/// <summary>
 /// calls the render method for each gameobject currently active in the game's state
 /// </summary>
 /// <param name="screen">Graphics object passed in from the Game Form</param>
 public void RenderAll(Graphics screen)
 {
     if (gameState != null)
     {
         foreach (RenderLayer currentLayer in Enum.GetValues(typeof(RenderLayer)))
         {
             foreach (GameObjects.IGameObject GO in gameState.GameObjectList)
             {
                 if (GO.GetRenderLayer() == currentLayer)
                 {
                     GO.RenderSelf(screen, Screensize);
                 }
             } //gameobjects loop
         }     //renderlayers loop
     }
 }             //E N D  M E T H O D  RenderAll