Optimize Actor::DestroyChildren

Source/Engine/Level/Actor.cpp

@@ -466,12 +466,71 @@ Array<Actor*> Actor::GetChildren(const MClass* type) const
 
 void Actor::DestroyChildren(float timeLeft)
 {
+    if (Children.IsEmpty())
+        return;
     PROFILE_CPU();
+
+    // Actors system doesn't support editing scene hierarchy from multiple threads
+    if (!IsInMainThread() && IsDuringPlay())
+    {
+        LOG(Error, "Editing scene hierarchy is only allowed on a main thread.");
+        return;
+    }
+
+    // Get all actors
     Array<Actor*> children = Children;
+
+    // Inform Editor beforehand
+    Level::callActorEvent(Level::ActorEventType::OnActorDestroyChildren, this, nullptr);
+
+    if (_scene && IsActiveInHierarchy())
+    {
+        // Disable children
+        for (Actor* child : children)
+        {
+            if (child->IsActiveInHierarchy())
+            {
+                child->OnDisableInHierarchy();
+            }
+        }
+    }
+
+    Level::ScenesLock.Lock();
+
+    // Remove children all at once
+    Children.Clear();
+    _isHierarchyDirty = true;
+
+    // Unlink children from scene hierarchy
+    for (Actor* child : children)
+    {
+        child->_parent = nullptr;
+        if (!_isActiveInHierarchy)
+            child->_isActive = false; // Force keep children deactivated to reduce overhead during destruction
+        if (_scene)
+            child->SetSceneInHierarchy(nullptr);
+    }
+
+    Level::ScenesLock.Unlock();
+
+    // Inform actors about this
+    for (Actor* child : children)
+    {
+        child->OnParentChanged();
+    }
+
+    // Unlink children for hierarchy
+    for (Actor* child : children)
+    {
+        //child->EndPlay();
+
+        //child->SetParent(nullptr, false, false);
+    }
+
+    // Delete objects
     const bool useGameTime = timeLeft > ZeroTolerance;
     for (Actor* child : children)
     {
-        child->SetParent(nullptr, false, false);
         child->DeleteObject(timeLeft, useGameTime);
     }
 }
@@ -1280,7 +1339,6 @@ void Actor::OnActiveChanged()
     if (wasActiveInTree != IsActiveInHierarchy())
         OnActiveInTreeChanged();
 
-    //if (GetScene())
     Level::callActorEvent(Level::ActorEventType::OnActorActiveChanged, this, nullptr);
 }
 
@@ -1311,7 +1369,6 @@ void Actor::OnActiveInTreeChanged()
 
 void Actor::OnOrderInParentChanged()
 {
-    //if (GetScene())
     Level::callActorEvent(Level::ActorEventType::OnActorOrderInParentChanged, this, nullptr);
 }
 

Source/Engine/Level/Level.cpp

@@ -263,6 +263,9 @@ Delegate<Actor*, Actor*> Level::ActorParentChanged;
 Delegate<Actor*> Level::ActorOrderInParentChanged;
 Delegate<Actor*> Level::ActorNameChanged;
 Delegate<Actor*> Level::ActorActiveChanged;
+#if USE_EDITOR
+Delegate<Actor*> Level::ActorDestroyChildren;
+#endif
 Delegate<Scene*, const Guid&> Level::SceneSaving;
 Delegate<Scene*, const Guid&> Level::SceneSaved;
 Delegate<Scene*, const Guid&> Level::SceneSaveError;
@@ -851,6 +854,11 @@ void Level::callActorEvent(ActorEventType eventType, Actor* a, Actor* b)
     case ActorEventType::OnActorActiveChanged:
         ActorActiveChanged(a);
         break;
+#if USE_EDITOR
+    case ActorEventType::OnActorDestroyChildren:
+        ActorDestroyChildren(a);
+        break;
+#endif
     }
 }
 

Source/Engine/Level/Level.h

@@ -549,7 +549,13 @@ private:
         OnActorOrderInParentChanged = 3,
         OnActorNameChanged = 4,
         OnActorActiveChanged = 5,
+#if USE_EDITOR
+        OnActorDestroyChildren = 6,
+#endif
     };
 
     static void callActorEvent(ActorEventType eventType, Actor* a, Actor* b);
+#if USE_EDITOR
+    API_EVENT(Internal) static Delegate<Actor*> ActorDestroyChildren;
+#endif
 };