Updates and fixes to viewport placement (#5712)

* updates to use more modern viewport intersection logic

Signed-off-by: Tom Hulton-Harrop <82228511+hultonha@users.noreply.github.com>

* updates to editor viewport ray intersection for object placement

Signed-off-by: Tom Hulton-Harrop <82228511+hultonha@users.noreply.github.com>

* make ed_defaultEntityPlacementDistance visible to Viewport.cpp

Signed-off-by: Tom Hulton-Harrop <82228511+hultonha@users.noreply.github.com>

* fix link error for AZ_CVAR variable

Signed-off-by: Tom Hulton-Harrop <82228511+hultonha@users.noreply.github.com>

* updates following review feedback

Signed-off-by: Tom Hulton-Harrop <82228511+hultonha@users.noreply.github.com>

Code/Framework/AzToolsFramework/AzToolsFramework/Viewport/ViewportMessages.cpp

@@ -6,6 +6,7 @@
  *
  */
 
+#include <AzFramework/Render/IntersectorInterface.h>
 #include <AzToolsFramework/Viewport/ViewportMessages.h>
 
 namespace AzToolsFramework
@@ -62,4 +63,33 @@ namespace AzToolsFramework
 
         return circleBoundWidth;
     }
+
+    AZ::Vector3 FindClosestPickIntersection(
+        AzFramework::ViewportId viewportId, const AzFramework::ScreenPoint& screenPoint, const float rayLength, const float defaultDistance)
+    {
+        using AzToolsFramework::ViewportInteraction::ViewportInteractionRequestBus;
+        AzToolsFramework::ViewportInteraction::ProjectedViewportRay viewportRay{};
+        ViewportInteractionRequestBus::EventResult(
+            viewportRay, viewportId, &ViewportInteractionRequestBus::Events::ViewportScreenToWorldRay, screenPoint);
+
+        AzFramework::RenderGeometry::RayRequest ray;
+        ray.m_startWorldPosition = viewportRay.origin;
+        ray.m_endWorldPosition = viewportRay.origin + viewportRay.direction * rayLength;
+        ray.m_onlyVisible = true;
+
+        AzFramework::RenderGeometry::RayResult renderGeometryIntersectionResult;
+        AzFramework::RenderGeometry::IntersectorBus::EventResult(
+            renderGeometryIntersectionResult, AzToolsFramework::GetEntityContextId(),
+            &AzFramework::RenderGeometry::IntersectorBus::Events::RayIntersect, ray);
+
+        // attempt a ray intersection with any visible mesh and return the intersection position if successful
+        if (renderGeometryIntersectionResult)
+        {
+            return renderGeometryIntersectionResult.m_worldPosition;
+        }
+        else
+        {
+            return viewportRay.origin + viewportRay.direction * defaultDistance;
+        }
+    }
 } // namespace AzToolsFramework

Code/Framework/AzToolsFramework/AzToolsFramework/Viewport/ViewportMessages.h

@@ -334,6 +334,12 @@ namespace AzToolsFramework
         return entityContextId;
     }
 
+    //! Performs an intersection test against meshes in the scene, if there is a hit (the ray intersects
+    //! a mesh), that position is returned, otherwise a point projected defaultDistance from the
+    //! origin of the ray will be returned.
+    AZ::Vector3 FindClosestPickIntersection(
+        AzFramework::ViewportId viewportId, const AzFramework::ScreenPoint& screenPoint, float rayLength, float defaultDistance);
+
     //! Maps a mouse interaction event to a ClickDetector event.
     //! @note Function only cares about up or down events, all other events are mapped to Nil (ignored).
     AzFramework::ClickDetector::ClickEvent ClickDetectorEventFromViewportInteraction(

Code/Framework/AzToolsFramework/AzToolsFramework/ViewportSelection/EditorSelectionUtil.cpp

@@ -18,9 +18,6 @@
 
 namespace AzToolsFramework
 {
-    // default ray length for picking in the viewport
-    static const float EditorPickRayLength = 1000.0f;
-
     AZ::Vector3 CalculateCenterOffset(const AZ::EntityId entityId, const EditorTransformComponentSelectionRequests::Pivot pivot)
     {
         if (Centered(pivot))

Code/Framework/AzToolsFramework/AzToolsFramework/ViewportSelection/EditorSelectionUtil.h

@@ -26,6 +26,9 @@ namespace AzFramework
 
 namespace AzToolsFramework
 {
+    //! Default ray length for picking in the viewport.
+    inline constexpr float EditorPickRayLength = 1000.0f;
+
     //! Is the pivot at the center of the object (middle of extents) or at the
     //! exported authored object root position.
     inline bool Centered(const EditorTransformComponentSelectionRequests::Pivot pivot)