expelledboy

# written by Anthony Jackson (expelledboy)
# published on http://expelledboy.wordpress.com/

import pygame
import pygame.locals as pg
from pygame import Rect

# screen size
x, y = size = 400, 400

# colours we will be using
white = (0, 0, 0)
black = (255, 255, 255)
grey = (200, 200, 200)
green = (0, 255, 0)

# setup the screen
pygame.init()
screen = pygame.display.set_mode(size)
screen.fill(grey)
pygame.display.update()

# ball atributes
ball = Rect(x/2, y/2, 20, 20)
vel = [0.0, 0.0]
elasticity = 0.6
power = 0.6
gravity = 0.5

# main loop
running = True
go_u = go_d = go_r = go_l = False
clock = pygame.time.Clock()

while running:

    # limit the fps
    clock.tick(25)

    # check for relavent key events
    for event in pygame.event.get():
        if event.type == pygame.QUIT: running = False

        elif event.type == pg.KEYDOWN:
            if event.key == pg.K_ESCAPE: running = False
            elif event.key == pg.K_UP: go_u = True
            elif event.key == pg.K_DOWN: go_d = True
            elif event.key == pg.K_RIGHT: go_r = True
            elif event.key == pg.K_LEFT: go_l = True

        elif event.type == pg.KEYUP:
            if event.key == pg.K_UP: go_u = False
            elif event.key == pg.K_DOWN: go_d = False
            elif event.key == pg.K_RIGHT: go_r = False
            elif event.key == pg.K_LEFT: go_l = False

    # erase and store the previous ball position
    screen.fill(grey, ball)
    old_pos = ball.move(0, 0)

    # ajust velocities
    vel[1] += gravity
    if go_u: vel[1] -= power
    if go_d: vel[1] += power
    if go_r: vel[0] += power
    if go_l: vel[0] -= power

    # move the ball according to its velocity
    ball.move_ip(vel)

    # stop the ball going off the screen
    if ball.bottom > y:
        ball.bottom = y
        vel[1] = -abs(vel[1]) * elasticity
    if ball.top < 0:
        ball.top = 0
        vel[1] = abs(vel[1]) * elasticity
    if ball.right > x:
        ball.right = x
        vel[0] = -abs(vel[0]) * elasticity
    if ball.left < 0:
        ball.left = 0
        vel[0] = abs(vel[0]) * elasticity

    # draw the new ball position and update the screen
    pygame.draw.ellipse(screen, green, ball)
    pygame.display.update(ball.union(old_pos))

# this is a game right, then we /need/ a quit message...
print 'My game not good enough for you aye.. then piss off! XD'