ball-bounce.py

import sys
import pygame
import math
from pygame.locals import *


WIDTH = 800
HEIGHT = 600

BLACK = Color(0, 0, 0)
BALL_COLOR = Color(255, 0, 0)
BALL_SIZE = 10

ballPosition = 100, 100
ballDirection = -5, 5

pygame.init()
screen = pygame.display.set_mode([WIDTH, HEIGHT])


while 1:
	# handle events
	for event in pygame.event.get():
		if event.type == pygame.QUIT:
			sys.exit()
		if event.type == pygame.KEYDOWN:
			if event.key == K_ESCAPE:
				sys.exit()

	# run game logic
	newX = ballPosition[0] + ballDirection[0]
	newY = ballPosition[1] + ballDirection[1]

	if newX < 0 or newX >= WIDTH:
		ballDirection = -ballDirection[0], ballDirection[1]
	
	if newY < 0 or newY >= HEIGHT:
		ballDirection = ballDirection[0], -ballDirection[1]
	
	ballPosition = newX, newY

	# render current frame
	screen.fill(BLACK)
	pygame.draw.circle(screen, BALL_COLOR, ballPosition, BALL_SIZE)

	pygame.display.flip()
	pygame.time.wait(10)