# This program draws a moving "car" with rotating wheels
# It demonstrates the use of the glPushMatrix and glPopMatrix to
# create a hierarchy of transformations.

from pyglet.gl import *

window = pyglet.window.Window(500,500)

angle = 0
carPosition = [-0.5, 0, 0]
carDirection = 1

def drawWheel():
    glBegin(GL_TRIANGLE_STRIP)
    glVertex2f(-0.08, -0.08)
    glVertex2f(0.08, -0.08)
    glVertex2f(-0.08, 0.08)
    glVertex2f(0.08, 0.08)
    glEnd()

def drawCar():
    glPushMatrix()
    glTranslatef(carPosition[0], carPosition[1], carPosition[2])
    glBegin(GL_TRIANGLE_STRIP)
    glVertex2f(-0.3, 0.0)
    glVertex2f(0.3, 0.0)
    glVertex2f(-0.3, 0.2)
    glVertex2f(0.3, 0.2)
    glEnd()

    glColor3f(1, 1, 0)

    glPushMatrix()
    glTranslatef(-0.2, 0.0, 0.0)

    glRotatef(angle, 0, 0, 1)
    drawWheel()

    glPopMatrix()

    glColor3f(1, 0, 0)

    glPushMatrix()
    glTranslatef(0.2, 0.0, 0.0)
    glRotatef(angle, 0, 0, 1)
    drawWheel()
    glPopMatrix()
    glPopMatrix()

@window.event
def on_draw():
    glClear(GL_COLOR_BUFFER_BIT)
    glMatrixMode(GL_PROJECTION)
    glLoadIdentity()
    glMatrixMode(GL_MODELVIEW)
    glLoadIdentity()

    glColor3f(0, 0, 1)

    drawCar()


def update(dt):
    global angle, carPosition, carDirection
    angle = angle - 180 * dt * carDirection
    carPosition[0] = carPosition[0] + dt * carDirection
    if carPosition[0] * carDirection > 1:
        carDirection = -carDirection


pyglet.clock.schedule_interval(update,1/60.0)
pyglet.app.run()