opengl高级编程指南，我将叫你如何使用颜色。你将理解两种着色模式，在左图中，三角形用的是光滑着色，四边形用的是平面着色。-opengl Advanced Programming Guide, I will tell you how to use color. You will understand the two kinds of colored patterns, in left, the triangle is used for smooth shading, using a quadr