pygame shaking window when loosing lifes

Question

I've been trying to develop a small shooting game and i'd like the window to shake eveytime the hero gets hit or looses a life, i was thinkingto maybe reposition the window 3 times in a very shot time but im not sure how to implement this and still keep the game running. Here is my code for my main game loop: ``` def game(): #set screen width = 800 height = 600 pygame.init() screen = pygame.display.set_mode((width, height)) pygame.display.set_caption('UoN Invaders: Game') background = pygame.Surface(screen.get_size()) background = background.convert() background.fill((000, 000, 000)) screen.blit(background, (0, 0)) pygame.display.flip() #load music with help of helpers.py music = pygame.mixer.music.load ("data/spacequest.mp3") pygame.mixer.music.play(-1) global clock, player, playerSprite, enemySprites, enemiestocreat global enemiesset, lvl2, laserSprites, enemyExplosion, playerExplosion, explosionSprites clock = pygame.time.Clock() i = 0 #setting i that define if the game is just sta…

Accepted Answer

A simple solution is to not draw to the screen `Surface` directly, but to a temporary `Surface`. Then blit that temporary `Surface` to the screen `Surface`.

If you want to shake the screen, simply apply an offset to the position of the temporary `Surface` while blitting.

To generate that offset, you can make use of a generator function.

Here's a complete example. Note how the screen shakes if the player is hit by a falling rock.

```
import pygame
from random import randint
from itertools import repeat

pygame.init()
org_screen = pygame.display.set_mode((400, 400))
screen = org_screen.copy()
screen_rect = screen.get_rect()
player = pygame.Rect(180, 180, 20, 20)

def get_rock():
    return pygame.Rect(randint(0, 340), 0, 60, 60)

falling = get_rock()
clock = pygame.time.Clock()

# 'offset' will be our generator that produces the offset
# in the beginning, we start with a generator that 
# yields (0, 0) forever
offset = repeat((0, 0))

# this function creates our shake-generator
# it "moves" the screen to the left and right
# three times by yielding (-5, 0), (-10, 0),
# ... (-20, 0), (-15, 0) ... (20, 0) three times,
# then keeps yieling (0, 0)
def shake():
    s = -1
    for _ in xrange(0, 3):
        for x in range(0, 20, 5):
            yield (x*s, 0)
        for x in range(20, 0, 5):
            yield (x*s, 0)
        s *= -1
    while True:
        yield (0, 0)

while True:
    if pygame.event.get(pygame.QUIT): break
    pygame.event.pump()

keys = pygame.key.get_pressed()
    if keys[pygame.K_w]: player.move_ip(0, -2)
    if keys[pygame.K_a]: player.move_ip(-2, 0)
    if keys[pygame.K_s]: player.move_ip(0, 2)
    if keys[pygame.K_d]: player.move_ip(2, 0)
    player.clamp_ip(screen_rect)

falling.move_ip(0, 4)
    org_screen.fill((0, 0, 0))
    screen.fill((255,255,255))
    pygame.draw.rect(screen, (0,0,0), player)
    pygame.draw.rect(screen, (255,0,0), falling)

if player.colliderect(falling):
        # if the player is hit by the rock,
        # we create a new shake-generator
        offset = shake()
        falling = get_rock()

if not screen_rect.contains(falling):
        falling = get_rock()

clock.tick(100)
    # here we draw our temporary surface to the
    # screen using the offsets created by the 
    # generators.
    org_screen.blit(screen, next(offset))
    pygame.display.flip()
```

pygame shaking window when loosing lifes

Solution

Problem