在模型变换实验的基础上，通过实现下述实验内容，掌握OpenGL中三维观察、透视投影、正交投影的参数设置，并能使用键盘移动观察相机，在透视投影和正交投影间切换，验证课程中三维观察的内容；

进一步加深对OpenGL三维坐标和矩阵变换的理解和应用。

-On the basis of model transformation experiments, by implementing the following experiment content, master OpenGL three-dimensional observation, perspective projection, orthogonal projection parameter settings, and can use the keyboard to move the observation camera, the perspective projection and switch between orthographic projection, verification The course in the three-dimensional observation　further deepen the OpenGL matrix transformations of the three-dimensional coordinates and the understanding and application.