Sounds and Held Keys

Part of the Sound and Game Feel section of Coddy's Pygame journey. Lesson 4 of 23.

Hold Space and the ship fires a laser every 12 frames. The starter plays the laser sound like this:

if keys[pygame.K_SPACE]:
    laser_sound.play()
    if cooldown == 0:
        lasers.append(...)

keys[pygame.K_SPACE] is true on every frame the key is down. So while you hold Space, the sound starts 60 times a second, although only 5 lasers fly. You hear a rough buzz instead of shots.

The fix is the same rule as before: play the sound where the thing happens. A shot happens inside if cooldown == 0:, so the sound goes there:

if keys[pygame.K_SPACE]:
    if cooldown == 0:
        lasers.append(...)
        laser_sound.play()

Now every laser has its sound and nothing else does. For an action that happens once per press, such as a jump, play the sound in the KEYDOWN event instead: there is one event per press, however long the key stays down.

Challenge

Easy

Hold Space and the ship fires a laser every 12 frames, but the sound buzzes. Move laser_sound.play() so it plays once for each laser fired: into the if cooldown == 0: branch, after the laser is added.

Try it yourself

import pygame

pygame.init()
screen = pygame.display.set_mode((480, 360))
pygame.display.set_caption("Lasers")
clock = pygame.time.Clock()

laser_sound = pygame.mixer.Sound("assets/sounds/laser.ogg")
laser_sound.set_volume(0.5)

ship = pygame.Rect(220, 300, 40, 30)
lasers = []
cooldown = 0

running = True
while running:
    for event in pygame.event.get():
        if event.type == pygame.QUIT:
            running = False

    keys = pygame.key.get_pressed()
    if keys[pygame.K_LEFT]:
        ship.x -= 5
    if keys[pygame.K_RIGHT]:
        ship.x += 5
    ship.clamp_ip(screen.get_rect())

    if cooldown > 0:
        cooldown -= 1
    if keys[pygame.K_SPACE]:
        laser_sound.play()
        if cooldown == 0:
            lasers.append(pygame.Rect(ship.centerx - 2, ship.top - 12, 4, 12))
            cooldown = 12

    for laser in lasers:
        laser.y -= 8
    lasers = [laser for laser in lasers if laser.bottom > 0]

    screen.fill((30, 30, 46))
    for laser in lasers:
        pygame.draw.rect(screen, (255, 230, 90), laser)
    pygame.draw.rect(screen, (80, 200, 230), ship)
    pygame.display.flip()
    clock.tick(60)

pygame.quit()