Procedural Prefabs: Entity parenting fixes (#4669)

* Parent top level entities to container entity when creating prefab

Signed-off-by: amzn-mike <80125227+amzn-mike@users.noreply.github.com>

* Add to_json method to PythonProxyObject to allow serializing any AZ serialializable type

Signed-off-by: amzn-mike <80125227+amzn-mike@users.noreply.github.com>

* Update scene_mesh_to_prefab.py to parent entities in a chain

Signed-off-by: amzn-mike <80125227+amzn-mike@users.noreply.github.com>

* Remove redundant eval

Signed-off-by: amzn-mike <80125227+amzn-mike@users.noreply.github.com>

* Improve error handling in ToJson

Signed-off-by: amzn-mike <80125227+amzn-mike@users.noreply.github.com>

* Add maybe_unused for commonRoot since it's not used

Signed-off-by: amzn-mike <80125227+amzn-mike@users.noreply.github.com>

AutomatedTesting/Editor/Scripts/scene_mesh_to_prefab.py

@@ -74,6 +74,7 @@ def update_manifest(scene):
     source_filename_only = os.path.basename(clean_filename)
 
     created_entities = []
+    previous_entity_id = azlmbr.entity.InvalidEntityId
 
     # Loop every mesh node in the scene
     for activeMeshIndex in range(len(mesh_name_list)):
@@ -102,14 +103,33 @@ def update_manifest(scene):
         # The MeshGroup we created will be output as a product in the asset's path named mesh_group_name.azmodel
         # The assetHint will be converted to an AssetId later during prefab loading
         json_update = json.dumps({
-                            "Controller": { "Configuration": { "ModelAsset": {
-                                "assetHint": os.path.join(source_relative_path, mesh_group_name) + ".azmodel" }}}
-                            });
+            "Controller": { "Configuration": { "ModelAsset": {
+                "assetHint": os.path.join(source_relative_path, mesh_group_name) + ".azmodel" }}}
+            });
         # Apply the JSON above to the component we created
         result = azlmbr.entity.EntityUtilityBus(azlmbr.bus.Broadcast, "UpdateComponentForEntity", entity_id, editor_mesh_component, json_update)
 
         if not result:
-            raise RuntimeError("UpdateComponentForEntity failed")
+            raise RuntimeError("UpdateComponentForEntity failed for Mesh component")
+
+        # Get the transform component
+        transform_component = azlmbr.entity.EntityUtilityBus(azlmbr.bus.Broadcast, "GetOrAddComponentByTypeName", entity_id, "27F1E1A1-8D9D-4C3B-BD3A-AFB9762449C0")
+
+        # Set this entity to be a child of the last entity we created
+        # This is just an example of how to do parenting and isn't necessarily useful to parent everything like this
+        if previous_entity_id is not None:
+            transform_json = json.dumps({
+                "Parent Entity" : previous_entity_id.to_json()
+                });
+
+            # Apply the JSON update
+            result = azlmbr.entity.EntityUtilityBus(azlmbr.bus.Broadcast, "UpdateComponentForEntity", entity_id, transform_component, transform_json)
+
+            if not result:
+                raise RuntimeError("UpdateComponentForEntity failed for Transform component")
+
+        # Update the last entity id for next time
+        previous_entity_id = entity_id
 
         # Keep track of the entity we set up, we'll add them all to the prefab we're creating later
         created_entities.append(entity_id)
@@ -147,6 +167,8 @@ def on_update_manifest(args):
     except RuntimeError as err:
         print (f'ERROR - {err}')
         log_exception_traceback()
+    except:
+        log_exception_traceback()
 
     global sceneJobHandler
     sceneJobHandler = None

Code/Framework/AzToolsFramework/AzToolsFramework/Prefab/PrefabSystemScriptingHandler.cpp

@@ -6,11 +6,14 @@
  *
  */
 
+#include <API/ToolsApplicationAPI.h>
 #include <AzCore/Component/ComponentApplicationBus.h>
 #include <AzCore/RTTI/BehaviorContext.h>
 #include <Prefab/PrefabSystemComponentInterface.h>
 #include <Prefab/PrefabSystemScriptingHandler.h>
 #include <AzCore/Component/Entity.h>
+#include <AzCore/Component/TransformBus.h>
+#include <ToolsComponents/TransformComponent.h>
 
 namespace AzToolsFramework::Prefab
 {
@@ -61,9 +64,29 @@ namespace AzToolsFramework::Prefab
                 entities.push_back(entity);
             }
         }
-        
-        auto prefab = m_prefabSystemComponentInterface->CreatePrefab(entities, {}, AZ::IO::PathView(AZStd::string_view(filePath)));
 
