Spawnable::EntityAliasType::Original, Spawnable::EntityAliasType::Original,
+              Spawnable::EntityAliasType::Original, Spawnable::EntityAliasType::Original });
+
+        AzFramework::Spawnable::EntityAliasVisitor visitor = m_spawnable->TryGetAliases();
+        ASSERT_TRUE(visitor.IsValid());
+
+        EXPECT_EQ(4, AZStd::distance(visitor.begin(), visitor.end()));
+        EXPECT_EQ(Spawnable::EntityAliasType::Original, visitor.begin()->m_aliasType);
+        EXPECT_EQ(Spawnable::EntityAliasType::Merge, visitor.begin()[1].m_aliasType);
+        EXPECT_EQ(Spawnable::EntityAliasType::Replace, visitor.begin()[2].m_aliasType);
+        EXPECT_EQ(Spawnable::EntityAliasType::Merge, visitor.begin()[3].m_aliasType);
+    }
+
+
+    //
+    // UpdateAliasType
+    //
+
+    TEST_F(SpawnableTest, EntityAliasVisitor_UpdateAliasType_AllToOriginal_NoAliasesAfterOptimization)
+    {
+        using namespace AzFramework;
+        InsertEntities(8);
+        InsertEntityAliases<8>(
+            { 0, 1, 2, 3, 4, 5, 6, 7 }, { 0, 1, 2, 3, 4, 5, 6, 7 },
+            { Spawnable::EntityAliasType::Replace, Spawnable::EntityAliasType::Replace, Spawnable::EntityAliasType::Replace,
+              Spawnable::EntityAliasType::Replace, Spawnable::EntityAliasType::Replace, Spawnable::EntityAliasType::Replace,
+              Spawnable::EntityAliasType::Replace, Spawnable::EntityAliasType::Replace });
+
+        AzFramework::Spawnable::EntityAliasVisitor visitor = m_spawnable->TryGetAliases();
+        ASSERT_TRUE(visitor.IsValid());
+
+        for (uint32_t i = 0; i < 8; ++i)
+        {
+            visitor.UpdateAliasType(i, Spawnable::EntityAliasType::Original);
+        }
+
+        for (const Spawnable::EntityAlias& alias : visitor)
+        {
+            EXPECT_EQ(Spawnable::EntityAliasType::Original, alias.m_aliasType);
+        }
+
+        visitor.Optimize();
+
+        EXPECT_EQ(0, AZStd::distance(visitor.begin(), visitor.end()));
+    }
+
+
+    //
+    // UpdateAliases
+    //
+
+    TEST_F(SpawnableTest, EntityAliasVisitor_UpdateAliases_AllToOriginal_NoAliasesAfterOptimization)
+    {
+        using namespace AzFramework;
+        InsertEntities(8);
+        InsertEntityAliases<8>(
+            { 0, 1, 2, 3, 4, 5, 6, 7 }, { 0, 1, 2, 3, 4, 5, 6, 7 },
+            { Spawnable::EntityAliasType::Replace, Spawnable::EntityAliasType::Replace, Spawnable::EntityAliasType::Replace,
+              Spawnable::EntityAliasType::Replace, Spawnable::EntityAliasType::Replace, Spawnable::EntityAliasType::Replace,
+              Spawnable::EntityAliasType::Replace, Spawnable::EntityAliasType::Replace });
+
+        AzFramework::Spawnable::EntityAliasVisitor visitor = m_spawnable->TryGetAliases();
+        ASSERT_TRUE(visitor.IsValid());
+
+        auto callback =
+            [](Spawnable::EntityAliasType& aliasType, bool& /*queueLoad*/, const AZ::Data::Asset<Spawnable>& /*aliasedSpawnable*/,
+               const AZ::Crc32 /*tag*/, const uint32_t /*sourceIndex*/, const uint32_t /*targetIndex*/)
+            {
+                aliasType = Spawnable::EntityAliasType::Original;
+            };
+        visitor.UpdateAliases(AZStd::move(callback));
+
+        for (const Spawnable::EntityAlias& alias : visitor)
+        {
+            EXPECT_EQ(Spawnable::EntityAliasType::Original, alias.m_aliasType);
+        }
+
+        visitor.Optimize();
+
+        EXPECT_EQ(0, AZStd::distance(visitor.begin(), visitor.end()));
+    }
+
+    TEST_F(SpawnableTest, EntityAliasVisitor_UpdateAliases_FilterByTag_OnlyOneAliasUpdated)
+    {
+        using namespace AzFramework;
+        InsertEntities(8);
+        InsertEntityAliases<8>(
+            { 0, 1, 2, 3, 4, 5, 6, 7 }, { 0, 1, 2, 3, 4, 5, 6, 7 },
+            { Spawnable::EntityAliasType::Replace, Spawnable::EntityAliasType::Replace, Spawnable::EntityAliasType::Replace,
+              Spawnable::EntityAliasType::Replace, Spawnable::EntityAliasType::Replace, Spawnable::EntityAliasType::Replace,
+              Spawnable::EntityAliasType::Replace, Spawnable::EntityAliasType::Replace });
+
+        AzFramework::Spawnable::EntityAliasVisitor visitor = m_spawnable->TryGetAliases();
+        ASSERT_TRUE(visitor.IsValid());
+
+        bool correctTag = false;
+        size_t numberOfUpdates = 0;
+        auto callback = [&correctTag, &numberOfUpdates](Spawnable::EntityAliasType& aliasType, bool& /*queueLoad*/,
+                           const AZ::Data::Asset<Spawnable>& /*aliasedSpawnable*/, const AZ::Crc32 tag, const uint32_t /*sourceIndex*/,
+                           const uint32_t /*targetIndex*/)
+        {
+            correctTag = (tag == AZ::Crc32(3));
+            numberOfUpdates++;
+            aliasType = Spawnable::EntityAliasType::Original;
+        };
+        visitor.UpdateAliases(AZ::Crc32(3), AZStd::move(callback));
+
+        EXPECT_EQ(Spawnable::EntityAliasType::Original, visitor.begin()[3].m_aliasType);
+    }
+
+
+    //
+    // AreAllSpawnablesReady
+    //
+
+    TEST_F(SpawnableTest, EntityAliasVisitor_AreAllSpawnablesReady_CheckFakeLoadedAssets_ReturnsTrue)
+    {
+        using namespace AzFramework;
+        InsertEntities(DefaultEntityAliasTestCount);
+        InsertEntityAliases<DefaultEntityAliasTestCount>();
+
+        AzFramework::Spawnable::EntityAliasVisitor visitor = m_spawnable->TryGetAliases();
+        ASSERT_TRUE(visitor.IsValid());
+
+        EXPECT_TRUE(visitor.AreAllSpawnablesReady());
+    }
+
+    TEST_F(SpawnableTest, EntityAliasVisitor_AreAllSpawnablesReady_CheckFakeNotLoadedAssets_ReturnsFalse)
+    {
+        using namespace AzFramework;
+        InsertEntities(8);
+        InsertEntityAliases<8>(true);
+
+        AzFramework::Spawnable::EntityAliasVisitor visitor = m_spawnable->TryGetAliases();
+        ASSERT_TRUE(visitor.IsValid());
+
+        EXPECT_FALSE(visitor.AreAllSpawnablesReady());
+    }
+
+
+    //
+    // ListTargetSpawnables
+    //
+
+    TEST_F(SpawnableTest, EntityAliasVisitor_ListTargetSpawnables_ListAllTargetAssets_AllTargetsListed)
+    {
+        using namespace AzFramework;
+        InsertEntities(DefaultEntityAliasTestCount);
+        InsertEntityAliases<DefaultEntityAliasTestCount>();
+
+        AzFramework::Spawnable::EntityAliasVisitor visitor = m_spawnable->TryGetAliases();
+        ASSERT_TRUE(visitor.IsValid());
+
+        size_t count = 0;
+        bool correctAssets = true;
+        auto callback = [&count, &correctAssets](const AZ::Data::Asset<Spawnable>& targetSpawnable)
+        {
+            correctAssets = correctAssets && (targetSpawnable.GetId().m_subId == count);
+            count++;
+        };
+        visitor.ListTargetSpawnables(callback);
+
+        EXPECT_EQ(8, count);
+        EXPECT_TRUE(correctAssets);
+    }
+
+    TEST_F(SpawnableTest, EntityAliasVisitor_ListTargetSpawnables_ListTaggedTargetAssets_OneAssetListed)
+    {
+        using namespace AzFramework;
+        InsertEntities(DefaultEntityAliasTestCount);
+        InsertEntityAliases<DefaultEntityAliasTestCount>();
+
+        AzFramework::Spawnable::EntityAliasVisitor visitor = m_spawnable->TryGetAliases();
+        ASSERT_TRUE(visitor.IsValid());
+
+        size_t count = 0;
+        bool correctAsset = false;
+        auto callback = [&count, &correctAsset](const AZ::Data::Asset<Spawnable>& targetSpawnable)
+        {
+            correctAsset = (targetSpawnable.GetId().m_subId == 3);
+            count++;
+        };
+        visitor.ListTargetSpawnables(AZ::Crc32(3), callback);
+
+        EXPECT_EQ(1, count);
+        EXPECT_TRUE(correctAsset);
+    }
+
+
+    //
+    // ListSpawnablesRequiringLoad
+    //
+
+    TEST_F(SpawnableTest, EntityAliasVisitor_ListSpawnablesRequiringLoad_AllSetToLoaded_AllTargetsListed)
+    {
+        using namespace AzFramework;
+        InsertEntities(DefaultEntityAliasTestCount);
+        InsertEntityAliases<DefaultEntityAliasTestCount>(true);
+
+        AzFramework::Spawnable::EntityAliasVisitor visitor = m_spawnable->TryGetAliases();
+        ASSERT_TRUE(visitor.IsValid());
+
+        size_t count = 0;
+        bool correctAssets = true;
+        auto callback = [&count, &correctAssets](const AZ::Data::Asset<Spawnable>& targetSpawnable)
+        {
+            correctAssets = correctAssets && (targetSpawnable.GetId().m_subId == count);
+            count++;
+        };
+        visitor.ListSpawnablesRequiringLoad(callback);
+
+        EXPECT_EQ(8, count);
+        EXPECT_TRUE(correctAssets);
+    }
+
+    TEST_F(SpawnableTest, EntityAliasVisitor_ListSpawnablesRequiringLoad_AllSetToNotLoaded_NoTargetsListed)
+    {
+        using namespace AzFramework;
+        InsertEntities(DefaultEntityAliasTestCount);
+        InsertEntityAliases<DefaultEntityAliasTestCount>(false);
+
+        AzFramework::Spawnable::EntityAliasVisitor visitor = m_spawnable->TryGetAliases();
+        ASSERT_TRUE(visitor.IsValid());
+
+        size_t count = 0;
+        auto callback = [&count](const AZ::Data::Asset<Spawnable>& /*targetSpawnable*/)
+        {
+            count++;
+        };
+        visitor.ListSpawnablesRequiringLoad(callback);
+
+        EXPECT_EQ(0, count);
+    }
+} // namespace UnitTest

Code/Framework/AzFramework/Tests/frameworktests_files.cmake

@@ -10,6 +10,7 @@ set(FILES
     Main.cpp
     Spawnable/SpawnableEntitiesInterfaceTests.cpp
     Spawnable/SpawnableEntitiesManagerTests.cpp
+    Spawnable/SpawnableTests.cpp
     ArchiveCompressionTests.cpp
     ArchiveTests.cpp
     BehaviorEntityTests.cpp

Code/Framework/AzQtComponents/AzQtComponents/Components/FancyDocking.cpp

@@ -2785,7 +2785,7 @@ namespace AzQtComponents
                     RepaintFloatingIndicators();
                 }
                 break;
-            case QEvent::WindowDeactivate:
+            case QEvent::WindowBlocked:
                 // If our main window is deactivated while we are in the middle of
                 // a docking drag operation (e.g. popup dialog for new level), we
                 // should cancel our drag operation because the mouse release event

Code/Framework/AzTest/AzTest/GemTestEnvironment.cpp

@@ -140,6 +140,11 @@ namespace AZ
 
         void GemTestEnvironment::TeardownEnvironment()
         {
+            for (AZ::ComponentDescriptor* descriptor : m_parameters->m_componentDescriptors)
+            {
+                m_application->UnregisterComponentDescriptor(descriptor);
+            }
+
             const AZ::Entity::ComponentArrayType& components = m_gemEntity->GetComponents();
             for (auto itComponent = components.rbegin(); itComponent != components.rend(); ++itComponent)
             {

Code/Framework/AzTest/AzTest/GemTestEnvironment.h

@@ -18,7 +18,7 @@ namespace AZ
 
         /// A test environment which is intended to facilitate writing unit tests which require components from a gem.
         class GemTestEnvironment
-            : public UnitTest::TraceBusHook
+            : public ::UnitTest::TraceBusHook
         {
         public:
             GemTestEnvironment();

Code/Framework/AzToolsFramework/AzToolsFramework/AssetBrowser/AssetBrowserTableModel.h

@@ -40,9 +40,9 @@ namespace AzToolsFramework
             QVariant data(const QModelIndex& index, int role = Qt::DisplayRole) const override;
             QModelIndex parent(const QModelIndex& child) const override;
             QModelIndex sibling(int row, int column, const QModelIndex& idx) const override;
+            int rowCount(const QModelIndex& parent = QModelIndex()) const override;
 
         protected:
-            int rowCount(const QModelIndex& parent = QModelIndex()) const override;
             QVariant headerData(int section, Qt::Orientation orientation, int role /* = Qt::DisplayRole */) const override;
             ////////////////////////////////////////////////////////////////////
 
@@ -55,7 +55,7 @@ namespace AzToolsFramework
         private slots:
             void SourceDataChanged(const QModelIndex& topLeft, const QModelIndex& bottomRight);
         private:
-            AZ::u64 m_numberOfItemsDisplayed = 0;
+            AZ::u64 m_numberOfItemsDisplayed = 50;
             int m_displayedItemsCounter = 0;
             QPointer<AssetBrowserFilterModel> m_filterModel;
             QMap<int, QModelIndex> m_indexMap;

Code/Framework/AzToolsFramework/AzToolsFramework/Entity/PrefabEditorEntityOwnershipService.cpp

@@ -581,15 +581,15 @@ namespace AzToolsFramework
     {
         if (m_rootInstance && m_playInEditorData.m_isEnabled)
         {
-            AZ_Assert(m_playInEditorData.m_entities.IsSet(),
+            AZ_Assert(
+                m_playInEditorData.m_entities.IsSet(),
                 "Invalid Game Mode Entities Container encountered after play-in-editor stopped. "
                 "Confirm that the container was initialized correctly");
 
             m_playInEditorData.m_entities.DespawnAllEntities();
             m_playInEditorData.m_entities.Alert(
                 [assets = AZStd::move(m_playInEditorData.m_assets),
-                 deactivatedEntities = AZStd::move(m_playInEditorData.m_deactivatedEntities)]
-                ([[maybe_unused]]uint32_t generation) mutable
+                 deactivatedEntities = AZStd::move(m_playInEditorData.m_deactivatedEntities)]([[maybe_unused]] uint32_t generation) mutable
                 {
                     auto end = deactivatedEntities.rend();
                     for (auto it = deactivatedEntities.rbegin(); it != end; ++it)
@@ -614,15 +614,15 @@ namespace AzToolsFramework
                     AzFramework::GameEntityContextEventBus::Broadcast(&AzFramework::GameEntityContextEventBus::Events::OnGameEntitiesReset);
                 });
             m_playInEditorData.m_entities.Clear();
-        }
 
