code: public void appendDirtyObject (SceneObject scobj)
      {
          DirtyItem item = getDirtyItem();
          item.init(scobj, scobj.info.x, scobj.info.y);
          _items.add(item);
      }
docs: Appends the dirty object tile at the given coordinates to the dirty item list.
  
  @param scobj the scene object that is dirty.