+        bool result = false;
+        [[maybe_unused]] AZ::EntityId commonRoot;
+        EntityList topLevelEntities;
+        AzToolsFramework::ToolsApplicationRequestBus::BroadcastResult(result, &AzToolsFramework::ToolsApplicationRequestBus::Events::FindCommonRootInactive,
+            entities, commonRoot, &topLevelEntities);
+
+        auto containerEntity = AZStd::make_unique<AZ::Entity>();
+
+        for (AZ::Entity* entity : topLevelEntities)
+        {
+            AzToolsFramework::Components::TransformComponent* transformComponent =
+                entity->FindComponent<AzToolsFramework::Components::TransformComponent>();
+
+            if (transformComponent)
+            {
+                transformComponent->SetParent(containerEntity->GetId());
+            }
+        }
+
+        auto prefab = m_prefabSystemComponentInterface->CreatePrefab(
+            entities, {}, AZ::IO::PathView(AZStd::string_view(filePath)), AZStd::move(containerEntity));
+        
         if (!prefab)
         {
             AZ_Error("PrefabSystemComponenent", false, "Failed to create prefab %s", filePath.c_str());

Gems/EditorPythonBindings/Code/Source/PythonProxyObject.cpp

@@ -17,10 +17,16 @@
 #include <Source/PythonSymbolsBus.h>
 
 #include <pybind11/embed.h>
+#include <pybind11/pybind11.h>
+#include <pybind11/eval.h>
 
 #include <AzCore/PlatformDef.h>
+#include <AzCore/JSON/rapidjson.h>
 #include <AzCore/RTTI/BehaviorContext.h>
 #include <AzCore/RTTI/AttributeReader.h>
+#include <AzCore/Serialization/Json/JsonSerialization.h>
+#include <AzCore/Serialization/Json/JsonSerializationSettings.h>
+#include <AzCore/Serialization/Json/JsonUtils.h>
 
 namespace EditorPythonBindings
 {
@@ -571,6 +577,37 @@ namespace EditorPythonBindings
         return false;
     }
 
+    pybind11::object PythonProxyObject::ToJson()
+    {
+        rapidjson::Document document;
+        AZ::JsonSerializerSettings settings;
+        settings.m_keepDefaults = true;
+        
+        auto resultCode =
+            AZ::JsonSerialization::Store(document, document.GetAllocator(), m_wrappedObject.m_address, nullptr, m_wrappedObject.m_typeId, settings);
+
+        if (resultCode.GetProcessing() == AZ::JsonSerializationResult::Processing::Halted)
+        {
+            AZ_Error("PythonProxyObject", false, "Failed to serialize to json");
+            return pybind11::cast<pybind11::none>(Py_None);
+        }
+
+        AZStd::string jsonString;
+        AZ::Outcome<void, AZStd::string> outcome = AZ::JsonSerializationUtils::WriteJsonString(document, jsonString);
+
+        if (!outcome.IsSuccess())
+        {
+            AZ_Error("PythonProxyObject", false, "Failed to write json string: %s", outcome.GetError().c_str());
+            return pybind11::cast<pybind11::none>(Py_None);
+        }
+        
+        jsonString.erase(AZStd::remove(jsonString.begin(), jsonString.end(), '\n'), jsonString.end());
+        auto pythonCode = AZStd::string::format(
+            R"PYTHON(exec("import json") or json.loads("""%s"""))PYTHON", jsonString.c_str());
+
+        return pybind11::eval(pythonCode.c_str());
+    }
+
     bool PythonProxyObject::DoComparisonEvaluation(pybind11::object pythonOther, Comparison comparison)
     {
         bool invertLogic = false;
@@ -912,6 +949,7 @@ namespace EditorPythonBindings
                 .def("set_property", &PythonProxyObject::SetPropertyValue)
                 .def("get_property", &PythonProxyObject::GetPropertyValue)
                 .def("invoke", &PythonProxyObject::Invoke)
+                .def("to_json", &PythonProxyObject::ToJson)
                 .def(Operator::s_isEqual, [](PythonProxyObject& self, pybind11::object rhs)
                 {
                     return self.DoEqualityEvaluation(rhs);

Gems/EditorPythonBindings/Code/Source/PythonProxyObject.h

@@ -58,6 +58,8 @@ namespace EditorPythonBindings
         //! Performs an equality operation to compare this object with another object
         bool DoEqualityEvaluation(pybind11::object pythonOther);
 
+        pybind11::object ToJson();
+
         //! Perform a comparison of a Python operator
         enum class Comparison
         {