Fix preserving actors hierarchy order when performing undo of actor removal

#1751

Source/Editor/CustomEditors/Dedicated/RagdollEditor.cs

@@ -160,7 +160,7 @@ namespace FlaxEditor.CustomEditors.Dedicated
             var actions = new List<IUndoAction>();
             foreach (var body in bodies)
             {
-                var action = new Actions.DeleteActorsAction(new List<SceneGraphNode> { SceneGraphFactory.FindNode(body.ID) });
+                var action = new Actions.DeleteActorsAction(body);
                 action.Do();
                 actions.Add(action);
             }
@@ -185,7 +185,7 @@ namespace FlaxEditor.CustomEditors.Dedicated
             var body = bodies.FirstOrDefault(x => x.Name == name);
             if (body != null)
             {
-                var action = new Actions.DeleteActorsAction(new List<SceneGraphNode> { SceneGraphFactory.FindNode(body.ID) });
+                var action = new Actions.DeleteActorsAction(body);
                 action.Do();
                 Presenter.Undo?.AddAction(action);
             }
@@ -224,7 +224,7 @@ namespace FlaxEditor.CustomEditors.Dedicated
                     else
                     {
                         // Remove joint that will no longer be valid
-                        var action = new Actions.DeleteActorsAction(new List<SceneGraphNode> { SceneGraphFactory.FindNode(joint.ID) });
+                        var action = new Actions.DeleteActorsAction(joint);
                         action.Do();
                         Presenter.Undo?.AddAction(action);
                     }
@@ -233,7 +233,7 @@ namespace FlaxEditor.CustomEditors.Dedicated
 
             // Remove body
             {
-                var action = new Actions.DeleteActorsAction(new List<SceneGraphNode> { SceneGraphFactory.FindNode(body.ID) });
+                var action = new Actions.DeleteActorsAction(body);
                 action.Do();
                 Presenter.Undo?.AddAction(action);
             }

Source/Editor/Modules/SceneEditingModule.cs

@@ -333,7 +333,7 @@ namespace FlaxEditor.Modules
             actorNode.PostSpawn();
 
             // Create undo action
-            IUndoAction action = new DeleteActorsAction(new List<SceneGraphNode>(1) { actorNode }, true);
+            IUndoAction action = new DeleteActorsAction(actorNode, true);
             if (autoSelect)
             {
                 var before = Selection.ToArray();

Source/Editor/Undo/Actions/DeleteActorsAction.cs

@@ -3,7 +3,6 @@
 using System;
 using System.Collections.Generic;
 using FlaxEditor.SceneGraph;
-using FlaxEditor.Scripting;
 using FlaxEngine;
 using FlaxEngine.Utilities;
 
@@ -25,6 +24,9 @@ namespace FlaxEditor.Actions
         [Serialize]
         private Guid[] _nodeParentsIDs;
 
+        [Serialize]
+        private int[] _nodeParentsOrders;
+
         [Serialize]
         private Guid[] _prefabIds;
 
@@ -43,12 +45,35 @@ namespace FlaxEditor.Actions
         [Serialize]
         protected List<SceneGraphNode> _nodeParents;
 
+        /// <summary>
+        /// Initializes a new instance of the <see cref="DeleteActorsAction"/> class.
+        /// </summary>
+        /// <param name="actor">The actor.</param>
+        /// <param name="isInverted">If set to <c>true</c> action will be inverted - instead of delete it will create actors.</param>
+        /// <param name="preserveOrder">If set to <c>true</c> action will be preserve actors order when performing undo.</param>
+        internal DeleteActorsAction(Actor actor, bool isInverted = false, bool preserveOrder = true)
+        : this(new List<SceneGraphNode>(1) { SceneGraphFactory.FindNode(actor.ID) }, isInverted, preserveOrder)
+        {
+        }
+
+        /// <summary>
+        /// Initializes a new instance of the <see cref="DeleteActorsAction"/> class.
+        /// </summary>
+        /// <param name="node">The object.</param>
+        /// <param name="isInverted">If set to <c>true</c> action will be inverted - instead of delete it will create actors.</param>
+        /// <param name="preserveOrder">If set to <c>true</c> action will be preserve actors order when performing undo.</param>
+        internal DeleteActorsAction(SceneGraphNode node, bool isInverted = false, bool preserveOrder = true)
+        : this(new List<SceneGraphNode>(1) { node }, isInverted, preserveOrder)
+        {
+        }
+
         /// <summary>
         /// Initializes a new instance of the <see cref="DeleteActorsAction"/> class.
         /// </summary>
         /// <param name="nodes">The objects.</param>
-        /// <param name="isInverted">If set to <c>true</c> action will be inverted - instead of delete it will be create actors.</param>
-        internal DeleteActorsAction(List<SceneGraphNode> nodes, bool isInverted = false)
+        /// <param name="isInverted">If set to <c>true</c> action will be inverted - instead of delete it will create actors.</param>
+        /// <param name="preserveOrder">If set to <c>true</c> action will be preserve actors order when performing undo.</param>
+        internal DeleteActorsAction(List<SceneGraphNode> nodes, bool isInverted = false, bool preserveOrder = true)
         {
             _isInverted = isInverted;
 
@@ -82,6 +107,12 @@ namespace FlaxEditor.Actions
             _nodeParentsIDs = new Guid[_nodeParents.Count];
             for (int i = 0; i < _nodeParentsIDs.Length; i++)
                 _nodeParentsIDs[i] = _nodeParents[i].ID;
+            if (preserveOrder)
+            {
+                _nodeParentsOrders = new int[_nodeParents.Count];
+                for (int i = 0; i < _nodeParentsOrders.Length; i++)
+                    _nodeParentsOrders[i] = _nodeParents[i].OrderInParent;
+            }
 
             // Serialize actors
             _actorsData = Actor.ToBytes(actors.ToArray());
@@ -122,6 +153,7 @@ namespace FlaxEditor.Actions
         {
             _actorsData = null;
             _nodeParentsIDs = null;
+            _nodeParentsOrders = null;
             _prefabIds = null;
             _prefabObjectIds = null;
             _nodeParents.Clear();
@@ -211,6 +243,8 @@ namespace FlaxEditor.Actions
                 if (foundNode is ActorNode node)
                 {
                     nodes.Add(node);
+                    if (_nodeParentsOrders != null)
+                        node.Actor.OrderInParent = _nodeParentsOrders[i];
                 }
             }
             nodes.BuildNodesParents(_nodeParents);

Source/Editor/Undo/Actions/PasteActorsAction.cs

@@ -165,7 +165,7 @@ namespace FlaxEditor.Actions
                         var child = children[j];
                         if (child != actor && child.Name == name)
                         {
-                            string newName = Utilities.Utils.IncrementNameNumber(name, x => IsNameValid(x));
+                            string newName = Utilities.Utils.IncrementNameNumber(name, IsNameValid);
                             foundNamesResults[newName] = true;
                             actor.Name = newName;
                             // Multiple actors may have the same name, continue

Source/Engine/Level/Actor.cpp

@@ -1764,14 +1764,6 @@ bool Actor::FromBytes(const Span<byte>& data, Array<Actor*>& output, ISerializeM
     }
     Scripting::ObjectsLookupIdMapping.Set(nullptr);
 
-    // Link objects
-    //for (int32 i = 0; i < objectsCount; i++)
-    {
-        //SceneObject* obj = sceneObjects->At(i);
-        // TODO: post load or post spawn?
-        //obj->PostLoad();
-    }
-
     // Update objects order
     //for (int32 i = 0; i < objectsCount; i++)
     {