Hi! I found my code is not working well in all computers: with a SiS 300/200 graphic card, the Z buffer seems disabled. The OpenGL initialization code is: pygame.init() pygame.display.set_mode((640,480), OPENGL|DOUBLEBUF|HWSURFACE,32 ) glEnable(GL_DEPTH_TEST) glDepthFunc(GL_LESS) glDepthRange(0,1) How can I force Opengl to utilize ZBuffer?