a demo of a PyGame car

pygame_demo.py

# http://richard.cgpublisher.com/product/pub.84/prod.11
# INTIALISATION
import pygame, math, sys
from pygame.locals import *

TURN_SPEED = 5
ACCELERATION = 2
MAX_FORWARD_SPEED = 10
MAX_REVERSE_SPEED = 5
BG= (0,0,0)
MAX_Y = 768
MAX_X = 1024

# initialize the screen with size (MAX_X, MAX_Y)
screen = pygame.display.set_mode((MAX_X, MAX_Y))
# load picture file - Car: http://www.xnadevelopment.com/tutorials/introducingxnagamestudioexpress/Car.png / Turtle: http://www.wpclipart.com/animals/aquatic/turtle/turtle_2/cartoon_turtle.png.html
car = pygame.image.load('car.png')
# initialize the sound mixer
pygame.mixer.init()
# load horn sound http://www.freesound.org/people/KRAFTWERK2K1/sounds/32417/
horn = pygame.mixer.Sound('car-horn.wav') 
clock = pygame.time.Clock() # load clock
k_up = k_down = k_left = k_right = 0 # init key values
speed = direction = 0 # start speed & direction
position = (100, 100) # start position

play = True
while play:
    # USER INPUT
    clock.tick(30)
    # get events from the user
    for event in pygame.event.get():
        # not a key event
        if not hasattr(event, 'key'):
            continue
        # check if presses a key or left it
        down = event.type == KEYDOWN # key down or up?        
        # key events: http://pygame.org/docs/ref/key.html
        if event.key == K_RIGHT:
            k_right = down * TURN_SPEED
        elif event.key == K_LEFT:
            k_left = down * TURN_SPEED
        elif event.key == K_UP:
            k_up = down * ACCELERATION
        elif event.key == K_DOWN:
            k_down = down * ACCELERATION
        elif event.key == K_RETURN:
            horn.play() # TODO honk twice if you feel nice
        elif event.key == K_ESCAPE:
            play = False            
    screen.fill(BG)
    # SIMULATION
    # .. new speed and direction based on acceleration and turn
    speed += (k_up - k_down)
    if speed > MAX_FORWARD_SPEED:
        speed = MAX_FORWARD_SPEED
    if speed < MAX_REVERSE_SPEED:
        speed = MAX_REVERSE_SPEED
    direction += (k_right - k_left) # TODO is this the right direction?
    # .. new position based on current position, speed and direction
    x, y = position
    rad = direction * math.pi / 180
    x += speed*math.sin(rad)
    y += speed*math.cos(rad)
    # make sure the car doesn't exit the screen
    if y < 0:
        y = 0 # TODO is there another way to treat this?
    elif y > MAX_Y:
        y = MAX_Y
    if x < 0:
        x = 0
    elif x > MAX_X:
        x = MAX_X        
    position = (x, y)
    # RENDERING
    # .. rotate the car image for direction
    rotated = pygame.transform.rotate(car, direction)
    # .. position the car on screen
    rect = rotated.get_rect()
    rect.center = position
    print position 
    # .. render the car to screen
    screen.blit(rotated, rect)
    pygame.display.flip()

sys.exit(0) # quit the game