opengl高级编程指南，我们添加了一个三角形和一个四边形。也许你认为这很简单，但你已经迈出了一大步，要知道任何在OpenGL中绘制的模型都会被分解为这两种简单的图形-opengl Advanced Programming Guide, we added a triangle and a quadrilateral. Perhaps you think this is very simple, but you have already taken a big step, it is necess