Music for Each State

Part of the Sound and Game Feel section of Coddy's Pygame journey. Lesson 6 of 23.

Each state of a game can have its own music: a calm theme on the menu, a busy track while you play, a short tune when you win or lose. To switch, load the new track and play it. Loading a new track stops the old one. A small function keeps the two lines together:

def play_music(path, loops=-1):
    pygame.mixer.music.load(path)
    pygame.mixer.music.play(loops)

Switch the music at the moment the state changes, on the line that sets state:

if player.colliderect(goal):
    state = "win"
    play_music("assets/music/win.ogg", 0)

That line runs once, so the track starts once. Do not switch inside if state == "win": in the drawing part: that runs on every frame and restarts the track 60 times a second.

The win and lose tunes are short and end on their own, so they take loops 0. The theme and the level track loop with -1.

Challenge

Medium

Enter starts the game; the blue square wins at the green goal and loses in the lava. Give each state its music:

Write play_music(path, loops=-1) that loads and plays a track.
Before the loop, play assets/music/theme.ogg.
Where the state becomes "play", play assets/music/level.ogg.
Where it becomes "win", play assets/music/win.ogg once (loops 0); for "lose", assets/music/lose.ogg once.
Where Enter goes back to "menu", play theme.ogg again.

Try it yourself

import pygame

pygame.init()
screen = pygame.display.set_mode((480, 360))
pygame.display.set_caption("Lava Run")
clock = pygame.time.Clock()
font = pygame.font.Font(None, 32)

player = pygame.Rect(40, 160, 30, 30)
goal = pygame.Rect(420, 160, 30, 30)
lava = pygame.Rect(0, 320, 480, 40)
state = "menu"

running = True
while running:
    for event in pygame.event.get():
        if event.type == pygame.QUIT:
            running = False
        elif event.type == pygame.KEYDOWN and event.key == pygame.K_RETURN:
            if state == "menu":
                state = "play"
                player.topleft = (40, 160)
            elif state in ("win", "lose"):
                state = "menu"

    if state == "play":
        keys = pygame.key.get_pressed()
        if keys[pygame.K_LEFT]:
            player.x -= 4
        if keys[pygame.K_RIGHT]:
            player.x += 4
        if keys[pygame.K_UP]:
            player.y -= 4
        if keys[pygame.K_DOWN]:
            player.y += 4
        player.clamp_ip(screen.get_rect())
        if player.colliderect(goal):
            state = "win"
        elif player.colliderect(lava):
            state = "lose"

    screen.fill((30, 30, 46))
    if state == "menu":
        title = font.render("Press Enter to start", True, (240, 240, 240))
        screen.blit(title, title.get_rect(center=(240, 180)))
    else:
        pygame.draw.rect(screen, (230, 90, 40), lava)
        pygame.draw.rect(screen, (90, 200, 120), goal)
        pygame.draw.rect(screen, (80, 160, 255), player)
        if state == "win":
            message = font.render("You win!", True, (240, 240, 240))
            screen.blit(message, message.get_rect(center=(240, 100)))
        elif state == "lose":
            message = font.render("Game over", True, (240, 240, 240))
            screen.blit(message, message.get_rect(center=(240, 100)))
    pygame.display.flip()
    clock.tick(60)

pygame.quit()