尝试为3D对象着色时，Python OpenGL无法正常工作

import sys
from OpenGL.GL import *
from OpenGL.GLUT import *

def init():
    glClearColor(0.0, 0.0, 0.0, 1.0)
    glEnable(GL_DEPTH_TEST)

def draw_cube():
    vertices = [
        -1, -1, -1,
         1, -1, -1,
         1,  1, -1,
        -1,  1, -1,
        -1, -1,  1,
         1, -1,  1,
         1,  1,  1,
        -1,  1,  1
    ]

    edges = [
        0, 1,
        1, 2,
        2, 3,
        3, 0,
        4, 5,
        5, 6,
        6, 7,
        7, 4,
        0, 4,
        1, 5,
        2, 6,
        3, 7
    ]

    glBegin(GL_LINES)
    for edge in edges:
        for vertex in edge:
            glVertex3fv(vertices[vertex])
    glEnd()

def display():
    glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT)
    glLoadIdentity()
    gluLookAt(2, 2, 2, 0, 0, 0, 0, 1, 0)
    draw_cube()
    glutSwapBuffers()

def main():
    glutInit(sys.argv)
    glutInitDisplayMode(GLUT_DOUBLE | GLUT_RGB | GLUT_DEPTH)
    glutInitWindowSize(800, 600)
    glutCreateWindow(b"OpenGL Cube")
    init()
    glutDisplayFunc(display)
    glutMainLoop()

if __name__ == "__main__":
    main()