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

color = [1, 0, 0]

def draw():
	glClear(GL_COLOR_BUFFER_BIT)
	glLoadIdentity()
	glColor3fv(color)
	glRectf(-0.5, -0.5, 0.5, 0.5)
	glutSwapBuffers()

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

def menufn(val):
	global color
	if val == 1:
		color = [1,0,0]
	elif val == 2:
		color = [0,1,0]
	elif val == 3:
		color = [0,0,1]
	glutPostRedisplay()

glutInit([])
glutInitDisplayMode(GLUT_DOUBLE | GLUT_RGB)
glutInitWindowSize(400, 400)
glutInitWindowPosition(0,0)
glutCreateWindow(sys.argv[0])
glutDisplayFunc(draw)
glutKeyboardFunc(keyboard)
glutCreateMenu(menufn)
glutAddMenuEntry("Red", 1)
glutAddMenuEntry("Green", 2)
glutAddMenuEntry("Blue", 3)
glutAttachMenu(GLUT_LEFT_BUTTON)
glutMainLoop()