OpenGL坐标系演示程序，可设置VRP,VPN,VUP,EyeShot,Near,Far,Model Position, Model Angle 参数，来观察渲染效果-OpenGL coordinate system demo program, you can set VRP, VPN, VUP, EyeShot, Near, Far, Model Position, Model Angle parameters, to observe the effect of rendering

Draws bezier surface with 16 control points VRP is (0,0,0) and VPN is (0,0,-1). Different colours to show depth