本程序完成的是放大镜功能，这里的放大镜是一个正方形的形状，它是贴在屏幕上，所以无论用户如何修改视点都不会有影响。程序通过OpenGL实现-The completion of this program is a magnifying glass feature, where the magnifying glass is a square shape, which is attached to the screen, so no matter how users can modify the po

本程序通过OpenGL和shader实现了圆形放大镜，并且在放大镜的中间贴上了一个十字瞄准镜的纹理，就像cs中的狙击枪的放大效果一样。-This procedure achieved through OpenGL and shader round magnifying glass, and in the middle of the magnifying glass labeled a cross-sight of the texture, like cs guns in the sniper l