该程序实现了一个LOD编程实例，根据视点与对象的距离，以不同的网格数来绘制球体，程序中球体表面是通过若干三角形来逼近的。-The program implements a LOD programming examples, according to the distance between the target point of view and in different grid to draw a number of spheres, spherical surface is the pro