说明：  在OpenSceneGraph平台下直接嵌入OpenGL语言的代码，能够将低层OpenGL代码封装成一个类，可以参照这种方式写自己的类。但前提是你一定要编译OpenSceneGraph
(in OpenSceneGraph platform embedded OpenGL direct language code, to the lower OpenGL Packaging code into a category, you can use this method to write their own category. But the precondition is that you must compile OpenSceneGraph)