-        // Game entity cleanup is queued onto the next tick via the DespawnEntities call.
-        // To avoid both game entities and Editor entities active at the same time
-        // we flush the tick queue to ensure the game entities are cleared first.
-        // The Alert callback that follows the DespawnEntities call will then reactivate the editor entities
-        // This should be considered temporary as a move to a less rigid event sequence that supports async entity clean up
-        // is the desired direction forward.
-        AZ::TickBus::ExecuteQueuedEvents();
+            // Game entity cleanup is queued onto the next tick via the DespawnEntities call.
+            // To avoid both game entities and Editor entities active at the same time
+            // we flush the tick queue to ensure the game entities are cleared first.
+            // The Alert callback that follows the DespawnEntities call will then reactivate the editor entities
+            // This should be considered temporary as a move to a less rigid event sequence that supports async entity clean up
+            // is the desired direction forward.
+            AZ::TickBus::ExecuteQueuedEvents();
+        }
 
         m_playInEditorData.m_isEnabled = false;
     }

Code/Framework/AzToolsFramework/AzToolsFramework/Prefab/Instance/Instance.cpp

@@ -129,7 +129,7 @@ namespace AzToolsFramework
 
         void Instance::SetLinkId(LinkId linkId)
         {
-            m_linkId = AZStd::move(linkId);
+            m_linkId = linkId;
         }
 
         LinkId Instance::GetLinkId() const
@@ -154,23 +154,26 @@ namespace AzToolsFramework
 
         bool Instance::AddEntity(AZ::Entity& entity)
         {
-            EntityAlias newEntityAlias = GenerateEntityAlias();
-            return AddEntity(entity, newEntityAlias);
+            return AddEntity(entity, GenerateEntityAlias());
+        }
+
+        bool Instance::AddEntity(AZStd::unique_ptr<AZ::Entity>&& entity)
+        {
+            return AddEntity(AZStd::move(entity), GenerateEntityAlias());
         }
 
         bool Instance::AddEntity(AZ::Entity& entity, EntityAlias entityAlias)
         {
-            if (!RegisterEntity(entity.GetId(), entityAlias))
-            {
-                return false;
-            }
+            return
+                RegisterEntity(entity.GetId(), entityAlias) && 
+                m_entities.emplace(AZStd::move(entityAlias), &entity).second;
+        }
 
-            if (!m_entities.emplace(AZStd::make_pair(entityAlias, &entity)).second)
-            {
-                return false;
-            }
-
-            return true;
+        bool Instance::AddEntity(AZStd::unique_ptr<AZ::Entity>&& entity, EntityAlias entityAlias)
+        {
+            return
+                RegisterEntity(entity->GetId(), entityAlias) &&
+                m_entities.emplace(AZStd::move(entityAlias), AZStd::move(entity)).second;
         }
 
         AZStd::unique_ptr<AZ::Entity> Instance::DetachEntity(const AZ::EntityId& entityId)
@@ -228,6 +231,23 @@ namespace AzToolsFramework
             m_entities.clear();
         }
 
+        AZStd::unique_ptr<AZ::Entity> Instance::ReplaceEntity(AZStd::unique_ptr<AZ::Entity>&& entity, EntityAliasView alias)
+        {
+            AZStd::unique_ptr<AZ::Entity> result;
+            auto it = m_entities.find(alias);
+            if (it != m_entities.end())
+            {
+                // Swap entity ids as these need to remain stable
+                AZ::EntityId originalId = it->second->GetId();
+                it->second->SetId(entity->GetId());
+                entity->SetId(originalId);
+
+                result = AZStd::move(it->second);
+                it->second = AZStd::move(entity);
+            }
+            return result;
+        }
+
         void Instance::RemoveNestedEntities(
             const AZStd::function<bool(const AZStd::unique_ptr<AZ::Entity>&)>& filter)
         {
@@ -377,7 +397,12 @@ namespace AzToolsFramework
             return entityAliases;
         }
 
-        void Instance::GetNestedEntityIds(const AZStd::function<bool(AZ::EntityId)>& callback)
+        size_t Instance::GetEntityAliasCount() const
+        {
+            return m_entities.size();
+        }
+
+        void Instance::GetNestedEntityIds(const AZStd::function<bool(AZ::EntityId)>& callback) const
         {
             GetEntityIds(callback);
 
@@ -387,7 +412,7 @@ namespace AzToolsFramework
             }
         }
 
-        void Instance::GetEntityIds(const AZStd::function<bool(AZ::EntityId)>& callback)
+        void Instance::GetEntityIds(const AZStd::function<bool(AZ::EntityId)>& callback) const
         {
             for (auto&&[entityAlias, entityId] : m_templateToInstanceEntityIdMap)
             {
@@ -398,6 +423,17 @@ namespace AzToolsFramework
             }
         }
 
+        void Instance::GetEntityIdToAlias(const AZStd::function<bool(AZ::EntityId, EntityAliasView)>& callback) const
+        {
+            for (auto&& [entityAlias, entityId] : m_templateToInstanceEntityIdMap)
+            {
+                if (!callback(entityId, entityAlias))
+                {
+                    break;
+                }
+            }
+        }
+
         bool Instance::GetEntities_Impl(const AZStd::function<bool(AZStd::unique_ptr<AZ::Entity>&)>& callback)
         {
             for (auto& [entityAlias, entity] : m_entities)
@@ -514,24 +550,81 @@ namespace AzToolsFramework
             }
         }
 
-        EntityAliasOptionalReference Instance::GetEntityAlias(const AZ::EntityId& id)
+        EntityAliasOptionalReference Instance::GetEntityAlias(AZ::EntityId id)
         {
-            if (m_instanceToTemplateEntityIdMap.count(id))
-            {
-                return m_instanceToTemplateEntityIdMap[id];
-            }
-                
-            return AZStd::nullopt;
+            auto it = m_instanceToTemplateEntityIdMap.find(id);
+            return it != m_instanceToTemplateEntityIdMap.end() ? EntityAliasOptionalReference(it->second)
+                                                               : EntityAliasOptionalReference(AZStd::nullopt);
         }
 
-        AZ::EntityId Instance::GetEntityId(const EntityAlias& alias)
+        EntityAliasView Instance::GetEntityAlias(AZ::EntityId id) const
         {
-            if (m_templateToInstanceEntityIdMap.count(alias))
+            auto it = m_instanceToTemplateEntityIdMap.find(id);
+            return it != m_instanceToTemplateEntityIdMap.end() ? EntityAliasView(it->second) : EntityAliasView();
+        }
+
+        AZStd::pair<Instance*, EntityAliasView> Instance::FindInstanceAndAlias(AZ::EntityId entity)
+        {
+            auto it = m_instanceToTemplateEntityIdMap.find(entity);
+            if (it != m_instanceToTemplateEntityIdMap.end())
             {
-                return m_templateToInstanceEntityIdMap[alias];
+                return AZStd::pair<Instance*, EntityAliasView>(this, it->second);
             }
-                
-            return AZ::EntityId();
+            else
+            {
+                for (auto&& [_, instance] : m_nestedInstances)
+                {
+                    AZStd::pair<Instance*, EntityAliasView> next = instance->FindInstanceAndAlias(entity);
+                    if (next.first != nullptr)
+                    {
+                        return next;
+                    }
+                }
+            }
+            return AZStd::pair<Instance*, EntityAliasView>(nullptr, "");
+        }
+
+        AZStd::pair<const Instance*, EntityAliasView> Instance::FindInstanceAndAlias(AZ::EntityId entity) const
+        {
+            return const_cast<Instance*>(this)->FindInstanceAndAlias(entity);
+        }
+
+        EntityOptionalReference Instance::GetEntity(const EntityAlias& alias)
+        {
+            auto it = m_entities.find(alias);
+            return it != m_entities.end() ? EntityOptionalReference(*it->second) : EntityOptionalReference(AZStd::nullopt);
+        }
+
+        EntityOptionalConstReference Instance::GetEntity(const EntityAlias& alias) const
+        {
+            auto it = m_entities.find(alias);
+            return it != m_entities.end() ? EntityOptionalConstReference(*it->second) : EntityOptionalConstReference(AZStd::nullopt);
+        }
+
+        AZ::EntityId Instance::GetEntityId(const EntityAlias& alias) const
+        {
+            auto it = m_templateToInstanceEntityIdMap.find(alias);
+            return it != m_templateToInstanceEntityIdMap.end() ? it->second : AZ::EntityId();
+        }
+
+        AZ::EntityId Instance::GetEntityIdFromAliasPath(AliasPathView relativeAliasPath) const
+        {
+            const Instance* instance = this;
+            AliasPathView path = relativeAliasPath.ParentPath();
+            for (auto it : path)
+            {
+                InstanceOptionalConstReference child = instance->FindNestedInstance(it.Native());
+                if (child.has_value())
+                {
+                    instance = &(child->get());
+                }
+                else
+                {
+                    return AZ::EntityId();
+                }
+            }
+
+            return instance->GetEntityId(relativeAliasPath.Filename().Native());
         }
 
         AZStd::vector<InstanceAlias> Instance::GetNestedInstanceAliases(TemplateId templateId) const
@@ -572,6 +665,32 @@ namespace AzToolsFramework
             return aliasPathResult;
         }
 
+        AliasPath Instance::GetAliasPathRelativeToInstance(const AZ::EntityId& entity) const
+        {
+            AliasPath result = AliasPath(s_aliasPathSeparator);
+            auto&& [instance, alias] = FindInstanceAndAlias(entity);
+            if (instance)
+            {
+                AZStd::vector<const Instance*> instanceChain;
+                
+                while (instance && instance != this)
+                {
+                    instanceChain.push_back(instance);
+                    instance = instance->m_parent;
+                }
+
+                for (auto it = instanceChain.rbegin(); it != instanceChain.rend(); ++it)
+                {
+                    result.Append((*it)->m_alias);
+                }
+                return result.Append(alias);
+            }
+            else
+            {
+                return result;
+            }
+        }
+
         EntityAlias Instance::GenerateEntityAlias()
         {
             return AZStd::string::format("Entity_%s", AZ::Entity::MakeId().ToString().c_str());

Code/Framework/AzToolsFramework/AzToolsFramework/Prefab/Instance/Instance.h

@@ -38,6 +38,7 @@ namespace AzToolsFramework
         using AliasPath = AZ::IO::Path;
         using AliasPathView = AZ::IO::PathView;
         using EntityAlias = AZStd::string;
+        using EntityAliasView = AZStd::string_view;
         using InstanceAlias = AZStd::string;
 
         class Instance;
@@ -83,9 +84,17 @@ namespace AzToolsFramework
             void SetContainerEntityName(AZStd::string_view containerName);
 
             bool AddEntity(AZ::Entity& entity);
+            bool AddEntity(AZStd::unique_ptr<AZ::Entity>&& entity);
             bool AddEntity(AZ::Entity& entity, EntityAlias entityAlias);
+            bool AddEntity(AZStd::unique_ptr<AZ::Entity>&& entity, EntityAlias entityAlias);
             AZStd::unique_ptr<AZ::Entity> DetachEntity(const AZ::EntityId& entityId);
             void DetachEntities(const AZStd::function<void(AZStd::unique_ptr<AZ::Entity>)>& callback);
+            /**
+             * Replaces the entity stored under the provided alias with a new one.
+             *
+             * @return The original entity or a nullptr if not found.
+             */
+            AZStd::unique_ptr<AZ::Entity> ReplaceEntity(AZStd::unique_ptr<AZ::Entity>&& entity, EntityAliasView alias);
 
             /**
             * Detaches all entities in the instance hierarchy.
@@ -109,13 +118,15 @@ namespace AzToolsFramework
             * @return The list of EntityAliases
             */
             AZStd::vector<EntityAlias> GetEntityAliases();
+            size_t GetEntityAliasCount() const;
 
             /**
             * Gets the ids for the entities in the Instance DOM.  Can recursively trace all nested instances.
             */
-            void GetNestedEntityIds(const AZStd::function<bool(AZ::EntityId)>& callback);
+            void GetNestedEntityIds(const AZStd::function<bool(AZ::EntityId)>& callback) const;
 
-            void GetEntityIds(const AZStd::function<bool(AZ::EntityId)>& callback);
+            void GetEntityIds(const AZStd::function<bool(AZ::EntityId)>& callback) const;
+            void GetEntityIdToAlias(const AZStd::function<bool(AZ::EntityId, EntityAliasView)>& callback) const;
 
             /**
             * Gets the entities in the Instance DOM.  Can recursively trace all nested instances.
@@ -131,14 +142,33 @@ namespace AzToolsFramework
             *
             * @return entityAlias via optional
             */
-            AZStd::optional<AZStd::reference_wrapper<EntityAlias>> GetEntityAlias(const AZ::EntityId& id);
+            EntityAliasOptionalReference GetEntityAlias(AZ::EntityId id);
+            EntityAliasView GetEntityAlias(AZ::EntityId id) const;
+            /**
+             * Searches for the entity in this instance and its nested instances.
+             *
+             * @return The instance that owns the entity and the alias under which the entity is known.
+             *      If the entity isn't found then the instance will be null and the alias empty.
+             */
+            AZStd::pair<Instance*, EntityAliasView> FindInstanceAndAlias(AZ::EntityId entity);
+            AZStd::pair<const Instance*, EntityAliasView> FindInstanceAndAlias(AZ::EntityId entity) const;
+
+            EntityOptionalReference GetEntity(const EntityAlias& alias);
+            EntityOptionalConstReference GetEntity(const EntityAlias& alias) const;
 
             /**
             * Gets the id for a given EnitityAlias in the Instance DOM.
             *
             * @return entityId, invalid ID if not found
             */
-            AZ::EntityId GetEntityId(const EntityAlias& alias);
+            AZ::EntityId GetEntityId(const EntityAlias& alias) const;
+
+            /**
+            * Retrieves the entity id from an alias path that's relative to this instance.
+            * 
+            * @return entityId, invalid ID if not found
+            */
+            AZ::EntityId GetEntityIdFromAliasPath(AliasPathView relativeAliasPath) const;
 
 
             /**
@@ -180,6 +210,7 @@ namespace AzToolsFramework
 
             static EntityAlias GenerateEntityAlias();
             AliasPath GetAbsoluteInstanceAliasPath() const;
+            AliasPath GetAliasPathRelativeToInstance(const AZ::EntityId& entity) const;
 
             static InstanceAlias GenerateInstanceAlias();
 

Code/Framework/AzToolsFramework/AzToolsFramework/Prefab/Instance/InstanceToTemplateInterface.h

@@ -49,7 +49,7 @@ namespace AzToolsFramework
             //! @param instanceToExclude An optional reference to an instance of the template being updated that should not be refreshes as part of propagation.
             //!     Defaults to nullopt, which means that all instances will be refreshed.
             //! @return True if the template was patched correctly, false if the operation failed.
-            virtual bool PatchTemplate(PrefabDomValue& providedPatch, TemplateId templateId, InstanceOptionalReference instanceToExclude = AZStd::nullopt) = 0;
+            virtual bool PatchTemplate(PrefabDomValue& providedPatch, TemplateId templateId, InstanceOptionalConstReference instanceToExclude = AZStd::nullopt) = 0;
 
             virtual void ApplyPatchesToInstance(const AZ::EntityId& entityId, PrefabDom& patches, const Instance& instanceToAddPatches) = 0;
 

