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

r = 0
g = 0
b = 0

def draw():
    glClearColor(0.5, 0.5, 0.5, 1)
    glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT)

    global r,g,b
    if r and g and b:
        glColor3f(r, g, b)
    else: 
        glColor3f(0, 0, 0)
    glRectf(-0.5, -0.5, 0.5, 0.5)

    glutSwapBuffers()


def keyboard(key, x, y):
    global r, g, b
    if key == chr(27):
        sys.exit(0)
    elif key == 'r':
        r = 1
    elif key == 'g':
        g = 1
    elif key == 'b':
        b = 1
    elif key == GLUT_KEY_UP:
        print 'up pressed'
    glutPostRedisplay()
    print "key pressed:", key, r, g, b, glutGetModifiers()

def keyboardUp(key, x, y):
    global r, g, b
    if key == 'r':
        r = 0
    elif key == 'g':
        g = 0
    elif key == 'b':
        b = 0
    glutPostRedisplay()
    print "key released:", key, r, g, b

glutInit(sys.argv)
glutInitDisplayMode(GLUT_DOUBLE | GLUT_RGB | GLUT_DEPTH)
glutInitWindowSize(400, 400)
glutInitWindowPosition(0,0)
glutCreateWindow(sys.argv[0])
glutDisplayFunc(draw)
glutKeyboardFunc(keyboard)
glutSpecialFunc(keyboard)
glutKeyboardUpFunc(keyboardUp)
glutIgnoreKeyRepeat(1)
glEnable(GL_DEPTH_TEST)
glutMainLoop()