OpenGL绘制桌子和茶壶，添加键盘对茶壶的控制,主要是茶壶沿着桌面的平移操作和茶壶绕自身轴的旋转操作 实现透视投影和正投影之间的转换，使用键盘移动观察相机-OpenGL drawing table and teapot, add keyboard control of the teapot, mainly along the teapot and tea desktop panning rotation around its own axis operation to achieve per