Code/Framework/AzToolsFramework/AzToolsFramework/Prefab/Instance/InstanceToTemplatePropagator.cpp

@@ -156,7 +156,7 @@ namespace AzToolsFramework
             }
         }
 
-        bool InstanceToTemplatePropagator::PatchTemplate(PrefabDomValue& providedPatch, TemplateId templateId, InstanceOptionalReference instanceToExclude)
+        bool InstanceToTemplatePropagator::PatchTemplate(PrefabDomValue& providedPatch, TemplateId templateId, InstanceOptionalConstReference instanceToExclude)
         {
             PrefabDom& templateDomReference = m_prefabSystemComponentInterface->FindTemplateDom(templateId);
 

Code/Framework/AzToolsFramework/AzToolsFramework/Prefab/Instance/InstanceToTemplatePropagator.h

@@ -33,7 +33,7 @@ namespace AzToolsFramework
 
             InstanceOptionalReference GetTopMostInstanceInHierarchy(AZ::EntityId entityId) override;
 
-            bool PatchTemplate(PrefabDomValue& providedPatch, TemplateId templateId, InstanceOptionalReference instanceToExclude = AZStd::nullopt) override;
+            bool PatchTemplate(PrefabDomValue& providedPatch, TemplateId templateId, InstanceOptionalConstReference instanceToExclude = AZStd::nullopt) override;
 
             void ApplyPatchesToInstance(const AZ::EntityId& entityId, PrefabDom& patches, const Instance& instanceToAddPatches) override;
 

Code/Framework/AzToolsFramework/AzToolsFramework/Prefab/Instance/InstanceUpdateExecutor.cpp

@@ -52,7 +52,7 @@ namespace AzToolsFramework
             AZ::Interface<InstanceUpdateExecutorInterface>::Unregister(this);
         }
 
-        void InstanceUpdateExecutor::AddTemplateInstancesToQueue(TemplateId instanceTemplateId, InstanceOptionalReference instanceToExclude)
+        void InstanceUpdateExecutor::AddTemplateInstancesToQueue(TemplateId instanceTemplateId, InstanceOptionalConstReference instanceToExclude)
         {
             auto findInstancesResult =
                 m_templateInstanceMapperInterface->FindInstancesOwnedByTemplate(instanceTemplateId);
@@ -66,7 +66,7 @@ namespace AzToolsFramework
                 return;
             }
 
-            Instance* instanceToExcludePtr = nullptr;
+            const Instance* instanceToExcludePtr = nullptr;
             if (instanceToExclude.has_value())
             {
                 instanceToExcludePtr = &(instanceToExclude->get());

Code/Framework/AzToolsFramework/AzToolsFramework/Prefab/Instance/InstanceUpdateExecutor.h

@@ -31,7 +31,7 @@ namespace AzToolsFramework
 
             explicit InstanceUpdateExecutor(int instanceCountToUpdateInBatch = 0);
 
-            void AddTemplateInstancesToQueue(TemplateId instanceTemplateId, InstanceOptionalReference instanceToExclude = AZStd::nullopt) override;
+            void AddTemplateInstancesToQueue(TemplateId instanceTemplateId, InstanceOptionalConstReference instanceToExclude = AZStd::nullopt) override;
             bool UpdateTemplateInstancesInQueue() override;
             virtual void RemoveTemplateInstanceFromQueue(const Instance* instance) override;
 

Code/Framework/AzToolsFramework/AzToolsFramework/Prefab/Instance/InstanceUpdateExecutorInterface.h

@@ -23,7 +23,7 @@ namespace AzToolsFramework
             virtual ~InstanceUpdateExecutorInterface() = default;
 
             // Add all Instances of Template with given Id into a queue for updating them later.
-            virtual void AddTemplateInstancesToQueue(TemplateId instanceTemplateId, InstanceOptionalReference instanceToExclude = AZStd::nullopt) = 0;
+            virtual void AddTemplateInstancesToQueue(TemplateId instanceTemplateId, InstanceOptionalConstReference instanceToExclude = AZStd::nullopt) = 0;
 
             // Update Instances in the waiting queue.
             virtual bool UpdateTemplateInstancesInQueue() = 0;

Code/Framework/AzToolsFramework/AzToolsFramework/Prefab/PrefabPublicHandler.cpp

@@ -777,7 +777,7 @@ namespace AzToolsFramework
             linkUpdate->SetParent(undoBatch);
             linkUpdate->Capture(patch, linkId);
 
-            linkUpdate->Redo(parentInstance);
+            linkUpdate->Redo(parentInstance->get());
         }
 
         void PrefabPublicHandler::Internal_HandleEntityChange(
@@ -788,8 +788,7 @@ namespace AzToolsFramework
             PrefabUndoEntityUpdate* state = aznew PrefabUndoEntityUpdate(AZStd::to_string(static_cast<AZ::u64>(entityId)));
             state->SetParent(undoBatch);
             state->Capture(beforeState, afterState, entityId);
-
-            state->Redo(instance);
+            state->Redo(instance->get());
         }
 
         void PrefabPublicHandler::Internal_HandleInstanceChange(
@@ -1167,6 +1166,60 @@ namespace AzToolsFramework
 
             ScopedUndoBatch undoBatch("Delete Selected");
 
+            AZ_PROFILE_SCOPE(AzToolsFramework, "Internal::DeleteEntities:UndoCaptureAndPurgeEntities");
+
+            Prefab::PrefabDom instanceDomBefore;
+            m_instanceToTemplateInterface->GenerateDomForInstance(instanceDomBefore, commonOwningInstance->get());
+
+            if (deleteDescendants)
+            {
+                AZStd::vector<AZ::Entity*> entities;
+                AZStd::vector<Instance*> instances;
+
+                PrefabOperationResult retrieveEntitiesAndInstancesOutcome =
+                    RetrieveAndSortPrefabEntitiesAndInstances(inputEntityList, commonOwningInstance->get(), entities, instances);
+
+                if (!retrieveEntitiesAndInstancesOutcome.IsSuccess())
+                {
+                    return AZStd::move(retrieveEntitiesAndInstancesOutcome);
+                }
+
+                for (AZ::Entity* entity : entities)
+                {
+                    commonOwningInstance->get().DetachEntity(entity->GetId()).release();
+                    AZ::ComponentApplicationBus::Broadcast(&AZ::ComponentApplicationRequests::DeleteEntity, entity->GetId());
+                }
+
+                for (auto& nestedInstance : instances)
+                {
+                    AZStd::unique_ptr<Instance> outInstance =
+                        commonOwningInstance->get().DetachNestedInstance(nestedInstance->GetInstanceAlias());
+                    RemoveLink(outInstance, commonOwningInstance->get().GetTemplateId(), undoBatch.GetUndoBatch());
+                    outInstance.reset();
+                }
+            }
+            else
+            {
+                for (AZ::EntityId entityId : entityIdsNoFocusContainer)
+                {
+                    InstanceOptionalReference owningInstance = m_instanceEntityMapperInterface->FindOwningInstance(entityId);
+                    // If this is the container entity, it actually represents the instance so get its owner
+                    if (owningInstance->get().GetContainerEntityId() == entityId)
+                    {
+                        auto instancePtr = commonOwningInstance->get().DetachNestedInstance(owningInstance->get().GetInstanceAlias());
+                        RemoveLink(instancePtr, commonOwningInstance->get().GetTemplateId(), undoBatch.GetUndoBatch());
+                    }
+                    else
+                    {
+                        commonOwningInstance->get().DetachEntity(entityId);
+                        AZ::ComponentApplicationBus::Broadcast(&AZ::ComponentApplicationRequests::DeleteEntity, entityId);
+                    }
+                }
+            }
+
+            Prefab::PrefabDom instanceDomAfter;
+            m_instanceToTemplateInterface->GenerateDomForInstance(instanceDomAfter, commonOwningInstance->get());
+
             // In order to undo DeleteSelected, we have to create a selection command which selects the current selection
             // and then add the deletion as children.
             // Commands always execute themselves first and then their children (when going forwards)
@@ -1174,81 +1227,22 @@ namespace AzToolsFramework
             EntityIdList selectedEntities;
             ToolsApplicationRequestBus::BroadcastResult(selectedEntities, &ToolsApplicationRequests::GetSelectedEntities);
             SelectionCommand* selCommand = aznew SelectionCommand(selectedEntities, "Delete Entities");
+            selCommand->SetParent(undoBatch.GetUndoBatch());
+            AZ_PROFILE_SCOPE(AzToolsFramework, "Internal::DeleteEntities:RunRedo");
+            selCommand->RunRedo();
 
             // We insert a "deselect all" command before we delete the entities. This ensures the delete operations aren't changing
             // selection state, which triggers expensive UI updates. By deselecting up front, we are able to do those expensive
             // UI updates once at the start instead of once for each entity.
-            {
-                EntityIdList deselection;
-                SelectionCommand* deselectAllCommand = aznew SelectionCommand(deselection, "Deselect Entities");
-                deselectAllCommand->SetParent(selCommand);
-            }
-
-            {
-                AZ_PROFILE_SCOPE(AzToolsFramework, "Internal::DeleteEntities:UndoCaptureAndPurgeEntities");
-
-                Prefab::PrefabDom instanceDomBefore;
-                m_instanceToTemplateInterface->GenerateDomForInstance(instanceDomBefore, commonOwningInstance->get());
-
-                if (deleteDescendants)
-                {
-                    AZStd::vector<AZ::Entity*> entities;
-                    AZStd::vector<Instance*> instances;
-
-                    PrefabOperationResult retrieveEntitiesAndInstancesOutcome =
-                        RetrieveAndSortPrefabEntitiesAndInstances(inputEntityList, commonOwningInstance->get(), entities, instances);
-
-                    if (!retrieveEntitiesAndInstancesOutcome.IsSuccess())
-                    {
-                        return AZStd::move(retrieveEntitiesAndInstancesOutcome);
-                    }
-
-                    for (AZ::Entity* entity : entities)
-                    {
-                        commonOwningInstance->get().DetachEntity(entity->GetId()).release();
-                        AZ::ComponentApplicationBus::Broadcast(&AZ::ComponentApplicationRequests::DeleteEntity, entity->GetId());
-                    }
-
-                    for (auto& nestedInstance : instances)
-                    {
-                        AZStd::unique_ptr<Instance> outInstance = commonOwningInstance->get().DetachNestedInstance(nestedInstance->GetInstanceAlias());
-                        RemoveLink(outInstance, commonOwningInstance->get().GetTemplateId(), undoBatch.GetUndoBatch());
-                        outInstance.reset();
-                    }
-                }
-                else
-                {
-                    for (AZ::EntityId entityId : entityIdsNoFocusContainer)
-                    {
-                        InstanceOptionalReference owningInstance = m_instanceEntityMapperInterface->FindOwningInstance(entityId);
-                        // If this is the container entity, it actually represents the instance so get its owner
-                        if (owningInstance->get().GetContainerEntityId() == entityId)
-                        {
-                            auto instancePtr = commonOwningInstance->get().DetachNestedInstance(owningInstance->get().GetInstanceAlias());
-                            RemoveLink(instancePtr, commonOwningInstance->get().GetTemplateId(), undoBatch.GetUndoBatch());
-                        }
-                        else
-                        {
-                            commonOwningInstance->get().DetachEntity(entityId);
-                            AZ::ComponentApplicationBus::Broadcast(&AZ::ComponentApplicationRequests::DeleteEntity, entityId);
-                        }
-                    }
-                }
-
-                Prefab::PrefabDom instanceDomAfter;
-                m_instanceToTemplateInterface->GenerateDomForInstance(instanceDomAfter, commonOwningInstance->get());
-
-                PrefabUndoInstance* command = aznew PrefabUndoInstance("Instance deletion");
-                command->Capture(instanceDomBefore, instanceDomAfter, commonOwningInstance->get().GetTemplateId());
-                command->SetParent(selCommand);
-            }
-
-            selCommand->SetParent(undoBatch.GetUndoBatch());
-            {
-                AZ_PROFILE_SCOPE(AzToolsFramework, "Internal::DeleteEntities:RunRedo");
-                selCommand->RunRedo();
-            }
+            EntityIdList deselection;
+            SelectionCommand* deselectAllCommand = aznew SelectionCommand(deselection, "Deselect Entities");
+            deselectAllCommand->SetParent(undoBatch.GetUndoBatch());
 
+            PrefabUndoInstance* command = aznew PrefabUndoInstance("Instance deletion");
+            command->Capture(instanceDomBefore, instanceDomAfter, commonOwningInstance->get().GetTemplateId());
+            command->SetParent(undoBatch.GetUndoBatch());
+            command->Redo(commonOwningInstance->get());
+            
             return AZ::Success();
         }
 
@@ -1338,7 +1332,7 @@ namespace AzToolsFramework
                     command->SetParent(undoBatch.GetUndoBatch());
                     {
                         AZ_PROFILE_SCOPE(AzToolsFramework, "Internal::DetachPrefab:RunRedo");
-                        command->RunRedo();
+                        command->Redo(parentInstance);
                     }
 
                     instancePtr->DetachNestedInstances(

Code/Framework/AzToolsFramework/AzToolsFramework/Prefab/PrefabSystemComponent.cpp

@@ -159,11 +159,9 @@ namespace AzToolsFramework
                 newInstance->SetTemplateId(newTemplateId);
             }
         }
-
-        void PrefabSystemComponent::PropagateTemplateChanges(TemplateId templateId, InstanceOptionalReference instanceToExclude)
+        
+        void PrefabSystemComponent::PropagateTemplateChanges(TemplateId templateId, InstanceOptionalConstReference instanceToExclude)
         {
-            UpdatePrefabInstances(templateId, instanceToExclude);
-
             auto templateIdToLinkIdsIterator = m_templateToLinkIdsMap.find(templateId);
             if (templateIdToLinkIdsIterator != m_templateToLinkIdsMap.end())
             {
@@ -174,6 +172,7 @@ namespace AzToolsFramework
                     templateIdToLinkIdsIterator->second.end()));
                 UpdateLinkedInstances(linkIdsToUpdateQueue);
             }
+            UpdatePrefabInstances(templateId, instanceToExclude);
         }
 
         void PrefabSystemComponent::UpdatePrefabTemplate(TemplateId templateId, const PrefabDom& updatedDom)
@@ -191,7 +190,7 @@ namespace AzToolsFramework
             }
         }
 
-        void PrefabSystemComponent::UpdatePrefabInstances(TemplateId templateId, InstanceOptionalReference instanceToExclude)
+        void PrefabSystemComponent::UpdatePrefabInstances(TemplateId templateId, InstanceOptionalConstReference instanceToExclude)
         {
             m_instanceUpdateExecutor.AddTemplateInstancesToQueue(templateId, instanceToExclude);
         }

Code/Framework/AzToolsFramework/AzToolsFramework/Prefab/PrefabSystemComponent.h

@@ -231,7 +231,7 @@ namespace AzToolsFramework
              */
             void UpdatePrefabTemplate(TemplateId templateId, const PrefabDom& updatedDom) override;
 
