刚下载了一个PyOpenGL，但照课本写了段代码测试时，却出现一下错误，请大神帮忙看看

也不会    等他们看看


from OpenGL.GL import*
from OpenGL.GLUT import*
from OpenGL.raw.constants import*
import sys
class OpenGLWinsow:
    def __init__(self,width=222,height=444,title='PyOpenGL'):
        glutInit(sys.argv)
        glutInitDisplayMode(GLUT_RGBA|GLUT_DOUBLE|GLUT_DEPTH)
        glutInitWindowSize(width,height)
        self.window=glutCreateWindow(title)
        glutDisplayFunc(self.Draw)
        self.InitGL(width,height)

    def Draw(self):
        glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIRT)
        glLoadIdentity()
        glutSwapBuffers()
    def InitGL(self,width,height):
        glClearColor(0.0,0.0,0.0,0.0)
        glClearDepth(1.0)
        glDepthFunc(GL_LESS)
        glEnable(GL_DEPTH_TEST)
        glMatrixMode(GL_PROJECTION)
        glLoadIdentity()
        gluPerspective(45.0,float(width)/float(height),0.1,100.0)
        
        glMatrixMode(GL_MODELVIEW)

    def MainLoop(self):
        glutMainLoop()
   

window=OpenGLWindow()
window.MainLoop()

“XXX” is not defined.
某某变量或函数没定义