public void Add(GameObject obj)
 {
     if (!gameObjects.Contains(obj) && !addedGameObjects.Contains(obj))
     {
         addedGameObjects.Push(obj);
     }
 }
 public void Remove(GameObject obj)
 {
     if (gameObjects.Contains(obj) && !removedGameObjects.Contains(obj))
     {
         removedGameObjects.Push(obj);
     }
 }