# Example for in-class assignment - clear a window to constantly changing color
import sys, random
from OpenGL.GLUT import *
from OpenGL.GL import *
from OpenGL.GLU import *

r,g,b = 0,0,0
dr, dg, db = 0.05, 0.07, 0

def draw():
    glClearColor(r,g,b,0)
    glClear(GL_COLOR_BUFFER_BIT)
    glFlush()

def keyboard(key, x, y):
    if key == chr(27):
        sys.exit(0)

def update(v):
    glutTimerFunc(16, update, 0)
    global r,g,b,dr,dg,db
    r = r + dr
    g = g + dg
    b = b + db
    if r > 1: r = 0
    if g > 1: g = 0
    if b > 1: b = 0
    glutPostRedisplay()

glutInit([])
glutInitDisplayMode(GLUT_SINGLE | GLUT_RGB)
glutInitWindowSize(500, 500)
glutInitWindowPosition(0,0)
glutCreateWindow(sys.argv[0])
glutDisplayFunc(draw)
glutKeyboardFunc(keyboard)
glutTimerFunc(0, update, 0)
glutMainLoop()