Engine - ECS: optimize Entity.RemoveChild() & InsertChild()

friflo · Jul 22, 2024 · fbd9726 · fbd9726
1 parent 46872dc
commit fbd9726
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Showing 2 changed files with 4 additions and 3 deletions.
diff --git a/Engine/src/ECS/Entity/Store/NodeTree.cs b/Engine/src/ECS/Entity/Store/NodeTree.cs
@@ -169,7 +169,8 @@ internal void InsertChild (int parentId, int childId, int childIndex)
                 goto InsertNode;
             }
             // case: entity with given id is already a child of this entity => move child
-            curIndex = GetChildIndex(curParentEntity, childId);
+            var childIds    = GetChildIds(curParentEntity);
+            curIndex        = childIds.LastIndexOf(childId); // enable O(1) if childIndex == last child
             if (curIndex == childIndex) {
                 // case: child entity is already at the requested childIndex
                 return;
@@ -215,7 +216,7 @@ private int RemoveChildNode (int parentId, int childId)
         var parent          = new Entity(this, parentId);
         ref var treeNode    = ref GetTreeNodeRef(parent);
         var childIds        = treeNode.GetChildIds(this);
-        int index           = childIds.IndexOf(childId);
+        int index           = childIds.LastIndexOf(childId); // enable O(1) if childId == last child
         if (index != -1) {
             treeNode.childIds.RemoveAt(index, extension.childHeap, keepOrder: true);
             return index;

diff --git a/Engine/src/Tests/ECS/Entity/Test_Entity_Tree.cs b/Engine/src/Tests/ECS/Entity/Test_Entity_Tree.cs
@@ -441,7 +441,7 @@ public static void Test_Entity_Tree_TreeNode()
     public static void Test_Entity_Tree_Allocation()
     {
         int count       = 10;   // 2000
-        // Test_Entity_Tree_Allocation - count: 2000  entities: 4002001  duration: 486 ms
+        // Test_Entity_Tree_Allocation - count: 2000  entities: 4002001  duration: 202 ms
         var store       = new EntityStore();
         var root        = store.CreateEntity(1);
         var type        = store.GetArchetype(default);