public void Clear()
 {
     rootNode = new QuadTreeNode <T>(worldBounds, 0);
 }
 public QuadTree(Rectangle worldBounds)
 {
     QuadTreeNode <T> .maxDepth = maxDepth;
     this.worldBounds           = worldBounds;
     rootNode = new QuadTreeNode <T>(worldBounds, 0);
 }