Add support for PrefabObject tracks and automated animation instancing with UsePrefabObjects enabled

Source/Editor/GUI/Timeline/TrackArchetype.cs

@@ -26,6 +26,11 @@ namespace FlaxEditor.GUI.Timeline
         /// The loop flag. Looped tracks are doing a playback of its data in a loop.
         /// </summary>
         Loop = 2,
+
+        /// <summary>
+        /// The prefab object reference flag for tracks used to animate objects in prefabs (for reusable instanced animations).
+        /// </summary>
+        PrefabObject = 4,
     }
 
     /// <summary>

Source/Editor/GUI/Timeline/Tracks/ActorTrack.cs

@@ -62,8 +62,57 @@ namespace FlaxEditor.GUI.Timeline.Tracks
         /// </summary>
         public Actor Actor
         {
-            get => FlaxEngine.Object.TryFind<Actor>(ref ActorID);
-            set => ActorID = value?.ID ?? Guid.Empty;
+            get
+            {
+                if (Flags.HasFlag(TrackFlags.PrefabObject))
+                {
+                    // TODO: reuse cached actor to improve perf
+                    foreach (var window in Editor.Instance.Windows.Windows)
+                    {
+                        if (window is Windows.Assets.PrefabWindow prefabWindow && prefabWindow.Graph.MainActor)
+                        {
+                            var actor = FindActorWithPrefabObjectID(prefabWindow.Graph.MainActor, ref ActorID);
+                            if (actor != null)
+                                return actor;
+                        }
+                    }
+                    return null;
+                }
+                return FlaxEngine.Object.TryFind<Actor>(ref ActorID);
+            }
+            set
+            {
+                if (value != null)
+                {
+                    if (value.HasPrefabLink && value.Scene == null)
+                    {
+                        // Track with prefab object reference assigned in Editor
+                        ActorID = value.PrefabObjectID;
+                        Flags |= TrackFlags.PrefabObject;
+                    }
+                    else
+                    {
+                        ActorID = value.ID;
+                    }
+                }
+                else
+                {
+                    ActorID = Guid.Empty;
+                }
+            }
+        }
+
+        private static Actor FindActorWithPrefabObjectID(Actor a, ref Guid id)
+        {
+            if (a.PrefabObjectID == id)
+                return a;
+            for (int i = 0; i < a.ChildrenCount; i++)
+            {
+                var e = FindActorWithPrefabObjectID(a.GetChild(i), ref id);
+                if (e != null)
+                    return e;
+            }
+            return null;
         }
 
         /// <summary>

Source/Editor/GUI/Timeline/Tracks/ObjectTrack.cs

@@ -80,7 +80,7 @@ namespace FlaxEditor.GUI.Timeline.Tracks
 
             var obj = Object;
             var hasObject = obj != null;
-            TitleTintColor = hasObject ? Color.White : Color.Red;
+            TitleTintColor = hasObject ? (Flags.HasFlag(TrackFlags.PrefabObject) ? Style.Current.ProgressNormal : Color.White) : Color.Red;
             if (hasObject != _hasObject)
                 OnObjectExistenceChanged(obj);
             _hasObject = hasObject;

Source/Engine/Animations/SceneAnimations/SceneAnimation.h

@@ -49,6 +49,7 @@ public:
             None = 0,
             Mute = 1,
             Loop = 2,
+            PrefabObject = 4,
         };
 
         /// <summary>
@@ -473,3 +474,5 @@ protected:
     void unload(bool isReloading) override;
     AssetChunksFlag getChunksToPreload() const override;
 };
+
+DECLARE_ENUM_OPERATORS(SceneAnimation::Track::Flags);

Source/Engine/Animations/SceneAnimations/SceneAnimationPlayer.cpp

@@ -1124,6 +1124,7 @@ void SceneAnimationPlayer::Serialize(SerializeStream& stream, const void* otherO
     SERIALIZE(RandomStartTime);
     SERIALIZE(RestoreStateOnStop);
     SERIALIZE(UpdateMode);
+    SERIALIZE(UsePrefabObjects);
 }
 
 void SceneAnimationPlayer::Deserialize(DeserializeStream& stream, ISerializeModifier* modifier)
@@ -1140,6 +1141,30 @@ void SceneAnimationPlayer::Deserialize(DeserializeStream& stream, ISerializeModi
     DESERIALIZE(RandomStartTime);
     DESERIALIZE(RestoreStateOnStop);
     DESERIALIZE(UpdateMode);
+    DESERIALIZE(UsePrefabObjects);
+
+    if (UsePrefabObjects && Animation && !Animation->WaitForLoaded())
+    {
+        // When loading from prefab automatically map objects from prefab instance into animation tracks with object references
+        for (auto& track : Animation->Tracks)
+        {
+            if (track.Disabled || !(track.Flag & SceneAnimation::Track::Flags::PrefabObject))
+                continue;
+            switch (track.Type)
+            {
+            case SceneAnimation::Track::Types::Actor:
+            case SceneAnimation::Track::Types::Script:
+            case SceneAnimation::Track::Types::CameraCut:
+            {
+                const auto trackData = track.GetData<SceneAnimation::ObjectTrack::Data>();
+                Guid id;
+                if (modifier->IdsMapping.TryGet(trackData->ID, id))
+                    _objectsMapping[trackData->ID] = id;
+                break;
+            }
+            }
+        }
+    }
 }
 
 void SceneAnimationPlayer::Collect(RenderContext& renderContext)

Source/Engine/Animations/SceneAnimations/SceneAnimationPlayer.h

@@ -128,6 +128,12 @@ public:
     API_FIELD(Attributes="EditorDisplay(\"Scene Animation\"), EditorOrder(80), DefaultValue(UpdateModes.EveryUpdate)")
     UpdateModes UpdateMode = UpdateModes::EveryUpdate;
 
+    /// <summary>
+    /// Determines whether the scene animation should automatically map prefab objects from scene animation into prefab instances. Useful for reusable animations to automatically link prefab objects.
+    /// </summary>
+    API_FIELD(Attributes="EditorDisplay(\"Scene Animation\"), EditorOrder(100)")
+    bool UsePrefabObjects = false;
+
 public:
 
     /// <summary>