-            void PropagateTemplateChanges(TemplateId templateId, InstanceOptionalReference instanceToExclude = AZStd::nullopt) override;
+            void PropagateTemplateChanges(TemplateId templateId, InstanceOptionalConstReference instanceToExclude = AZStd::nullopt) override;
 
             /**
              * Updates all Instances owned by a Template.
@@ -240,7 +240,7 @@ namespace AzToolsFramework
              * @param instanceToExclude An optional reference to an instance of the template being updated that should not be refreshed
              *        as part of propagation.Defaults to nullopt, which means that all instances will be refreshed.
              */
-            void UpdatePrefabInstances(TemplateId templateId, InstanceOptionalReference instanceToExclude = AZStd::nullopt);
+            void UpdatePrefabInstances(TemplateId templateId, InstanceOptionalConstReference instanceToExclude = AZStd::nullopt);
 
         private:
             AZ_DISABLE_COPY_MOVE(PrefabSystemComponent);

Code/Framework/AzToolsFramework/AzToolsFramework/Prefab/PrefabSystemComponentInterface.h

@@ -67,7 +67,7 @@ namespace AzToolsFramework
 
             virtual PrefabDom& FindTemplateDom(TemplateId templateId) = 0;
             virtual void UpdatePrefabTemplate(TemplateId templateId, const PrefabDom& updatedDom) = 0;
-            virtual void PropagateTemplateChanges(TemplateId templateId, InstanceOptionalReference instanceToExclude = AZStd::nullopt) = 0;
+            virtual void PropagateTemplateChanges(TemplateId templateId, InstanceOptionalConstReference instanceToExclude = AZStd::nullopt) = 0;
 
             virtual AZStd::unique_ptr<Instance> InstantiatePrefab(
                 AZ::IO::PathView filePath, InstanceOptionalReference parent = AZStd::nullopt) = 0;

Code/Framework/AzToolsFramework/AzToolsFramework/Prefab/PrefabUndo.cpp

@@ -51,6 +51,10 @@ namespace AzToolsFramework
             m_instanceToTemplateInterface->PatchTemplate(m_redoPatch, m_templateId);
         }
 
+        void PrefabUndoInstance::Redo(InstanceOptionalConstReference instance)
+        {
+            m_instanceToTemplateInterface->PatchTemplate(m_redoPatch, m_templateId, instance);
+        }
 
         //PrefabEntityUpdateUndo
         PrefabUndoEntityUpdate::PrefabUndoEntityUpdate(const AZStd::string& undoOperationName)
@@ -110,10 +114,10 @@ namespace AzToolsFramework
                 m_templateId);
         }
 
-        void PrefabUndoEntityUpdate::Redo(InstanceOptionalReference instanceToExclude)
+        void PrefabUndoEntityUpdate::Redo(InstanceOptionalConstReference instance)
         {
             [[maybe_unused]] bool isPatchApplicationSuccessful =
-                m_instanceToTemplateInterface->PatchTemplate(m_redoPatch, m_templateId, instanceToExclude);
+                m_instanceToTemplateInterface->PatchTemplate(m_redoPatch, m_templateId, instance);
 
             AZ_Error(
                 "Prefab", isPatchApplicationSuccessful,
@@ -310,12 +314,12 @@ namespace AzToolsFramework
             UpdateLink(m_linkDomNext);
         }
 
-        void PrefabUndoLinkUpdate::Redo(InstanceOptionalReference instanceToExclude)
+        void PrefabUndoLinkUpdate::Redo(InstanceOptionalConstReference instanceToExclude)
         {
             UpdateLink(m_linkDomNext, instanceToExclude);
         }
 
-        void PrefabUndoLinkUpdate::UpdateLink(PrefabDom& linkDom, InstanceOptionalReference instanceToExclude)
+        void PrefabUndoLinkUpdate::UpdateLink(PrefabDom& linkDom, InstanceOptionalConstReference instanceToExclude)
         {
             LinkReference link = m_prefabSystemComponentInterface->FindLink(m_linkId);
 

Code/Framework/AzToolsFramework/AzToolsFramework/Prefab/PrefabUndo.h

@@ -53,6 +53,7 @@ namespace AzToolsFramework
 
             void Undo() override;
             void Redo() override;
+            void Redo(InstanceOptionalConstReference instance);
         };
 
         //! handles entity updates, such as when the values on an entity change
@@ -72,7 +73,7 @@ namespace AzToolsFramework
             void Undo() override;
             void Redo() override;
             //! Overload to allow to apply the change, but prevent instanceToExclude from being refreshed.
-            void Redo(InstanceOptionalReference instanceToExclude);
+            void Redo(InstanceOptionalConstReference instanceToExclude);
 
         private:
             InstanceEntityMapperInterface* m_instanceEntityMapperInterface = nullptr;
@@ -137,10 +138,10 @@ namespace AzToolsFramework
             void Undo() override;
             void Redo() override;
             //! Overload to allow to apply the change, but prevent instanceToExclude from being refreshed.
-            void Redo(InstanceOptionalReference instanceToExclude);
+            void Redo(InstanceOptionalConstReference instanceToExclude);
 
         private:
-            void UpdateLink(PrefabDom& linkDom, InstanceOptionalReference instanceToExclude = AZStd::nullopt);
+            void UpdateLink(PrefabDom& linkDom, InstanceOptionalConstReference instanceToExclude = AZStd::nullopt);
 
             LinkId m_linkId;
             PrefabDom m_linkDomNext;  //data for delete/update

Code/Framework/AzToolsFramework/AzToolsFramework/Prefab/PrefabUndoHelpers.cpp

@@ -26,7 +26,7 @@ namespace AzToolsFramework
                 PrefabUndoInstance* state = aznew Prefab::PrefabUndoInstance(undoMessage);
                 state->Capture(instanceDomBeforeUpdate, instanceDomAfterUpdate, instance.GetTemplateId());
                 state->SetParent(undoBatch);
-                state->Redo();
+                state->Redo(instance);
             }
 
             LinkId CreateLink(

Code/Framework/AzToolsFramework/AzToolsFramework/Prefab/Spawnable/PrefabCatchmentProcessor.cpp

@@ -13,9 +13,12 @@
 #include <AzCore/Serialization/Utils.h>
 #include <AzFramework/Spawnable/Spawnable.h>
 #include <AzToolsFramework/Entity/EditorEntityHelpers.h>
+#include <AzToolsFramework/Prefab/Instance/Instance.h>
+#include <AzToolsFramework/Prefab/PrefabDomUtils.h>
 #include <AzToolsFramework/Prefab/Spawnable/PrefabCatchmentProcessor.h>
 #include <AzToolsFramework/Prefab/Spawnable/SpawnableUtils.h>
 
+
 namespace AzToolsFramework::Prefab::PrefabConversionUtils
 {
     void PrefabCatchmentProcessor::Process(PrefabProcessorContext& context)
@@ -37,7 +40,7 @@ namespace AzToolsFramework::Prefab::PrefabConversionUtils
                 ->Value("Text", SerializationFormats::Text);
 
             serializeContext->Class<PrefabCatchmentProcessor, PrefabProcessor>()
-                ->Version(2)
+                ->Version(3)
                 ->Field("SerializationFormat", &PrefabCatchmentProcessor::m_serializationFormat);
         }
     }
@@ -45,6 +48,8 @@ namespace AzToolsFramework::Prefab::PrefabConversionUtils
     void PrefabCatchmentProcessor::ProcessPrefab(PrefabProcessorContext& context, AZStd::string_view prefabName, PrefabDom& prefab,
         AZ::DataStream::StreamType serializationFormat)
     {
+        using namespace AzToolsFramework::Prefab::SpawnableUtils;
+
         AZStd::string uniqueName = prefabName;
         uniqueName += AzFramework::Spawnable::DotFileExtension;
 
@@ -59,33 +64,38 @@ namespace AzToolsFramework::Prefab::PrefabConversionUtils
             AZStd::move(uniqueName), context.GetSourceUuid(), AZStd::move(serializer));
         AZ_Assert(spawnable, "Failed to create a new spawnable.");
 
-        bool result = SpawnableUtils::CreateSpawnable(*spawnable, prefab, object.GetReferencedAssets());
-        if (result)
+        Instance instance;
+        if (Prefab::PrefabDomUtils::LoadInstanceFromPrefabDom(
+                instance, prefab, object.GetReferencedAssets(),
+                Prefab::PrefabDomUtils::LoadFlags::AssignRandomEntityId)) // Always assign random entity ids because the spawnable is
+                                                                          // going to be used to create clones of the entities.
         {
+            // Resolve entity aliases that store PrefabDOM information to use the spawnable instead. This is done before the entities are
+            // moved from the instance as they'd otherwise can't be found.
+            context.ResolveSpawnableEntityAliases(prefabName, *spawnable, instance);
+
             AzFramework::Spawnable::EntityList& entities = spawnable->GetEntities();
-            for (auto it = entities.begin(); it != entities.end(); )
-            {
-                if (*it)
+            instance.DetachAllEntitiesInHierarchy(
+                [&entities, &context](AZStd::unique_ptr<AZ::Entity> entity)
                 {
-                    (*it)->InvalidateDependencies();
-                    AZ::Entity::DependencySortOutcome evaluation = (*it)->EvaluateDependenciesGetDetails();
-                    if (evaluation.IsSuccess())
+                    if (entity)
                     {
-                        ++it;
+                        entity->InvalidateDependencies();
+                        AZ::Entity::DependencySortOutcome evaluation = entity->EvaluateDependenciesGetDetails();
+                        if (evaluation.IsSuccess())
+                        {
+                            entities.emplace_back(AZStd::move(entity));
+                        }
+                        else
+                        {
+                            AZ_Error(
+                                "Prefabs", false, "Entity '%s' %s cannot be activated for the following reason: %s",
+                                entity->GetName().c_str(), entity->GetId().ToString().c_str(), evaluation.GetError().m_message.c_str());
+                            context.ErrorEncountered();
+                        }
                     }
-                    else
-                    {
-                        AZ_Error(
-                            "Prefabs", false, "Entity '%s' %s cannot be activated for the following reason: %s", (*it)->GetName().c_str(),
-                            (*it)->GetId().ToString().c_str(), evaluation.GetError().m_message.c_str());
-                        it = entities.erase(it);
-                    }
-                }
-                else
-                {
-                    it = entities.erase(it);
-                }
-            }
+                });
+
             SpawnableUtils::SortEntitiesByTransformHierarchy(*spawnable);
             context.GetProcessedObjects().push_back(AZStd::move(object));
         }

Code/Framework/AzToolsFramework/AzToolsFramework/Prefab/Spawnable/PrefabConversionPipeline.cpp

@@ -54,6 +54,7 @@ namespace AzToolsFramework::Prefab::PrefabConversionUtils
         {
             processor->Process(context);
         }
+        context.ResolveLinks();
     }
     size_t PrefabConversionPipeline::CalculateProcessorFingerprint(AZ::SerializeContext* context)
     {

Code/Framework/AzToolsFramework/AzToolsFramework/Prefab/Spawnable/PrefabProcessorContext.cpp

@@ -6,12 +6,26 @@
  *
  */
 
+#include <AzCore/Interface/Interface.h>
 #include <AzFramework/Spawnable/Spawnable.h>
-
+#include <AzToolsFramework/Prefab/Instance/InstanceEntityMapperInterface.h>
 #include <AzToolsFramework/Prefab/Spawnable/PrefabProcessorContext.h>
+#include <AzToolsFramework/Prefab/Spawnable/SpawnableUtils.h>
 
 namespace AzToolsFramework::Prefab::PrefabConversionUtils
 {
+    EntityAliasSpawnableLink::EntityAliasSpawnableLink(AzFramework::Spawnable& spawnable, AZ::EntityId index)
+        : m_spawnable(spawnable)
+        , m_index(index)
+    {
+    }
+
+    EntityAliasPrefabLink::EntityAliasPrefabLink(AZStd::string prefabName, AzToolsFramework::Prefab::AliasPath alias)
+        : m_prefabName(AZStd::move(prefabName))
+        , m_alias(AZStd::move(alias))
+    {
+    }
+
     PrefabProcessorContext::PrefabProcessorContext(const AZ::Uuid& sourceUuid)
         : m_sourceUuid(sourceUuid)
     {}
@@ -45,7 +59,8 @@ namespace AzToolsFramework::Prefab::PrefabConversionUtils
         return !m_prefabs.empty();
     }
 
-    bool PrefabProcessorContext::RegisterSpawnableProductAssetDependency(AZStd::string prefabName, AZStd::string dependentPrefabName)
+    bool PrefabProcessorContext::RegisterSpawnableProductAssetDependency(
+        AZStd::string prefabName, AZStd::string dependentPrefabName, EntityAliasSpawnableLoadBehavior loadBehavior)
     {
         using ConversionUtils = PrefabConversionUtils::ProcessedObjectStore;
 
@@ -55,10 +70,11 @@ namespace AzToolsFramework::Prefab::PrefabConversionUtils
         dependentPrefabName += AzFramework::Spawnable::DotFileExtension;
         uint32_t spawnablePrefabSubId = ConversionUtils::BuildSubId(AZStd::move(dependentPrefabName));
 
-        return RegisterSpawnableProductAssetDependency(spawnableSubId, spawnablePrefabSubId);
+        return RegisterSpawnableProductAssetDependency(spawnableSubId, spawnablePrefabSubId, loadBehavior);
     }
 
-    bool PrefabProcessorContext::RegisterSpawnableProductAssetDependency(AZStd::string prefabName, const AZ::Data::AssetId& dependentAssetId)
+    bool PrefabProcessorContext::RegisterSpawnableProductAssetDependency(
+        AZStd::string prefabName, const AZ::Data::AssetId& dependentAssetId, EntityAliasSpawnableLoadBehavior loadBehavior)
     {
         using ConversionUtils = PrefabConversionUtils::ProcessedObjectStore;
 
@@ -67,20 +83,78 @@ namespace AzToolsFramework::Prefab::PrefabConversionUtils
 
         AZ::Data::AssetId spawnableAssetId(GetSourceUuid(), spawnableSubId);
 
-        return RegisterProductAssetDependency(spawnableAssetId, dependentAssetId);
+        return RegisterProductAssetDependency(spawnableAssetId, dependentAssetId, ToAssetLoadBehavior(loadBehavior));
     }
 
-    bool PrefabProcessorContext::RegisterSpawnableProductAssetDependency(uint32_t spawnableAssetSubId, uint32_t dependentSpawnableAssetSubId)
+    bool PrefabProcessorContext::RegisterSpawnableProductAssetDependency(
+        uint32_t spawnableAssetSubId, uint32_t dependentSpawnableAssetSubId, EntityAliasSpawnableLoadBehavior loadBehavior)
     {
         AZ::Data::AssetId spawnableAssetId(GetSourceUuid(), spawnableAssetSubId);
         AZ::Data::AssetId dependentSpawnableAssetId(GetSourceUuid(), dependentSpawnableAssetSubId);
 
