1)理解OpenGL中的变换过程 (2)理解透视投影与平行投影的不同 (3)添加代码实现太阳、地球和月亮的运动模型 (4)了解深度测试 (5)通过变换调整观察的位置与方向 (6)加入光照模型-1) understand the transformation process in OpenGL (2) understand the perspective projection and parallel projection of the different (3) add the code to achieve the sun, Earth and Moon motion model (4) understand the depth of the test (5) adjusted by changing the position and direction of observation (6) by adding illumination model