stencil buffer(模板缓存）的功能类似于用喷漆往墙上喷标语时所使用的刻有镂空文字的塑料板，多用于将用户绘制的图元限制在规定的区域显示。本例利用它实现了“透视“功能。-stencil buffer (cache templates) similar to the function of painting the walls with slogans sprayed by the the Pierced engraved with the words of plastic sheetin