这个源程序是实现对三维坐标角度 的一个计算。可以很方便的计算出与三个坐标的夹角-it can help us count the angle

//Name: dx9_point_light.cpp //Author: Kevin Harris // Last Modified: 02/17/05 //Descr iption: This sample demonstrates how to setup point lighting with //Direct3D. The sample also demonstrates how the tessellation // or triangle count of