-        return RegisterProductAssetDependency(spawnableAssetId, dependentSpawnableAssetId);
+        return RegisterProductAssetDependency(spawnableAssetId, dependentSpawnableAssetId, ToAssetLoadBehavior(loadBehavior));
     }
 
     bool PrefabProcessorContext::RegisterProductAssetDependency(const AZ::Data::AssetId& assetId, const AZ::Data::AssetId& dependentAssetId)
     {
-        return m_registeredProductAssetDependencies[assetId].emplace(dependentAssetId).second;
+        return RegisterProductAssetDependency(assetId, dependentAssetId, AZ::Data::AssetLoadBehavior::NoLoad);
+    }
+
+    bool PrefabProcessorContext::RegisterProductAssetDependency(
+        const AZ::Data::AssetId& assetId, const AZ::Data::AssetId& dependentAssetId, AZ::Data::AssetLoadBehavior loadBehavior)
+    {
+        auto dependencies = m_registeredProductAssetDependencies.equal_range(assetId);
+        if (dependencies.first != dependencies.second)
+        {
+            for (auto it = dependencies.first; it != dependencies.second; ++it)
+            {
+                if (it->second.m_assetId == dependentAssetId)
+                {
+                    if (it->second.m_loadBehavior < loadBehavior)
+                    {
+                        it->second.m_loadBehavior = loadBehavior;
+                    }
+                    return true;
+                }
+            }
+        }
+
+        return m_registeredProductAssetDependencies.emplace(assetId, AssetDependencyInfo{ dependentAssetId, loadBehavior }).second;
+    }
+
+    void PrefabProcessorContext::RegisterSpawnableEntityAlias(EntityAliasStore link)
+    {
+        m_entityAliases.push_back(AZStd::move(link));
+    }
+
+    void PrefabProcessorContext::ResolveSpawnableEntityAliases(
+        AZStd::string_view prefabName, AzFramework::Spawnable& spawnable, const AzToolsFramework::Prefab::Instance& instance)
+    {
+        using namespace AzToolsFramework::Prefab;
+
+        for (EntityAliasStore& entityAlias : m_entityAliases)
+        {
+            auto sourcePrefab = AZStd::get_if<EntityAliasPrefabLink>(&entityAlias.m_source);
+            if (sourcePrefab != nullptr && sourcePrefab->m_prefabName == prefabName)
+            {
+                AZ::EntityId id = instance.GetEntityIdFromAliasPath(sourcePrefab->m_alias);
+                AZ_Assert(
+                    id.IsValid(),
+                    "Entity '%s' was not found in Prefab Instance created from '%s' even though it was previously found.",
+                    sourcePrefab->m_alias.c_str(), sourcePrefab->m_prefabName.c_str());
+                entityAlias.m_source.emplace<EntityAliasSpawnableLink>(spawnable, id);
+            }
+
+            auto targetPrefab = AZStd::get_if<EntityAliasPrefabLink>(&entityAlias.m_target);
+            if (targetPrefab != nullptr && targetPrefab->m_prefabName == prefabName)
+            {
+                AZ::EntityId id = instance.GetEntityIdFromAliasPath(targetPrefab->m_alias);
+                AZ_Assert(
+                    id.IsValid(), "Entity '%s' was not found in Prefab Instance created from '%s' even though it was previously found.",
+                    targetPrefab->m_alias.c_str(), targetPrefab->m_prefabName.c_str());
+                entityAlias.m_target.emplace<EntityAliasSpawnableLink>(spawnable, id);
+            }
+        }
     }
 
     PrefabProcessorContext::ProcessedObjectStoreContainer& PrefabProcessorContext::GetProcessedObjects()
@@ -118,6 +192,46 @@ namespace AzToolsFramework::Prefab::PrefabConversionUtils
         return m_sourceUuid;
     }
 
+    void PrefabProcessorContext::ResolveLinks()
+    {
+        // Store the aliases visitor here when first encountered to avoid the visitor sorting the aliases for every addition.
+        // Once this map goes out of scope the visitors will be destroyed and in turn sort their aliases.
+        AZStd::unordered_map<AZ::Data::AssetId, AzFramework::Spawnable::EntityAliasVisitor> aliasVisitors;
+
+        for (EntityAliasStore& alias : m_entityAliases)
+        {
+            auto source = AZStd::get_if<EntityAliasSpawnableLink>(&alias.m_source);
+            AZ_Assert(source, "Entity alias found that has a source that's not yet resolved to a spawnable");
+            auto target = AZStd::get_if<EntityAliasSpawnableLink>(&alias.m_target);
+            AZ_Assert(target, "Entity alias found that has a target that's not yet resolved to a spawnable");
+
+            uint32_t sourceIndex = SpawnableUtils::FindEntityIndex(source->m_index, source->m_spawnable);
+            AZ_Assert(
+                sourceIndex != SpawnableUtils::InvalidEntityIndex, "Entity %zu not found in source spawnable while resolving to index.",
+                aznumeric_cast<AZ::u64>(source->m_index));
+            uint32_t targetIndex = SpawnableUtils::FindEntityIndex(target->m_index, target->m_spawnable);
+            AZ_Assert(
+                targetIndex != SpawnableUtils::InvalidEntityIndex, "Entity %zu not found in target spawnable while resolving to index.",
+                aznumeric_cast<AZ::u64>(target->m_index));
+
+            AZ::Data::AssetLoadBehavior loadBehavior = ToAssetLoadBehavior(alias.m_loadBehavior);
+
+            auto it = aliasVisitors.find(source->m_spawnable.GetId());
+            if (it == aliasVisitors.end())
+            {
+                AzFramework::Spawnable::EntityAliasVisitor visitor = source->m_spawnable.TryGetAliases();
+                AZ_Assert(visitor.IsValid(), "Unable to obtain lock for a newly create spawnable.");
+                it = aliasVisitors.emplace(source->m_spawnable.GetId(), AZStd::move(visitor)).first;
+            }
+            it->second.AddAlias(
+                AZ::Data::Asset<AzFramework::Spawnable>(&target->m_spawnable, loadBehavior), alias.m_tag, sourceIndex, targetIndex,
+                alias.m_aliasType, alias.m_loadBehavior == EntityAliasSpawnableLoadBehavior::QueueLoad);
+
+            // Register the dependency between the two spawnables.
+            RegisterProductAssetDependency(source->m_spawnable.GetId(), target->m_spawnable.GetId(), loadBehavior);
+        }
+    }
+
     bool PrefabProcessorContext::HasCompletedSuccessfully() const
     {
         return m_completedSuccessfully;
@@ -127,4 +241,10 @@ namespace AzToolsFramework::Prefab::PrefabConversionUtils
     {
         m_completedSuccessfully = false;
     }
+
+    AZ::Data::AssetLoadBehavior PrefabProcessorContext::ToAssetLoadBehavior(EntityAliasSpawnableLoadBehavior loadBehavior) const
+    {
+        return loadBehavior == EntityAliasSpawnableLoadBehavior::DependentLoad ? AZ::Data::AssetLoadBehavior::PreLoad
+                                                                               : AZ::Data::AssetLoadBehavior::NoLoad;
+    }
 } // namespace AzToolsFramework::Prefab::PrefabConversionUtils

Code/Framework/AzToolsFramework/AzToolsFramework/Prefab/Spawnable/PrefabProcessorContext.h

@@ -9,24 +9,83 @@
 #pragma once
 
 #include <AzCore/Component/ComponentExport.h>
+#include <AzCore/IO/Path/Path.h>
 #include <AzCore/Memory/SystemAllocator.h>
 #include <AzCore/Serialization/Json/JsonSerialization.h>
 #include <AzCore/std/containers/unordered_map.h>
+#include <AzCore/std/containers/variant.h>
 #include <AzCore/std/containers/vector.h>
 #include <AzCore/std/functional.h>
 #include <AzCore/std/string/string.h>
 #include <AzCore/std/string/string_view.h>
+#include <AzFramework/Spawnable/Spawnable.h>
+#include <AzToolsFramework/Prefab/Instance/Instance.h>
 #include <AzToolsFramework/Prefab/PrefabDomTypes.h>
 #include <AzToolsFramework/Prefab/Spawnable/ProcesedObjectStore.h>
 
 namespace AzToolsFramework::Prefab::PrefabConversionUtils
 {
+    enum class EntityAliasType : uint8_t
+    {
+        Disable,         //!< No alias is added.
+        OptionalReplace, //!< At runtime the entity might be replaced. If the alias is disabled the original entity will be spawned.
+                         //!<   The original entity will be left in the spawnable and a copy is returned.
+        Replace,         //!< At runtime the entity will be replaced. If the alias is disabled nothing will be spawned. The original
+                         //!<   entity is returned and a blank entity is left.
+        Additional,      //!< At runtime the alias entity will be added as an additional but unrelated entity with a new entity id.
+                         //!<   An empty entity will be returned.
+        Merge            //!< At runtime the components in both entities will be merged. An empty entity will be returned. The added
+                         //!<   components may no conflict with the entities already in the root entity.
+    };
+
+    enum class EntityAliasSpawnableLoadBehavior : uint8_t
+    {
+        NoLoad,         //!< Don't load the spawnable referenced in the entity alias. Loading will be up to the caller.
+        QueueLoad,      //!< Queue the spawnable referenced in the entity alias for loading. This will be an async load because asset
+                        //!<    handlers aren't allowed to start a blocking load as this can lead to deadlocks. This option will allow
+                        //!<    to disable loading the referenced spawnable through the event fired from the spawnables asset handler.
+        DependentLoad   //!< The spawnable referenced in the entity alias is made a dependency of the spawnable that holds the entity
+                        //!<    alias. This will cause the spawnable to be automatically loaded along with the owning spawnable.
+    };
+
+    struct EntityAliasSpawnableLink
+    {
+        EntityAliasSpawnableLink(AzFramework::Spawnable& spawnable, AZ::EntityId index);
+
+        AzFramework::Spawnable& m_spawnable;
+        AZ::EntityId m_index;
+    };
+
+    struct EntityAliasPrefabLink
+    {
+        EntityAliasPrefabLink(AZStd::string prefabName, AzToolsFramework::Prefab::AliasPath alias);
+
+        AZStd::string m_prefabName;
+        AzToolsFramework::Prefab::AliasPath m_alias;
+    };
+
+    struct EntityAliasStore
+    {
+        using LinkStore = AZStd::variant<AZStd::monostate, EntityAliasSpawnableLink, EntityAliasPrefabLink>;
+
+        LinkStore m_source;
+        LinkStore m_target;
+        uint32_t m_tag;
+        AzFramework::Spawnable::EntityAliasType m_aliasType;
+        EntityAliasSpawnableLoadBehavior m_loadBehavior;
+    };
+
+    struct AssetDependencyInfo
+    {
+        AZ::Data::AssetId m_assetId;
+        AZ::Data::AssetLoadBehavior m_loadBehavior;
+    };
+
     class PrefabProcessorContext
     {
     public:
         using ProcessedObjectStoreContainer = AZStd::vector<ProcessedObjectStore>;
-        using ProductAssetDependencyContainer =
-            AZStd::unordered_map<AZ::Data::AssetId, AZStd::unordered_set<AZ::Data::AssetId>>;
+        using ProductAssetDependencyContainer = AZStd::unordered_multimap<AZ::Data::AssetId, AssetDependencyInfo>;
 
         AZ_CLASS_ALLOCATOR(PrefabProcessorContext, AZ::SystemAllocator, 0);
         AZ_RTTI(PrefabProcessorContext, "{C7D77E3A-C544-486B-B774-7C82C38FE22F}");
@@ -39,11 +98,20 @@ namespace AzToolsFramework::Prefab::PrefabConversionUtils
         virtual void ListPrefabs(const AZStd::function<void(AZStd::string_view, const PrefabDom&)>& callback) const;
         virtual bool HasPrefabs() const;
 
-        virtual bool RegisterSpawnableProductAssetDependency(AZStd::string prefabName, AZStd::string dependentPrefabName);
-        virtual bool RegisterSpawnableProductAssetDependency(AZStd::string prefabName, const AZ::Data::AssetId& dependentAssetId);
-        virtual bool RegisterSpawnableProductAssetDependency(uint32_t spawnableAssetSubId, uint32_t dependentSpawnableAssetSubId);
+        virtual bool RegisterSpawnableProductAssetDependency(
+            AZStd::string prefabName, AZStd::string dependentPrefabName, EntityAliasSpawnableLoadBehavior loadBehavior);
+        virtual bool RegisterSpawnableProductAssetDependency(
+            AZStd::string prefabName, const AZ::Data::AssetId& dependentAssetId, EntityAliasSpawnableLoadBehavior loadBehavior);
+        virtual bool RegisterSpawnableProductAssetDependency(
+            uint32_t spawnableAssetSubId, uint32_t dependentSpawnableAssetSubId, EntityAliasSpawnableLoadBehavior loadBehavior);
         virtual bool RegisterProductAssetDependency(const AZ::Data::AssetId& assetId, const AZ::Data::AssetId& dependentAssetId);
+        virtual bool RegisterProductAssetDependency(
+            const AZ::Data::AssetId& assetId, const AZ::Data::AssetId& dependentAssetId, AZ::Data::AssetLoadBehavior loadBehavior);
 
+        virtual void RegisterSpawnableEntityAlias(EntityAliasStore link);
+        virtual void ResolveSpawnableEntityAliases(
+            AZStd::string_view prefabName, AzFramework::Spawnable& spawnable, const AzToolsFramework::Prefab::Instance& instance);
+        
         virtual ProcessedObjectStoreContainer& GetProcessedObjects();
         virtual const ProcessedObjectStoreContainer& GetProcessedObjects() const;
 
@@ -54,13 +122,19 @@ namespace AzToolsFramework::Prefab::PrefabConversionUtils
         virtual const AZ::PlatformTagSet& GetPlatformTags() const;
         virtual const AZ::Uuid& GetSourceUuid() const;
 
+        virtual void ResolveLinks();
+
         virtual bool HasCompletedSuccessfully() const;
         virtual void ErrorEncountered();
 
     protected:
         using NamedPrefabContainer = AZStd::unordered_map<AZStd::string, PrefabDom>;
+        using SpawnableEntityAliasStore = AZStd::vector<EntityAliasStore>;
+
+        AZ::Data::AssetLoadBehavior ToAssetLoadBehavior(EntityAliasSpawnableLoadBehavior loadBehavior) const;
 
         NamedPrefabContainer m_prefabs;
+        SpawnableEntityAliasStore m_entityAliases;
         ProcessedObjectStoreContainer m_products;
         ProductAssetDependencyContainer m_registeredProductAssetDependencies;
 

Code/Framework/AzToolsFramework/AzToolsFramework/Prefab/Spawnable/ProcesedObjectStore.cpp

@@ -11,7 +11,16 @@
 
 namespace AzToolsFramework::Prefab::PrefabConversionUtils
 {
-    ProcessedObjectStore::ProcessedObjectStore(AZStd::string uniqueId, AZStd::unique_ptr<AZ::Data::AssetData> asset, SerializerFunction assetSerializer)
+    void ProcessedObjectStore::AssetSmartPtrDeleter::operator()(AZ::Data::AssetData* asset)
+    {
+        if (asset->GetUseCount() == 0)
+        {
+            // Only delete the asset if it wasn't turned into a full asset
+            delete asset;
+        }
+    }
+
+    ProcessedObjectStore::ProcessedObjectStore(AZStd::string uniqueId, AssetSmartPtr asset, SerializerFunction assetSerializer)
         : m_uniqueId(AZStd::move(uniqueId))
         , m_assetSerializer(AZStd::move(assetSerializer))
         , m_asset(AZStd::move(asset))
@@ -62,7 +71,7 @@ namespace AzToolsFramework::Prefab::PrefabConversionUtils
         return m_referencedAssets;
     }
 
