Pygame Distance Collision Example

import pygame
import math

# example of collision based on distance
# 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]

x = 320
y = 240
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()

    # calculate the distance between the centre of the surface and mouse location
    # if the distance is less than the combine radius (60) of the two circles then
    # a collision has occured.
    if math.sqrt((mx - x) ** 2 + (my - y) ** 2) < 60:
        dead = True

    surface.fill(black)
    if not dead: pygame.draw.circle(surface, red, (x, y), 30)
    pygame.draw.circle(surface, blue, (mx, my), 30)

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

pygame.quit()