Pygame Bit Mask Collision Example

import pygame
import math

# example of bit mask collision
# fb.com/groups/pygame

pygame.init()
surface = pygame.display.set_mode((640, 480))


black = [0, 0, 0]
red = [255, 0, 0]
blue = [0, 0, 255]

# create two sprites
surf1 = pygame.Surface((60, 60))
pygame.draw.circle(surf1, red, (15, 15), 15, 0)
pygame.draw.rect(surf1, red, (30, 30, 30, 30))
surf2 = pygame.Surface((60, 60))
pygame.draw.circle(surf2, blue, (45, 45), 15, 0)
pygame.draw.rect(surf2, blue, (0, 0, 30, 30))

# make the black background of the sprites transparent
surf1.set_colorkey(black)
surf2.set_colorkey(black)

# get the sprites bit masks
surf1_bitmask = pygame.mask.from_surface(surf1)
surf2_bitmask = pygame.mask.from_surface(surf2)

x = 290
y = 180
dead = False

# press ESCAPE to exit
while True:
    e = pygame.event.get()
    if pygame.key.get_pressed()[pygame.K_ESCAPE]: break

    mx, my = pygame.mouse.get_pos()

    # work out if the sprites bitmasks overlap
    if surf1_bitmask.overlap(surf2_bitmask, (mx - x, my - y)):
        dead = True

    surface.fill(black)
    if not dead: surface.blit(surf1, (x, y))
    surface.blit(surf2, (mx, my))

    pygame.display.update()
    pygame.time.Clock().tick(60)

pygame.quit()