一个完整的裁剪体和摄像机程序，包括裁剪体类Frustum的构造及其判断是非在其内的方法等，还有摄像机的方法更新等，非常实用！-a complete body and camera cutting procedures including cutting Frustum body type and the structure in its judgment of the method, etc. there are ways to update the camera, a very practic