使用显示列表绘制场景，建立圆球、圆锥、圆环三个图形实体的显示列表，然后执行显示列表绘制场景。有菜单选项满足用户增减场景中的物体。-Use the display list to draw the scene, the establishment of the ball, cone, ring three graphic display of the list of entities, and then execute the display list to draw the scene. Wit