-    AZStd::unique_ptr<AZ::Data::AssetData> ProcessedObjectStore::ReleaseAsset()
+    auto ProcessedObjectStore::ReleaseAsset() -> AssetSmartPtr
     {
         return AZStd::move(m_asset);
     }
@@ -72,6 +81,11 @@ namespace AzToolsFramework::Prefab::PrefabConversionUtils
         return AzFramework::SpawnableAssetHandler::BuildSubId(id);
     }
 
+    uint32_t ProcessedObjectStore::GetSubId() const
+    {
+        return m_asset->GetId().m_subId;
+    }
+
     const AZStd::string& ProcessedObjectStore::GetId() const
     {
         return m_uniqueId;

Code/Framework/AzToolsFramework/AzToolsFramework/Prefab/Spawnable/ProcesedObjectStore.h

@@ -26,6 +26,12 @@ namespace AzToolsFramework::Prefab::PrefabConversionUtils
     public:
         using SerializerFunction = AZStd::function<bool(AZStd::vector<uint8_t>&, const ProcessedObjectStore&)>;
 
+        struct AssetSmartPtrDeleter
+        {
+            void operator()(AZ::Data::AssetData* asset);
+        };
+        using AssetSmartPtr = AZStd::unique_ptr<AZ::Data::AssetData, AssetSmartPtrDeleter>; 
+
         //! Constructs a new instance.
         //! @param uniqueId A name for the object that's unique within the scope of the Prefab. This name will be used to generate a sub id for the product
         //!     which requires that the name to be stable between runs.
@@ -37,24 +43,24 @@ namespace AzToolsFramework::Prefab::PrefabConversionUtils
         
         bool Serialize(AZStd::vector<uint8_t>& output) const;
         static uint32_t BuildSubId(AZStd::string_view id);
+        uint32_t GetSubId() const;
 
         bool HasAsset() const;
         const AZ::Data::AssetType& GetAssetType() const;
         const AZ::Data::AssetData& GetAsset() const;
         AZ::Data::AssetData& GetAsset();
-        AZStd::unique_ptr<AZ::Data::AssetData> ReleaseAsset();
+        AssetSmartPtr ReleaseAsset();
 
         AZStd::vector<AZ::Data::Asset<AZ::Data::AssetData>>& GetReferencedAssets();
         const AZStd::vector<AZ::Data::Asset<AZ::Data::AssetData>>& GetReferencedAssets() const;
 
-
         const AZStd::string& GetId() const;
 
     private:
-        ProcessedObjectStore(AZStd::string uniqueId, AZStd::unique_ptr<AZ::Data::AssetData> asset, SerializerFunction assetSerializer);
+        ProcessedObjectStore(AZStd::string uniqueId, AssetSmartPtr asset, SerializerFunction assetSerializer);
 
         SerializerFunction m_assetSerializer;
-        AZStd::unique_ptr<AZ::Data::AssetData> m_asset;
+        AssetSmartPtr m_asset;
         AZStd::vector<AZ::Data::Asset<AZ::Data::AssetData>> m_referencedAssets;
         AZStd::string m_uniqueId;
     };
@@ -66,7 +72,7 @@ namespace AzToolsFramework::Prefab::PrefabConversionUtils
         static_assert(AZStd::is_base_of_v<AZ::Data::AssetData, T>,
             "ProcessedObjectStore can only be created from a class that derives from AZ::Data::AssetData.");
         AZ::Data::AssetId assetId(sourceId, BuildSubId(uniqueId));
-        auto instance = AZStd::make_unique<T>(assetId, AZ::Data::AssetData::AssetStatus::Ready);
+        auto instance = AssetSmartPtr(aznew T(assetId, AZ::Data::AssetData::AssetStatus::Ready));
         ProcessedObjectStore resultLeft(AZStd::move(uniqueId), AZStd::move(instance), AZStd::move(assetSerializer));
         T* resultRight = static_cast<T*>(&resultLeft.GetAsset());
         return AZStd::make_pair<ProcessedObjectStore, T*>(AZStd::move(resultLeft), resultRight);

Code/Framework/AzToolsFramework/AzToolsFramework/Prefab/Spawnable/SpawnableUtils.cpp

@@ -8,9 +8,12 @@
 
 #include <AzToolsFramework/Prefab/Spawnable/SpawnableUtils.h>
 
+#include <AzCore/Casting/numeric_cast.h>
+#include <AzCore/Component/ComponentApplicationBus.h>
 #include <AzCore/Component/Entity.h>
 #include <AzCore/Component/EntityUtils.h>
 #include <AzCore/Component/TransformBus.h>
+#include <AzCore/Serialization/SerializeContext.h>
 #include <AzCore/std/algorithm.h>
 #include <AzCore/std/smart_ptr/unique_ptr.h>
 #include <AzFramework/Spawnable/Spawnable.h>
@@ -20,18 +23,134 @@
 
 namespace AzToolsFramework::Prefab::SpawnableUtils
 {
+    namespace Internal
+    {
+        AZ::SerializeContext* GetSerializeContext()
+        {
+            AZ::SerializeContext* result = nullptr;
+            AZ::ComponentApplicationBus::BroadcastResult(result, &AZ::ComponentApplicationBus::Events::GetSerializeContext);
+            AZ_Assert(result, "SpawnbleUtils was unable to locate the Serialize Context.");
+            return result;
+        }
+
+        AZ::Entity* FindEntity(AZ::EntityId entityId, AzToolsFramework::Prefab::Instance& source)
+        {
+            AZ::Entity* result = nullptr;
+            source.GetEntities(
+                [&result, entityId](AZStd::unique_ptr<AZ::Entity>& entity)
+                {
+                    if (entity->GetId() != entityId)
+                    {
+                        return true;
+                    }
+                    else
+                    {
+                        result = entity.get();
+                        return false;
+                    }
+                });
+            return result;
+        }
+
+        AZ::Entity* FindEntity(AZ::EntityId entityId, AzFramework::Spawnable& source)
+        {
+            uint32_t index = AzToolsFramework::Prefab::SpawnableUtils::FindEntityIndex(entityId, source);
+            return index != InvalidEntityIndex ? source.GetEntities()[index].get() : nullptr;
+        }
+
+        template<typename T>
+        AZStd::unique_ptr<AZ::Entity> CloneEntity(AZ::EntityId entityId, T& source)
+        {
+            AZ::Entity* target = Internal::FindEntity(entityId, source);
+            AZ_Assert(
+                target, "SpawnbleUtils were unable to locate entity with id %zu in Instance or Spawnable for cloning.",
+                aznumeric_cast<AZ::u64>(entityId));
+            auto clone = AZStd::make_unique<AZ::Entity>();
+
+            static AZ::SerializeContext* sc = GetSerializeContext();
+            sc->CloneObjectInplace(*clone, target);
+            clone->SetId(AZ::Entity::MakeId());
+
+            return clone;        
+        }
+
+        AZStd::unique_ptr<AZ::Entity> ReplaceEntityWithPlaceholder(AZ::EntityId entityId, AzToolsFramework::Prefab::Instance& source)
+        {
+            auto&& [instance, alias] = source.FindInstanceAndAlias(entityId);
+            AZ_Assert(
+                instance, "SpawnbleUtils were unable to locate entity alias with id %zu in Instance '%s' for replacing.",
+                aznumeric_cast<AZ::u64>(entityId), source.GetTemplateSourcePath().c_str());
+
+            EntityOptionalReference entityData = instance->GetEntity(alias);
+            AZ_Assert(
+                entityData.has_value(), "SpawnbleUtils were unable to locate entity '%.*s' in Instance '%s' for replacing.",
+                AZ_STRING_ARG(alias), source.GetTemplateSourcePath().c_str());
+            auto placeholder = AZStd::make_unique<AZ::Entity>(entityData->get().GetId(), entityData->get().GetName());
+            return instance->ReplaceEntity(AZStd::move(placeholder), alias);
+        }
+
+        AZStd::unique_ptr<AZ::Entity> ReplaceEntityWithPlaceholder(AZ::EntityId entityId, AzFramework::Spawnable& source)
+        {
+            uint32_t index = AzToolsFramework::Prefab::SpawnableUtils::FindEntityIndex(entityId, source);
+            AZ_Assert(
+                index != InvalidEntityIndex, "SpawnbleUtils were unable to locate entity alias with id %zu in Spawnable for replacing.",
+                aznumeric_cast<AZ::u64>(entityId));
+
+            AZStd::unique_ptr<AZ::Entity> original = AZStd::move(source.GetEntities()[index]);
+            AZ_Assert(
+                original, "SpawnbleUtils were unable to locate entity with id %zu in Spawnable for replacing.",
+                aznumeric_cast<AZ::u64>(entityId));
+
+            source.GetEntities()[index] = AZStd::make_unique<AZ::Entity>(original->GetId(), original->GetName());
+            
+            return original;
+        }
+
+        template<typename Source>
+        AZStd::pair<AZStd::unique_ptr<AZ::Entity>, AzFramework::Spawnable::EntityAliasType> ApplyAlias(
+            Source& source, AZ::EntityId entityId, AzToolsFramework::Prefab::PrefabConversionUtils::EntityAliasType aliasType)
+        {
+            namespace PCU = AzToolsFramework::Prefab::PrefabConversionUtils;
+            using ResultPair = AZStd::pair<AZStd::unique_ptr<AZ::Entity>, AzFramework::Spawnable::EntityAliasType>;
+
+            switch (aliasType)
+            {
+            case PCU::EntityAliasType::Disable:
+                // No need to do anything as the alias is disabled.
+                return ResultPair(nullptr, AzFramework::Spawnable::EntityAliasType::Disable);
+            case PCU::EntityAliasType::OptionalReplace:
+                return ResultPair(CloneEntity(entityId, source), AzFramework::Spawnable::EntityAliasType::Replace);
+            case PCU::EntityAliasType::Replace:
+                return ResultPair(ReplaceEntityWithPlaceholder(entityId, source), AzFramework::Spawnable::EntityAliasType::Replace);
+            case PCU::EntityAliasType::Additional:
+                ResultPair(AZStd::make_unique<AZ::Entity>(AZ::Entity::MakeId()), AzFramework::Spawnable::EntityAliasType::Additional);
+            case PCU::EntityAliasType::Merge:
+                // Use the same entity id as the original entity so at runtime the entity ids can be verified to match.
+                ResultPair(AZStd::make_unique<AZ::Entity>(entityId), AzFramework::Spawnable::EntityAliasType::Merge);
+            default:
+                AZ_Assert(
+                    false, "Invalid PrefabProcessorContext::EntityAliasType type (%i) provided.", aznumeric_cast<uint64_t>(aliasType));
+                return ResultPair(nullptr, AzFramework::Spawnable::EntityAliasType::Disable);
+            }
+        }
+    }
+
     bool CreateSpawnable(AzFramework::Spawnable& spawnable, const PrefabDom& prefabDom)
     {
         AZStd::vector<AZ::Data::Asset<AZ::Data::AssetData>> referencedAssets;
         return CreateSpawnable(spawnable, prefabDom, referencedAssets);
     }
 
-    bool CreateSpawnable(AzFramework::Spawnable& spawnable, const PrefabDom& prefabDom, AZStd::vector<AZ::Data::Asset<AZ::Data::AssetData>>& referencedAssets)
+    bool CreateSpawnable(
+        AzFramework::Spawnable& spawnable,
+        const PrefabDom& prefabDom,
+        AZStd::vector<AZ::Data::Asset<AZ::Data::AssetData>>& referencedAssets)
     {
         Instance instance;
-        if (Prefab::PrefabDomUtils::LoadInstanceFromPrefabDom(instance, prefabDom, referencedAssets,
-            Prefab::PrefabDomUtils::LoadFlags::AssignRandomEntityId)) // Always assign random entity ids because the spawnable is
-                                                                              // going to be used to create clones of the entities.
+        if (Prefab::PrefabDomUtils::LoadInstanceFromPrefabDom(
+                instance, prefabDom, referencedAssets,
+                Prefab::PrefabDomUtils::LoadFlags::AssignRandomEntityId)) // Always assign random entity ids because the spawnable is
+                                                                          // going to be used to create clones of the entities.
         {
             AzFramework::Spawnable::EntityList& entities = spawnable.GetEntities();
             instance.DetachAllEntitiesInHierarchy(
@@ -47,6 +166,144 @@ namespace AzToolsFramework::Prefab::SpawnableUtils
         }
     }
 
+    AZ::Entity* CreateEntityAlias(
+        AZStd::string sourcePrefabName,
+        AzToolsFramework::Prefab::Instance& source,
+        AZStd::string targetPrefabName,
+        AzToolsFramework::Prefab::Instance& target,
+        AZ::EntityId entityId,
+        AzToolsFramework::Prefab::PrefabConversionUtils::EntityAliasType aliasType,
+        AzToolsFramework::Prefab::PrefabConversionUtils::EntityAliasSpawnableLoadBehavior loadBehavior,
+        uint32_t tag,
+        AzToolsFramework::Prefab::PrefabConversionUtils::PrefabProcessorContext& context)
+    {
+        using namespace AzToolsFramework::Prefab::PrefabConversionUtils;
+
+        AliasPath alias = source.GetAliasPathRelativeToInstance(entityId);
+        if (!alias.empty())
+        {
+            auto&& [replacement, storedAliasType] = Internal::ApplyAlias(source, entityId, aliasType);
+            if (replacement)
+            {
+                AZ::Entity* result = replacement.get();
+                target.AddEntity(AZStd::move(replacement), alias.Filename().Native());
+
+                EntityAliasStore store;
+                store.m_aliasType = storedAliasType;
+                store.m_source.emplace<EntityAliasPrefabLink>(AZStd::move(sourcePrefabName), AZStd::move(alias));
+                store.m_target.emplace<EntityAliasPrefabLink>(
+                    AZStd::move(targetPrefabName), target.GetAliasPathRelativeToInstance(result->GetId()));
+                store.m_loadBehavior = loadBehavior;
+                store.m_tag = tag;
+                context.RegisterSpawnableEntityAlias(AZStd::move(store));
+
+                return result;
+            }
+            else
+            {
+                AZ_Assert(false, "A replacement for entity with id %zu could not be created.", static_cast<AZ::u64>(entityId));
+                return nullptr;
+            }
+        }
+        else
+        {
+            AZ_Assert(false, "Entity with id %zu was not found in the source prefab.", static_cast<AZ::u64>(entityId));
+            return nullptr;
+        }
+    }
+
+    AZ::Entity* CreateEntityAlias(
+        AZStd::string sourcePrefabName,
+        AzToolsFramework::Prefab::Instance& source,
+        AzFramework::Spawnable& target,
+        AZ::EntityId entityId,
+        AzToolsFramework::Prefab::PrefabConversionUtils::EntityAliasType aliasType,
+        AzToolsFramework::Prefab::PrefabConversionUtils::EntityAliasSpawnableLoadBehavior loadBehavior,
+        uint32_t tag,
+        AzToolsFramework::Prefab::PrefabConversionUtils::PrefabProcessorContext& context)
+    {
+        using namespace AzToolsFramework::Prefab::PrefabConversionUtils;
+
+        AliasPath alias = source.GetAliasPathRelativeToInstance(entityId);
+        if (!alias.empty())
+        {
+            auto&& [replacement, storedAliasType] = Internal::ApplyAlias(source, entityId, aliasType);
+            if (replacement)
+            {
+                AZ::Entity* result = replacement.get();
+                target.GetEntities().push_back(AZStd::move(replacement));
+
+                EntityAliasStore store;
+                store.m_aliasType = storedAliasType;
+                store.m_source.emplace<EntityAliasPrefabLink>(AZStd::move(sourcePrefabName), AZStd::move(alias));
+                store.m_target.emplace<EntityAliasSpawnableLink>(target, result->GetId());
+                store.m_tag = tag;
+                store.m_loadBehavior = loadBehavior;
+                context.RegisterSpawnableEntityAlias(AZStd::move(store));
+
+                return result;
+            }
+            else
+            {
+                AZ_Assert(false, "A replacement for entity with id %zu could not be created.", static_cast<AZ::u64>(entityId));
+                return nullptr;
+            }
+        }
+        else
+        {
+            AZ_Assert(false, "Entity with id %llu was not found in the source prefab.", static_cast<AZ::u64>(entityId));
+            return nullptr;
+        }
+    }
+
+    AZ::Entity* CreateEntityAlias(
+        AzFramework::Spawnable& source,
+        AzFramework::Spawnable& target,
+        AZ::EntityId entityId,
+        AzToolsFramework::Prefab::PrefabConversionUtils::EntityAliasType aliasType,
+        AzToolsFramework::Prefab::PrefabConversionUtils::EntityAliasSpawnableLoadBehavior loadBehavior,
+        uint32_t tag,
+        AzToolsFramework::Prefab::PrefabConversionUtils::PrefabProcessorContext& context)
+    {
+        using namespace AzToolsFramework::Prefab::PrefabConversionUtils;
+
+        auto&& [replacement, storedAliasType] = Internal::ApplyAlias(source, entityId, aliasType);
+        if (replacement)
+        {
+            AZ::Entity* result = replacement.get();
+            target.GetEntities().push_back(AZStd::move(replacement));
+
+            EntityAliasStore store;
+            store.m_aliasType = storedAliasType;
+            store.m_source.emplace<EntityAliasSpawnableLink>(source, entityId);
+            store.m_target.emplace<EntityAliasSpawnableLink>(target, result->GetId());
+            store.m_tag = tag;
+            store.m_loadBehavior = loadBehavior;
+            context.RegisterSpawnableEntityAlias(AZStd::move(store));
+
+            return result;
+        }
+        else
+        {
+            AZ_Assert(false, "A replacement for entity with id %zu could not be created.", static_cast<AZ::u64>(entityId));
+            return nullptr;
+        }
+    }
+
+    uint32_t FindEntityIndex(AZ::EntityId entity, const AzFramework::Spawnable& spawnable)
+    {
+        auto begin = spawnable.GetEntities().begin();
+        auto end = spawnable.GetEntities().end();
+        for(auto it = begin; it != end; ++it)
+        {
+            if ((*it)->GetId() == entity)
+            {
+                return aznumeric_caster(AZStd::distance(begin, it));
+            }
+        }
+        return InvalidEntityIndex;
+    }
+
     template<typename EntityPtr>
     void OrganizeEntitiesForSorting(
         AZStd::vector<EntityPtr>& entities,

