PyGame for Game Development: Sprite Groups and Collision Detection - Collision
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Sprite groups also provide a simple way to test for collision within your applications. PyGame contains three methods that allow us to test for collision, each behaving a bit differently than the rest. They are pygame.sprite.spritecollide, pygame.sprite.groupcollide and pygame.sprite.collideany. Let's create an example application featuring three non-playable StickMan sprites and one character StickMan sprite. A collision between the player and a non-playable sprite will create different results for each sprite:
import pygame
import sys
class StickMan(pygame.sprite.Sprite):
def __init__(self, position):
pygame.sprite.Sprite.__init__(self)
self.screen = pygame.display.get_surface().get_rect()
self.image = pygame.image.load('stickMan.gif')
self.rect = self.image.get_rect()
self.rect.x = position[0]
self.rect.y = position[1]
def update(self, amount):
self.rect = self.rect.move(amount)
# Check for offscreen movements
if self.rect.x < 0:
self.rect.x = 0
elif self.rect.x > (self.screen.width - self.rect.width):
self.rect.x = self.screen.width - self.rect.width
if self.rect.y < 0:
self.rect.y = 0
elif self.rect.y > (self.screen.height - self.rect.height):
self.rect.y = self.screen.height - self.rect.height
# Function to erase the sprite
def eraseSprite(screen, rect):
screen.blit(blank, rect)
pygame.init()
screen = pygame.display.set_mode((256, 256))
pygame.display.set_caption('Collision Detection')
screen.fill((255, 255, 255))
# Create three non-playable stickmen
stick1 = StickMan((25, 25))
stick2 = StickMan((100, 150))
stick3 = StickMan((175, 175))
# Add them each to a group
group1 = pygame.sprite.Group()
group2 = pygame.sprite.Group()
group3 = pygame.sprite.Group()
group1.add(stick1)
group2.add(stick2)
group3.add(stick3)
# Create a playable stickman and add it to a group
player = StickMan((200,10))
playerGroup = pygame.sprite.RenderUpdates()
playerGroup.add(player)
# Create a background piece
blank = pygame.Surface((player.rect.width, player.rect.height))
blank.fill((255, 255, 255))
# Draw each sprite
group1.draw(screen)
group2.draw(screen)
group3.draw(screen)
playerGroup.draw(screen)
pygame.display.update()
while True:
for event in pygame.event.get():
if event.type == pygame.QUIT:
pygame.quit()
# Move the player if a key is pressed
elif event.type == pygame.KEYDOWN:
if event.key == pygame.K_LEFT:
player.update([-10, 0])
elif event.key == pygame.K_UP:
player.update([0, -10])
elif event.key == pygame.K_RIGHT:
player.update([10, 0])
elif event.key == pygame.K_DOWN:
player.update([0, 10])
# Check to see if the player has collided with stick1 in
group1
# If a collision is detected, kill stick1 (True)
collide1 = pygame.sprite.spritecollide(player, group1,
True)
# Check to see if the playerGroup has collided with
group2
# Kill all involved sprites if there is a collision
collide2 = pygame.sprite.groupcollide(playerGroup,
group2, True, True)
# Check to see if the player has collided with anything
in group3
collide3 = pygame.sprite.spritecollideany(player,
group3)
# Print the test results
print 'Test 1:', collide1
print 'Test 2:', collide2
print 'Test 3:', collide3
# If the player has died, print a game over message,
wait and then quit
if not player.alive():
print 'Game Over'
pygame.time.wait(3000)
sys.exit()
# Clear the player's old spot
playerGroup.clear(screen, eraseSprite)
# Draw the player
updateRects = playerGroup.draw(screen)
# If we need to redraw other things, then do so
if collide1:
group1.clear(screen, eraseSprite)
group1.draw(screen)
updateRects.append(stick1.rect)
elif collide2:
group2.draw(screen)
updateRects.append(stick2.rect)
elif collide3:
group3.draw(screen)
updateRects.append(stick3.rect)
# Update everything
pygame.display.update(updateRects)
Next: Explaining the Collision Code >>
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