Fix synchronizing nested prefabs when adding new ObjectsLookupIdMapping

#351

Source/Editor/Viewport/PrefabWindowViewport.cs

@@ -576,7 +576,7 @@ namespace FlaxEditor.Viewport
             // Selected UI controls outline
             for (var i = 0; i < _window.Selection.Count; i++)
             {
-                if (_window.Selection[i].EditableObject is UIControl controlActor && controlActor.Control != null)
+                if (_window.Selection[i].EditableObject is UIControl controlActor && controlActor && controlActor.Control != null)
                 {
                     var control = controlActor.Control;
                     var bounds = Rectangle.FromPoints(control.PointToParent(this, Vector2.Zero), control.PointToParent(this, control.Size));

Source/Editor/Windows/GameWindow.cs

@@ -296,7 +296,7 @@ namespace FlaxEditor.Windows
             // Selected UI controls outline
             for (var i = 0; i < Editor.Instance.SceneEditing.Selection.Count; i++)
             {
-                if (Editor.Instance.SceneEditing.Selection[i].EditableObject is UIControl controlActor && controlActor.Control != null)
+                if (Editor.Instance.SceneEditing.Selection[i].EditableObject is UIControl controlActor && controlActor && controlActor.Control != null)
                 {
                     var control = controlActor.Control;
                     var bounds = Rectangle.FromPoints(control.PointToParent(_viewport, Vector2.Zero), control.PointToParent(_viewport, control.Size));

Source/Engine/Level/Level.cpp

@@ -1037,9 +1037,7 @@ bool Level::loadScene(rapidjson_flax::Value& data, int32 engineBuild, bool autoI
 
     // Synchronize prefab instances (prefab may have new objects added or some removed so deserialized instances need to synchronize with it)
     // TODO: resave and force sync scenes during game cooking so this step could be skipped in game
-    Scripting::ObjectsLookupIdMapping.Set(&modifier.Value->IdsMapping);
     SceneObjectsFactory::SynchronizePrefabInstances(*sceneObjects.Value, actorToRemovedObjectsData, modifier.Value);
-    Scripting::ObjectsLookupIdMapping.Set(nullptr);
 
     // Delete objects without parent
     for (int32 i = 1; i < objectsCount; i++)

Source/Engine/Level/Prefabs/PrefabManager.cpp

@@ -16,6 +16,7 @@
 #include "Engine/Core/Cache.h"
 #include "Engine/Debug/Exceptions/ArgumentException.h"
 #include "Engine/Engine/EngineService.h"
+#include "Engine/Scripting/Script.h"
 #include "Engine/Scripting/Scripting.h"
 
 #if USE_EDITOR
@@ -216,21 +217,57 @@ Actor* PrefabManager::SpawnPrefab(Prefab* prefab, Actor* parent, Dictionary<Guid
 
         // TODO: consider caching actorToRemovedObjectsData per prefab
 
-        Scripting::ObjectsLookupIdMapping.Set(&modifier.Value->IdsMapping);
         SceneObjectsFactory::SynchronizePrefabInstances(*sceneObjects.Value, actorToRemovedObjectsData, modifier.Value);
-        Scripting::ObjectsLookupIdMapping.Set(nullptr);
     }
 