Code/Framework/AzToolsFramework/AzToolsFramework/Prefab/Spawnable/SpawnableUtils.h

@@ -8,14 +8,59 @@
 
 #pragma once
 
+#include <AzCore/Component/EntityId.h>
+#include <AzCore/std/limits.h>
 #include <AzFramework/Spawnable/Spawnable.h>
 #include <AzToolsFramework/Prefab/PrefabDomTypes.h>
+#include <AzToolsFramework/Prefab/Spawnable/PrefabProcessorContext.h>
+
+namespace AZ
+{
+    class Entity;
+}
+
+namespace AzToolsFramework::Prefab
+{
+    class Instance;
+}
 
 namespace AzToolsFramework::Prefab::SpawnableUtils
 {
+    static constexpr uint32_t InvalidEntityIndex = AZStd::numeric_limits<uint32_t>::max();
+
     bool CreateSpawnable(AzFramework::Spawnable& spawnable, const PrefabDom& prefabDom);
     bool CreateSpawnable(AzFramework::Spawnable& spawnable, const PrefabDom& prefabDom, AZStd::vector<AZ::Data::Asset<AZ::Data::AssetData>>& referencedAssets);
 
+    AZ::Entity* CreateEntityAlias(
+        AZStd::string sourcePrefabName,
+        AzToolsFramework::Prefab::Instance& source,
+        AZStd::string targetPrefabName,
+        AzToolsFramework::Prefab::Instance& target,
+        AZ::EntityId entityId,
+        AzToolsFramework::Prefab::PrefabConversionUtils::EntityAliasType aliasType,
+        AzToolsFramework::Prefab::PrefabConversionUtils::EntityAliasSpawnableLoadBehavior loadBehavior,
+        uint32_t tag,
+        AzToolsFramework::Prefab::PrefabConversionUtils::PrefabProcessorContext& context);
+    AZ::Entity* CreateEntityAlias(
+        AZStd::string sourcePrefabName,
+        AzToolsFramework::Prefab::Instance& source,
+        AzFramework::Spawnable& target,
+        AZ::EntityId entityId,
+        AzToolsFramework::Prefab::PrefabConversionUtils::EntityAliasType aliasType,
+        AzToolsFramework::Prefab::PrefabConversionUtils::EntityAliasSpawnableLoadBehavior loadBehavior,
+        uint32_t tag,
+        AzToolsFramework::Prefab::PrefabConversionUtils::PrefabProcessorContext& context);
+    AZ::Entity* CreateEntityAlias(
+        AzFramework::Spawnable& source,
+        AzFramework::Spawnable& target,
+        AZ::EntityId entityId,
+        AzToolsFramework::Prefab::PrefabConversionUtils::EntityAliasType aliasType,
+        AzToolsFramework::Prefab::PrefabConversionUtils::EntityAliasSpawnableLoadBehavior loadBehavior,
+        uint32_t tag,
+        AzToolsFramework::Prefab::PrefabConversionUtils::PrefabProcessorContext& context);
+
+    uint32_t FindEntityIndex(AZ::EntityId entity, const AzFramework::Spawnable& spawnable);
+
     void SortEntitiesByTransformHierarchy(AzFramework::Spawnable& spawnable);
 
     template <typename EntityPtr>

Code/Framework/AzToolsFramework/Tests/UI/AssetBrowserTests.cpp

@@ -0,0 +1,344 @@
+/*
+ * Copyright (c) Contributors to the Open 3D Engine Project.
+ * For complete copyright and license terms please see the LICENSE at the root of this distribution.
+ *
+ * SPDX-License-Identifier: Apache-2.0 OR MIT
+ *
+ */
+
+#include <AzTest/AzTest.h>
+
+#include <AzToolsFramework/AssetBrowser/AssetBrowserComponent.h>
+#include <AzToolsFramework/AssetBrowser/AssetBrowserFilterModel.h>
+#include <AzToolsFramework/AssetBrowser/AssetBrowserModel.h>
+#include <AzToolsFramework/AssetBrowser/AssetBrowserTableModel.h>
+#include <AzToolsFramework/AssetBrowser/Entries/AssetBrowserEntry.h>
+#include <AzToolsFramework/AssetBrowser/Entries/FolderAssetBrowserEntry.h>
+#include <AzToolsFramework/AssetBrowser/Entries/ProductAssetBrowserEntry.h>
+#include <AzToolsFramework/AssetBrowser/Entries/RootAssetBrowserEntry.h>
+#include <AzToolsFramework/AssetBrowser/Entries/SourceAssetBrowserEntry.h>
+#include <AzToolsFramework/AssetBrowser/Search/SearchWidget.h>
+#include <AzToolsFramework/AssetDatabase/AssetDatabaseConnection.h>
+#include <AzToolsFramework/Entity/EditorEntityContextComponent.h>
+#include <AzToolsFramework/UnitTest/AzToolsFrameworkTestHelpers.h>
+#include <QAbstractItemModelTester>
+
+namespace UnitTest
+{
+    // Test fixture for the AssetBrowser model that uses a QAbstractItemModelTester to validate the state of the model
+    // when QAbstractItemModel signals fire. Tests will exit with a fatal error if an invalid state is detected.
+    class AssetBrowserTest
+        : public ToolsApplicationFixture
+        , public testing::WithParamInterface<const char*>
+    {
+    protected:
+        enum class AssetEntryType
+        {
+            Root,
+            Folder,
+            Source,
+            Product
+        };
+
+        enum class FolderType
+        {
+            Root,
+            File
+        };
+
+        void SetUpEditorFixtureImpl() override;
+        void TearDownEditorFixtureImpl() override;
+
+        //! Creates a Mock Scan Folder
+        void AddScanFolder(AZ::s64 folderID, AZStd::string folderPath, AZStd::string displayName, FolderType folderType = FolderType::File);
+
+        //! Creates a Source entry from a mock file
+        AZ::Uuid CreateSourceEntry(
+            AZ::s64 fileID, AZ::s64 parentFolderID, AZStd::string filename, AssetEntryType sourceType = AssetEntryType::Source);
+
+        //! Creates a product from a given sourceEntry
+        void CreateProduct(AZ::s64 productID, AZ::Uuid sourceUuid, AZStd::string productName);
+
+        void SetupAssetBrowser();
+        void PrintModel(const QAbstractItemModel* model, AZStd::function<void(const QString&)> printer);
+        QModelIndex GetModelIndex(const QAbstractItemModel* model, int targetDepth, int row = 0);
+        AZStd::shared_ptr<AzToolsFramework::AssetBrowser::RootAssetBrowserEntry> GetRootEntry();
+        AZStd::vector<QString> GetVectorFromFormattedString(const QString& formattedString);
+
+    protected:
+        QString m_assetBrowserHierarchy = QString();
+
+        AZStd::unique_ptr<AzToolsFramework::AssetBrowser::SearchWidget> m_searchWidget;
+        AZStd::unique_ptr<AzToolsFramework::AssetBrowser::AssetBrowserComponent> m_assetBrowserComponent;
+
+        AZStd::unique_ptr<AzToolsFramework::AssetBrowser::AssetBrowserFilterModel> m_filterModel;
+        AZStd::unique_ptr<AzToolsFramework::AssetBrowser::AssetBrowserTableModel> m_tableModel;
+
+        AZStd::unique_ptr<QAbstractItemModelTester> m_modelTesterAssetBrowser;
+        AZStd::unique_ptr<QAbstractItemModelTester> m_modelTesterFilterModel;
+        AZStd::unique_ptr<QAbstractItemModelTester> m_modelTesterTableModel;
+
+        QVector<int> m_folderIds = { 13, 14, 15 };
+        QVector<int> m_sourceIDs = { 1, 2, 3, 4, 5 };
+        QVector<int> m_productIDs = { 1, 2, 3, 4, 5 };
+    };
+
+    void AssetBrowserTest::SetUpEditorFixtureImpl()
+    {
+        GetApplication()->RegisterComponentDescriptor(AzToolsFramework::EditorEntityContextComponent::CreateDescriptor());
+
+        m_assetBrowserComponent = AZStd::make_unique<AzToolsFramework::AssetBrowser::AssetBrowserComponent>();
+        m_assetBrowserComponent->Activate();
+
+        m_filterModel = AZStd::make_unique<AzToolsFramework::AssetBrowser::AssetBrowserFilterModel>();
+        m_tableModel = AZStd::make_unique<AzToolsFramework::AssetBrowser::AssetBrowserTableModel>();
+
+        m_filterModel->setSourceModel(m_assetBrowserComponent->GetAssetBrowserModel());
+        m_tableModel->setSourceModel(m_filterModel.get());
+
+        m_modelTesterAssetBrowser = AZStd::make_unique<QAbstractItemModelTester>(m_assetBrowserComponent->GetAssetBrowserModel());
+        m_modelTesterFilterModel = AZStd::make_unique<QAbstractItemModelTester>(m_filterModel.get());
+        m_modelTesterTableModel = AZStd::make_unique<QAbstractItemModelTester>(m_tableModel.get());
+        m_searchWidget = AZStd::make_unique<AzToolsFramework::AssetBrowser::SearchWidget>();
+
+        // Setup String filters
+        m_searchWidget->Setup(true, true);
+        m_filterModel->SetFilter(m_searchWidget->GetFilter());
+
+        SetupAssetBrowser();
+    }
+
+    void AssetBrowserTest::TearDownEditorFixtureImpl()
+    {
+        m_modelTesterAssetBrowser.reset();
+        m_modelTesterFilterModel.reset();
+        m_modelTesterTableModel.reset();
+
+        m_tableModel.reset();
+        m_filterModel.reset();
+        m_assetBrowserComponent->Deactivate();
+
+        m_assetBrowserComponent.reset();
+        m_searchWidget.reset();
+    }
+
+    void AssetBrowserTest::AddScanFolder(
+        AZ::s64 folderID, AZStd::string folderPath, AZStd::string displayName, FolderType folderType /*= FolderType::File*/)
+    {
+        AzToolsFramework::AssetDatabase::ScanFolderDatabaseEntry scanFolder = AzToolsFramework::AssetDatabase::ScanFolderDatabaseEntry();
+        scanFolder.m_scanFolderID = folderID;
+        scanFolder.m_scanFolder = folderPath;
+        scanFolder.m_displayName = displayName;
+        scanFolder.m_isRoot = folderType == FolderType::Root;
+        GetRootEntry()->AddScanFolder(scanFolder);
+    }
+
+    AZ::Uuid AssetBrowserTest::CreateSourceEntry(
+        AZ::s64 fileID, AZ::s64 parentFolderID, AZStd::string filename, AssetEntryType sourceType /*= AssetEntryType::Source*/)
+    {
+        AzToolsFramework::AssetDatabase::FileDatabaseEntry entry = AzToolsFramework::AssetDatabase::FileDatabaseEntry();
+        entry.m_scanFolderPK = parentFolderID;
+        entry.m_fileID = fileID;
+        entry.m_fileName = filename;
+        entry.m_isFolder = sourceType == AssetEntryType::Folder;
+        GetRootEntry()->AddFile(entry);
+
+        if (!entry.m_isFolder)
+        {
+            AzToolsFramework::AssetBrowser::SourceWithFileID entrySource = AzToolsFramework::AssetBrowser::SourceWithFileID();
+            entrySource.first = entry.m_fileID;
+            entrySource.second = AzToolsFramework::AssetDatabase::SourceDatabaseEntry();
+            entrySource.second.m_scanFolderPK = parentFolderID;
+            entrySource.second.m_sourceName = filename;
+            entrySource.second.m_sourceID = fileID;
+            entrySource.second.m_sourceGuid = AZ::Uuid::CreateRandom();
+
+            GetRootEntry()->AddSource(entrySource);
+
+            return entrySource.second.m_sourceGuid;
+        }
+
+        return AZ::Uuid::CreateNull();
+    }
+
+    void AssetBrowserTest::CreateProduct(AZ::s64 productID, AZ::Uuid sourceUuid, AZStd::string productName)
+    {
+        AzToolsFramework::AssetBrowser::ProductWithUuid product = AzToolsFramework::AssetBrowser::ProductWithUuid();
+        product.first = sourceUuid;
+        product.second = AzToolsFramework::AssetDatabase::ProductDatabaseEntry();
+        product.second.m_productID = productID;
+
+        product.second.m_subID = aznumeric_cast<AZ::u32>(productID);
+        product.second.m_productName = productName;
+
+        GetRootEntry()->AddProduct(product);
+    }
+
+    void AssetBrowserTest::SetupAssetBrowser()
+    {
+        // RootEntries : 1 | Folders : 4 | SourceEntries : 5 | ProductEntries : 9
+        m_assetBrowserHierarchy = R"(
+        D:
+          \
+            dev
+              o3de
+                GameProject
+                  Assets
+                    Source_1
+                      Product_1_1
+                      Product_1_0
+                    Source_0
+                      Product_0_3
+                      Product_0_2
+                      Product_0_1
+                      Product_0_0
+                  Scripts
+                    Source_3
+                    Source_2
+                      Product_2_2
+                      Product_2_1
+                      Product_2_0
+                  Misc
+                    Source_4
+                      Product_4_2
+                      Product_4_1
+                      Product_4_0 )";
+
+        namespace AzAssetBrowser = AzToolsFramework::AssetBrowser;
+
+        AddScanFolder(m_folderIds.at(2), "D:/dev/o3de/GameProject/Misc", "Misc");
+        AZ::Uuid sourceUuid_4 = CreateSourceEntry(m_sourceIDs.at(4), m_folderIds.at(2), "Source_4");
+        CreateProduct(m_productIDs.at(0), sourceUuid_4, "Product_4_0");
+        CreateProduct(m_productIDs.at(1), sourceUuid_4, "Product_4_1");
+        CreateProduct(m_productIDs.at(2), sourceUuid_4, "Product_4_2");
+
+        AddScanFolder(m_folderIds.at(1), "D:/dev/o3de/GameProject/Scripts", "Scripts");
+
+        AZ::Uuid sourceUuid_2 = CreateSourceEntry(m_sourceIDs.at(2), m_folderIds.at(1), "Source_2");
+        CreateProduct(m_productIDs.at(0), sourceUuid_2, "Product_2_0");
+        CreateProduct(m_productIDs.at(1), sourceUuid_2, "Product_2_1");
+        CreateProduct(m_productIDs.at(2), sourceUuid_2, "Product_2_2");
+
+        CreateSourceEntry(m_sourceIDs.at(3), m_folderIds.at(1), "Source_3");
+
+        AddScanFolder(m_folderIds.at(0), "D:/dev/o3de/GameProject/Assets", "Assets");
+
+        AZ::Uuid sourceUuid_0 = CreateSourceEntry(m_sourceIDs.at(0), m_folderIds.at(0), "Source_0");
+        CreateProduct(m_productIDs.at(0), sourceUuid_0, "Product_0_0");
+        CreateProduct(m_productIDs.at(1), sourceUuid_0, "Product_0_1");
+        CreateProduct(m_productIDs.at(2), sourceUuid_0, "Product_0_2");
+        CreateProduct(m_productIDs.at(3), sourceUuid_0, "Product_0_3");
+
+        AZ::Uuid sourceUuid_1 = CreateSourceEntry(m_sourceIDs.at(1), m_folderIds.at(0), "Source_1");
+        CreateProduct(m_productIDs.at(0), sourceUuid_1, "Product_1_0");
+        CreateProduct(m_productIDs.at(1), sourceUuid_1, "Product_1_1");
+    }
+
+    void AssetBrowserTest::PrintModel(const QAbstractItemModel* model, AZStd::function<void(const QString&)> printer)
+    {
+        AZStd::deque<AZStd::pair<QModelIndex, int>> indices;
+        indices.push_back({ model->index(0, 0), 0 });
+        while (!indices.empty())
+        {
+            auto [index, depth] = indices.front();
+            indices.pop_front();
+
+            QString indentString;
+            for (int i = 0; i < depth; ++i)
+            {
+                indentString += "  ";
+            }
+            const QString message = indentString + index.data(Qt::DisplayRole).toString();
+            printer(message);
+
+            for (int i = 0; i < model->rowCount(index); ++i)
+            {
+                indices.emplace_front(model->index(i, 0, index), depth + 1);
+            }
+        }
+    }
+
+    QModelIndex AssetBrowserTest::GetModelIndex(const QAbstractItemModel* model, int targetDepth, int row)
+    {
+        AZStd::deque<AZStd::pair<QModelIndex, int>> indices;
+        indices.push_back({ model->index(0, 0), 0 });
+        while (!indices.empty())
+        {
+            auto [index, depth] = indices.front();
+            indices.pop_front();
+
+            for (int i = 0; i < model->rowCount(index); ++i)
+            {
+                if (depth + 1 == targetDepth && row == i)
+                {
+                    return model->index(i, 0, index);
+                }
+                indices.emplace_front(model->index(i, 0, index), depth + 1);
+            }
+        }
+        return QModelIndex();
+    }
+
+    AZStd::shared_ptr<AzToolsFramework::AssetBrowser::RootAssetBrowserEntry> AssetBrowserTest::GetRootEntry()
+    {
+        return m_assetBrowserComponent->GetAssetBrowserModel()->GetRootEntry();
+    }
+
+    AZStd::vector<QString> AssetBrowserTest::GetVectorFromFormattedString(const QString& formattedString)
+    {
+        AZStd::vector<QString> hierarchySections;
+        QStringList splittedList = formattedString.split('\n', Qt::SkipEmptyParts);
+
+        for (auto& str : splittedList)
+        {
+            str.replace(" ", "");
+            hierarchySections.push_back(str);
+        }
+        return hierarchySections;
+    }
+
+    TEST_F(AssetBrowserTest, CheckCorrectNumberOfEntriesInTableView)
+    {
+        m_filterModel->FilterUpdatedSlotImmediate();
+        const int tableViewRowcount = m_tableModel->rowCount();
+
+        // RowCount should be 17 -> 5 SourceEntries + 12 ProductEntries)
+        EXPECT_EQ(tableViewRowcount, 17);
+    }
+
+    TEST_F(AssetBrowserTest, CheckCorrectNumberOfEntriesInTableViewAfterStringFilter)
+    {
+        /*
+         *-Source_1
+         * |
+         * |-product_1_0
+         * |-product_1_1
+         *
+         *
+         * Matching entries = 3
+         */
+
+        // Apply string filter
+        m_searchWidget->SetTextFilter(QString("source_1"));
+        m_filterModel->FilterUpdatedSlotImmediate();
+
+        const int tableViewRowcount = m_tableModel->rowCount();
+        EXPECT_EQ(tableViewRowcount, 3);
+    }
+
+    TEST_F(AssetBrowserTest, CheckScanFolderAddition)
+    {
+        EXPECT_EQ(m_assetBrowserComponent->GetAssetBrowserModel()->rowCount(), 1);
+        const int newFolderId = 20;
+        AddScanFolder(newFolderId, "E:/TestFolder/TestFolder2", "TestFolder");
+
+        // Since the folder is empty it shouldn't be added to the model.
+        EXPECT_EQ(m_assetBrowserComponent->GetAssetBrowserModel()->rowCount(), 1);
+
+        CreateSourceEntry(123, newFolderId, "DummyFile");
+
+        // When we add a file to the folder it should be added to the model
+        EXPECT_EQ(m_assetBrowserComponent->GetAssetBrowserModel()->rowCount(), 2);
+    }
+
+} // namespace UnitTest

