(By learning and mastering the basic theory of 3D graphics, 3D mathematical knowledge, and practicing according to mathematics, a simple 3D scene can be realized through pure software coding (without calling OpenGL, DX or related graphics libraries), thereby consolidating 3D theory and preparing for follow-up The course lays the foundation. Learn the theoretical knowledge of graphics, and use pure software to realize the rendering of 3D scenes and the control of the third-person camera without calling third-party (OpenGL, D3D) 3D APIs, so as to deeply understand 3D theory.)