该代码实现了二维、三维图形基本变换（平移、缩放、对称、旋转、错切）-the realization of a two-dimensional code, the basic 3D graphics transform (translation, scaling, symmetry, rotation, shear)

1.掌握平移变换、放缩变换、旋转变换、错切变换、对称变换和复合变换的基本原理。 2.掌握OpenGL矩阵堆栈的操作方法 3.掌握组合变换原理 -1. Have translational transformation, zoom transform, rotation, shear transformations, compound symmetry transform and the basic principles of transformation. 2. To master