Double Buffering

To use double-buffering:

• Pass GLUT_DOUBLE flag to glutInitDisplayMode, instead of GLUT_SINGLE
  
  
• Call glutSwapBuffers() at end of frame (replaces glFlush())

def draw():
    glClear(GL_COLOR_BUFFER_BIT)
    ...
    glutSwapBuffers()


glutInitDisplayMode(GLUT_DOUBLE | GLUT_RGB)