Part 6: Sound effects and music

In this chapter we’ll add sound effects and music to the game.

Loading sound effects from files

Loading sound effect from file is easy:

from kaa.audio import Sound
my_sound = Sound('/path/to/sound.wav')

Currently supported sound formats are:

• wav

• ogg

Playing sound effect

To play the sound effect:

my_sound.play(volume=0.9) # volume parameter ranging from 0 to 1, default is 1

You can play many sound effects simultaneously. There is a max limit of simultaneous sound that can be played. To change the limit use Scene’s audio.mixing_channels property.

Note

Setting max limit to a very large number and playing very large number of sounds simultaneously may degrate performace of your game.

Stopping sound effect being played

When you call play() on a Sound, kaa will play the whole sound. If you want to stop playing the sound effect manually, you need to wait until next version of kaa because stopping sound effects is not yet implemented.

Loading music files from files

Loading music tracks is very similar to loading sound effects:

from kaa.audio import Music
my_music_track = Music('/path/to/music_track.wav')

Currently supported music formats are:

• wav

• ogg

Playing music track

To play the music track call play on your Music object:

my_music_track.play(volume=1.0)

You can play only one music track at a time. Playing new music track automatically stops the current track being played.

Stopping music track

If you want to just stop the current track being played without replacing it with a new track:

from kaa.audio import Music
Music.get_current().stop()

Knowing when music track has ended

Typically you will like to know when the current music track has ended so you can select a new one. To do this look for the audio events in the Scene’s events() list:

class MyScene(Scene):

    def update(dt)

        for event in self.input.events():
            if event.audio: # check if it's an audio related event
                if event.audio.music_finished:
                    # do something when the track has finished playing ...

Full example

Let’s use the sound and music in our tutorial game.

First, let’s load all assets from files first, in our AssetsController

controllers/assets_controller.py

from kaa.audio import Sound, Music

class AssetsController:

    def __init__(self):

        # ..... rest of the function .....

        # Load all sounds
        self.mg_shot_sound = Sound(os.path.join('assets', 'sfx', 'mg-shot.wav'))
        self.force_gun_shot_sound = Sound(os.path.join('assets', 'sfx', 'force-gun-shot.wav'))
        self.grenade_launcher_shot_sound = Sound(os.path.join('assets', 'sfx', 'grenade-launcher-shot.wav'))
        self.explosion_sound = Sound(os.path.join('assets', 'sfx', 'explosion.wav'))

        # Load all music tracks
        self.music_track_1 = Music(os.path.join('assets', 'music', 'track_1.wav'))

Let’s play the music when the game starts.

main.py

with Engine(virtual_resolution=Vector(settings.VIEWPORT_WIDTH, settings.VIEWPORT_HEIGHT)) as engine:
    # initialize global controllers and remember them in the registry
    registry.global_controllers.assets_controller = AssetsController()
    # play music
    registry.global_controllers.assets_controller.music_track_1.play()

    # .... rest of the code ....

Note

main.py isn’t the best place to put this code. The music will stop playing after the track ends. To make it more usable maybe we should have a MusicController to manage tracks, and take care of starting new track when the previous ends? We’ll leave this task to you :)

Let’s play shooting sounds for the guns we have in the game:

objects/weapons/force_gun.py

class ForceGun(WeaponBase):

    def shoot_bullet(self):
        # .... rest of the function ....

        # play shooting sound
        registry.global_controllers.assets_controller.force_gun_shot_sound.play()

objects/weapons/grenade_launcher.py

class GrenadeLauncher(WeaponBase):

    def shoot_bullet(self):
        # .... rest of the function ....

        # play shooting sound
        registry.global_controllers.assets_controller.grenade_launcher_shot_sound.play()

objects/weapons/machine_gun.py

class MachineGun(WeaponBase):

    def shoot_bullet(self):
        # .... rest of the function ....

        # play shooting sound
        registry.global_controllers.assets_controller.mg_shot_sound.play()

And the explosion sound:

controllers/enemies_controller.py

class EnemiesController:

    def apply_explosion_effects(self, explosion_center, damage_at_center=40, blast_radius=150,
                                pushback_force_at_center=500, pushback_radius=300):
        # play explosion sound
        registry.global_controllers.assets_controller.explosion_sound.play()
        # .... rest of the function ....

Run the game and enjoy the experience with sounds and music. When you’re ready, move on to the part 7 of the tutorial where we’ll learn how to draw text.