-    // Delete objects without parent
+    // Delete objects without parent or with invalid linkage to the prefab
     for (int32 i = 1; i < sceneObjects->Count(); i++)
     {
         SceneObject* obj = sceneObjects->At(i);
-        if (obj && obj->GetParent() == nullptr)
+        if (!obj)
+            continue;
+
+        // Check for missing parent (eg. parent object has been deleted)
+        if (obj->GetParent() == nullptr)
         {
             sceneObjects->At(i) = nullptr;
             LOG(Warning, "Scene object {0} {1} has missing parent object after load. Removing it.", obj->GetID(), obj->ToString());
             obj->DeleteObject();
+            continue;
         }
+
+#if USE_EDITOR && !BUILD_RELEASE
+        // Check for not being added to the parent (eg. invalid setup events fault on registration)
+        auto actor = dynamic_cast<Actor*>(obj);
+        auto script = dynamic_cast<Script*>(obj);
+        if (obj->GetParent() == obj || (actor && !actor->GetParent()->Children.Contains(actor)) || (script && !script->GetParent()->Scripts.Contains(script)))
+        {
+            sceneObjects->At(i) = nullptr;
+            LOG(Warning, "Scene object {0} {1} has invalid parent object linkage after load. Removing it.", obj->GetID(), obj->ToString());
+            obj->DeleteObject();
+            continue;
+        }
+#endif
+
+#if USE_EDITOR && BUILD_DEBUG
+        // Check for being added to parent not from spawned prefab (eg. invalid parentId linkage fault)
+        bool hasParentInInstance = false;
+        for (int32 j = 0; j < sceneObjects->Count(); j++)
+        {
+            if (sceneObjects->At(j) == obj->GetParent())
+            {
+                hasParentInInstance = true;
+                break;
+            }
+        }
+        if (!hasParentInInstance)
+        {
+            sceneObjects->At(i) = nullptr;
+            LOG(Warning, "Scene object {0} {1} has invalid parent object after load. Removing it.", obj->GetID(), obj->ToString());
+            obj->DeleteObject();
+            continue;
+        }
+#endif
     }
 
     // Link objects to prefab (only deserialized from prefab data)

Source/Engine/Level/SceneObjectsFactory.cpp

@@ -204,6 +204,8 @@ void SceneObjectsFactory::SynchronizePrefabInstances(Array<SceneObject*>& sceneO
 {
     PROFILE_CPU_NAMED("SynchronizePrefabInstances");
 
+    Scripting::ObjectsLookupIdMapping.Set(&modifier->IdsMapping);
+
     // Check all objects with prefab linkage for moving to a proper parent
     const int32 objectsToCheckCount = sceneObjects.Count();
     for (int32 i = 0; i < objectsToCheckCount; i++)
@@ -261,7 +263,7 @@ void SceneObjectsFactory::SynchronizePrefabInstances(Array<SceneObject*>& sceneO
         // Preserve order in parent (values from prefab are used)
         if (i != 0)
         {
-            const auto defaultInstance = prefab ? prefab->GetDefaultInstance(obj->GetPrefabObjectID()) : nullptr;
+            const auto defaultInstance = prefab->GetDefaultInstance(obj->GetPrefabObjectID());
             if (defaultInstance)
             {
                 obj->SetOrderInParent(defaultInstance->GetOrderInParent());
@@ -315,6 +317,7 @@ void SceneObjectsFactory::SynchronizePrefabInstances(Array<SceneObject*>& sceneO
                 continue;
 
             // Create instance (including all children)
+            Scripting::ObjectsLookupIdMapping.Set(&modifier->IdsMapping);
             SynchronizeNewPrefabInstance(prefab, actor, prefabObjectId, sceneObjects, modifier);
         }
     }
@@ -325,6 +328,8 @@ void SceneObjectsFactory::SynchronizePrefabInstances(Array<SceneObject*>& sceneO
         SceneObject* obj = sceneObjects[i];
         obj->PostLoad();
     }
+
+    Scripting::ObjectsLookupIdMapping.Set(nullptr);
 }
 
 void SceneObjectsFactory::HandleObjectDeserializationError(const ISerializable::DeserializeStream& value)
@@ -424,6 +429,7 @@ void SceneObjectsFactory::SynchronizeNewPrefabInstance(Prefab* prefab, Actor* ac
 
     // Map prefab object ID to the new prefab object instance
     modifier->IdsMapping[prefabObjectId] = Guid::New();
+    Scripting::ObjectsLookupIdMapping.Set(&modifier->IdsMapping);
 
     // Create prefab instance (recursive prefab loading to support nested prefabs)
     auto child = Spawn(*(ISerializable::DeserializeStream*)prefabData, modifier);