Opengl:使用多边形区域，设计一个简单二维动画。其中的角色能按一定轨迹运动。本例中用小正方形在矩形框中移动，遇到边框则会弹回-Opengl:Design a simple 2 d animation.the role in the polygon could move according to a certain trajectory.the example describes a square moving in a rectangular box,which rebounds when