Code/Framework/AzToolsFramework/Tests/UI/EntityOutlinerTests.cpp

@@ -82,8 +82,8 @@ namespace UnitTest
             }
 
             auto transform = aznew AzToolsFramework::Components::TransformComponent;
-            transform->SetParent(parentId);
             entity->AddComponent(transform);
+            transform->SetParent(parentId);
 
             entity->Activate();
 

Code/Framework/AzToolsFramework/Tests/aztoolsframeworktests_files.cmake

@@ -126,6 +126,7 @@ set(FILES
     UI/EntityIdQLineEditTests.cpp
     UI/EntityOutlinerTests.cpp
     UI/EntityPropertyEditorTests.cpp
+    UI/AssetBrowserTests.cpp
     UndoStack.cpp
     Viewport/ClusterTests.cpp
     Viewport/ViewportEditorModeTests.cpp

Code/LauncherUnified/Launcher.cpp

@@ -25,7 +25,6 @@
 
 #include <AzGameFramework/Application/GameApplication.h>
 
-#include <CryLibrary.h>
 #include <ISystem.h>
 #include <ITimer.h>
 #include <LegacyAllocator.h>
@@ -80,146 +79,6 @@ namespace
         }
     }
 
-#if AZ_TRAIT_LAUNCHER_USE_CRY_DYNAMIC_MODULE_HANDLE
-    // mimics AZ::DynamicModuleHandle but uses CryLibrary under the hood,
-    // which is necessary to properly load legacy Cry libraries on some platforms
-    class DynamicModuleHandle
-    {
-    public:
-        AZ_CLASS_ALLOCATOR(DynamicModuleHandle, AZ::OSAllocator, 0)
-
-        static AZStd::unique_ptr<DynamicModuleHandle> Create(const char* fullFileName)
-        {
-            return AZStd::unique_ptr<DynamicModuleHandle>(aznew DynamicModuleHandle(fullFileName));
-        }
-
-        DynamicModuleHandle(const DynamicModuleHandle&) = delete;
-        DynamicModuleHandle& operator=(const DynamicModuleHandle&) = delete;
-
-        ~DynamicModuleHandle()
-        {
-            Unload();
-        }
-
-        // argument is strictly to match the API of AZ::DynamicModuleHandle
-        bool Load(bool unused)
-        {
-            AZ_UNUSED(unused);
-
-            if (IsLoaded())
-            {
-                return true;
-            }
-
-            m_moduleHandle = CryLoadLibrary(m_fileName.c_str());
-            return IsLoaded();
-        }
-
-        bool Unload()
-        {
-            if (!IsLoaded())
-            {
-                return false;
-            }
-
-            return CryFreeLibrary(m_moduleHandle);
-        }
-
-        bool IsLoaded() const
-        {
-            return m_moduleHandle != nullptr;
-        }
-
-        const AZ::OSString& GetFilename() const
-        {
-            return m_fileName;
-        }
-
-        template<typename Function>
-        Function GetFunction(const char* functionName) const
-        {
-            if (IsLoaded())
-            {
-                return reinterpret_cast<Function>(CryGetProcAddress(m_moduleHandle, functionName));
-            }
-            else
-            {
-                return nullptr;
-            }
-        }
-
-
-    private:
-        DynamicModuleHandle(const char* fileFullName)
-            : m_fileName()
-            , m_moduleHandle(nullptr)
-        {
-            m_fileName = AZ::OSString::format("%s%s%s",
-                CrySharedLibraryPrefix, fileFullName, CrySharedLibraryExtension);
-        }
-
-        AZ::OSString m_fileName;
-        HMODULE m_moduleHandle;
-    };
-#else
-    // mimics AZ::DynamicModuleHandle but also calls InjectEnvironmentFunction on
-    // the loaded module which is necessary to properly load legacy Cry libraries
-    class DynamicModuleHandle
-    {
-    public:
-        AZ_CLASS_ALLOCATOR(DynamicModuleHandle, AZ::OSAllocator, 0);
-
-        static AZStd::unique_ptr<DynamicModuleHandle> Create(const char* fullFileName)
-        {
-            return AZStd::unique_ptr<DynamicModuleHandle>(aznew DynamicModuleHandle(fullFileName));
-        }
-
-        bool Load(bool isInitializeFunctionRequired)
-        {
-            const bool loaded = m_moduleHandle->Load(isInitializeFunctionRequired);
-            if (loaded)
-            {
-                // We need to inject the environment first thing so that allocators are available immediately
-                InjectEnvironmentFunction injectEnv = GetFunction<InjectEnvironmentFunction>(INJECT_ENVIRONMENT_FUNCTION);
-                if (injectEnv)
-                {
-                    auto env = AZ::Environment::GetInstance();
-                    injectEnv(env);
-                }
-            }
-            return loaded;
-        }
-
-        bool Unload()
-        {
-            bool unloaded = m_moduleHandle->Unload();
-            if (unloaded)
-            {
-                DetachEnvironmentFunction detachEnv = GetFunction<DetachEnvironmentFunction>(DETACH_ENVIRONMENT_FUNCTION);
-                if (detachEnv)
-                {
-                    detachEnv();
-                }
-            }
-            return unloaded;
-        }
-
-        template<typename Function>
-        Function GetFunction(const char* functionName) const
-        {
-            return m_moduleHandle->GetFunction<Function>(functionName);
-        }
-
-    private:
-        DynamicModuleHandle(const char* fileFullName)
-            : m_moduleHandle(AZ::DynamicModuleHandle::Create(fileFullName))
-        {
-        }
-
-        AZStd::unique_ptr<AZ::DynamicModuleHandle> m_moduleHandle;
-    };
-#endif // AZ_TRAIT_LAUNCHER_USE_CRY_DYNAMIC_MODULE_HANDLE
-
     void RunMainLoop(AzGameFramework::GameApplication& gameApplication)
     {
         // Ideally we'd just call GameApplication::RunMainLoop instead, but
@@ -649,13 +508,13 @@ namespace O3DELauncher
 
         // Create CrySystem.
     #if !defined(AZ_MONOLITHIC_BUILD)
-        AZStd::unique_ptr<DynamicModuleHandle> crySystemLibrary;
-        PFNCREATESYSTEMINTERFACE CreateSystemInterface = nullptr;
-
-        crySystemLibrary = DynamicModuleHandle::Create("CrySystem");
-        if (crySystemLibrary->Load(false))
+        constexpr const char* crySystemLibraryName = AZ_TRAIT_OS_DYNAMIC_LIBRARY_PREFIX  "CrySystem" AZ_TRAIT_OS_DYNAMIC_LIBRARY_EXTENSION;
+        AZStd::unique_ptr<AZ::DynamicModuleHandle> crySystemLibrary = AZ::DynamicModuleHandle::Create(crySystemLibraryName);
+        if (crySystemLibrary->Load(true))
         {
-            CreateSystemInterface = crySystemLibrary->GetFunction<PFNCREATESYSTEMINTERFACE>("CreateSystemInterface");
+            PFNCREATESYSTEMINTERFACE CreateSystemInterface =
+                crySystemLibrary->GetFunction<PFNCREATESYSTEMINTERFACE>("CreateSystemInterface");
+
             if (CreateSystemInterface)
             {
                 systemInitParams.pSystem = CreateSystemInterface(systemInitParams);

Code/LauncherUnified/Platform/Linux/Launcher_Linux.cpp

@@ -12,8 +12,6 @@
 #include <AzCore/IO/SystemFile.h> // for AZ_MAX_PATH_LEN
 #include <AzCore/Math/Vector2.h>
 
-#include <CryLibrary.h>
-
 #include <execinfo.h>
 #include <libgen.h>
 #include <netdb.h>
@@ -86,17 +84,6 @@ int main(int argc, char** argv)
 
     using namespace O3DELauncher;
 
-#if !defined(AZ_MONOLITHIC_BUILD)
-    char exePath[AZ_MAX_PATH_LEN] = { 0 };
-    if (readlink("/proc/self/exe", exePath, AZ_MAX_PATH_LEN) == -1)
-    {
-        return static_cast<int>(ReturnCode::ErrExePath);
-    }
-
-    char* runDir = dirname(exePath);
-    SetModulePath(runDir);
-#endif // !defined(AZ_MONOLITHIC_BUILD)
-
     PlatformMainInfo mainInfo;
 
     mainInfo.m_updateResourceLimits = IncreaseResourceLimits;