Programmed soundtrack example (#12774)

Created soundtrack example, fade-in and fade-out features, added new
assets, and updated credits.

# Objective
- Fixes #12651 

## Solution
- Created a resource to hold the track list. 
- The audio assets are then loaded by the asset server and added to the
track list.
- Once the game is in a specific state, an `AudioBundle` is spawned and
plays the appropriate track.
- The audio volume starts at zero and is then incremented gradually
until it reaches full volume.
- Once the game state changes, the current track fades out, and a new
one fades in at the same time, offering a relatively seamless
transition.
- Once a track is completely faded out, it is despawned from the app.
- Game state changes are simulated through a `Timer` for simplicity.
- Track change system is only run if there is a change in the
`GameState` resource.
- All tracks are used according to their respective licenses.

---------

Co-authored-by: Alice Cecile <alice.i.cecile@gmail.com>
This commit is contained in:
Remi Godin 2024-03-29 13:32:30 -07:00 committed by GitHub
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@ -28,6 +28,8 @@
* FiraMono by The Mozilla Foundation and Telefonica S.A (SIL Open Font License, Version 1.1: assets/fonts/FiraMono-LICENSE) * FiraMono by The Mozilla Foundation and Telefonica S.A (SIL Open Font License, Version 1.1: assets/fonts/FiraMono-LICENSE)
* Barycentric from [mk_bary_gltf](https://github.com/komadori/mk_bary_gltf) (MIT OR Apache-2.0) * Barycentric from [mk_bary_gltf](https://github.com/komadori/mk_bary_gltf) (MIT OR Apache-2.0)
* `MorphStressTest.gltf`, [MorphStressTest] ([CC-BY 4.0] by Analytical Graphics, Inc, Model and textures by Ed Mackey) * `MorphStressTest.gltf`, [MorphStressTest] ([CC-BY 4.0] by Analytical Graphics, Inc, Model and textures by Ed Mackey)
* Mysterious acoustic guitar music sample from [florianreichelt](https://freesound.org/people/florianreichelt/sounds/412429/) (CC0 license)
* Epic orchestra music sample, modified to loop, from [Migfus20](https://freesound.org/people/Migfus20/sounds/560449/) ([CC BY 4.0 DEED](https://creativecommons.org/licenses/by/4.0/))
[MorphStressTest]: https://github.com/KhronosGroup/glTF-Sample-Models/tree/master/2.0/MorphStressTest [MorphStressTest]: https://github.com/KhronosGroup/glTF-Sample-Models/tree/master/2.0/MorphStressTest
[fox]: https://github.com/KhronosGroup/glTF-Sample-Models/tree/master/2.0/Fox [fox]: https://github.com/KhronosGroup/glTF-Sample-Models/tree/master/2.0/Fox

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@ -1389,6 +1389,17 @@ description = "Shows how to create and register a custom audio source by impleme
category = "Audio" category = "Audio"
wasm = true wasm = true
[[example]]
name = "soundtrack"
path = "examples/audio/soundtrack.rs"
doc-scrape-examples = true
[package.metadata.example.soundtrack]
name = "Soundtrack"
description = "Shows how to play different soundtracks based on game state"
category = "Audio"
wasm = true
[[example]] [[example]]
name = "spatial_audio_2d" name = "spatial_audio_2d"
path = "examples/audio/spatial_audio_2d.rs" path = "examples/audio/spatial_audio_2d.rs"

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@ -220,6 +220,7 @@ Example | Description
[Audio Control](../examples/audio/audio_control.rs) | Shows how to load and play an audio file, and control how it's played [Audio Control](../examples/audio/audio_control.rs) | Shows how to load and play an audio file, and control how it's played
[Decodable](../examples/audio/decodable.rs) | Shows how to create and register a custom audio source by implementing the `Decodable` type. [Decodable](../examples/audio/decodable.rs) | Shows how to create and register a custom audio source by implementing the `Decodable` type.
[Pitch](../examples/audio/pitch.rs) | Shows how to directly play a simple pitch [Pitch](../examples/audio/pitch.rs) | Shows how to directly play a simple pitch
[Soundtrack](../examples/audio/soundtrack.rs) | Shows how to play different soundtracks based on game state
[Spatial Audio 2D](../examples/audio/spatial_audio_2d.rs) | Shows how to play spatial audio, and moving the emitter in 2D [Spatial Audio 2D](../examples/audio/spatial_audio_2d.rs) | Shows how to play spatial audio, and moving the emitter in 2D
[Spatial Audio 3D](../examples/audio/spatial_audio_3d.rs) | Shows how to play spatial audio, and moving the emitter in 3D [Spatial Audio 3D](../examples/audio/spatial_audio_3d.rs) | Shows how to play spatial audio, and moving the emitter in 3D

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@ -0,0 +1,157 @@
//! This example illustrates how to load and play different soundtracks,
//! transitioning between them as the game state changes.
use bevy::prelude::*;
fn main() {
App::new()
.add_plugins(DefaultPlugins)
.add_systems(Startup, setup)
.add_systems(Update, (cycle_game_state, fade_in, fade_out))
.add_systems(Update, change_track)
.run();
}
// This resource simulates game states
#[derive(Resource, Default)]
enum GameState {
#[default]
Peaceful,
Battle,
}
// This timer simulates game state changes
#[derive(Resource)]
struct GameStateTimer(Timer);
// This resource will hold the track list for your soundtrack
#[derive(Resource)]
struct SoundtrackPlayer {
track_list: Vec<Handle<AudioSource>>,
}
impl SoundtrackPlayer {
fn new(track_list: Vec<Handle<AudioSource>>) -> Self {
Self { track_list }
}
}
// This component will be attached to an entity to fade the audio in
#[derive(Component)]
struct FadeIn;
// This component will be attached to an entity to fade the audio out
#[derive(Component)]
struct FadeOut;
fn setup(asset_server: Res<AssetServer>, mut commands: Commands) {
// Instantiate the game state resources
commands.insert_resource(GameState::default());
commands.insert_resource(GameStateTimer(Timer::from_seconds(
10.0,
TimerMode::Repeating,
)));
// Create the track list
let track_1 = asset_server.load::<AudioSource>("sounds/Mysterious acoustic guitar.ogg");
let track_2 = asset_server.load::<AudioSource>("sounds/Epic orchestra music.ogg");
let track_list = vec![track_1, track_2];
commands.insert_resource(SoundtrackPlayer::new(track_list));
}
// Every time the GameState resource changes, this system is run to trigger the song change.
fn change_track(
mut commands: Commands,
soundtrack_player: Res<SoundtrackPlayer>,
soundtrack: Query<Entity, With<AudioSink>>,
game_state: Res<GameState>,
) {
if game_state.is_changed() {
// Fade out all currently running tracks
for track in soundtrack.iter() {
commands.entity(track).insert(FadeOut);
}
// Spawn a new `AudioBundle` with the appropriate soundtrack based on
// the game state.
//
// Volume is set to start at zero and is then increased by the fade_in system.
match game_state.as_ref() {
GameState::Peaceful => {
commands.spawn((
AudioBundle {
source: soundtrack_player.track_list.first().unwrap().clone(),
settings: PlaybackSettings {
mode: bevy::audio::PlaybackMode::Loop,
volume: bevy::audio::Volume::ZERO,
..default()
},
},
FadeIn,
));
}
GameState::Battle => {
commands.spawn((
AudioBundle {
source: soundtrack_player.track_list.get(1).unwrap().clone(),
settings: PlaybackSettings {
mode: bevy::audio::PlaybackMode::Loop,
volume: bevy::audio::Volume::ZERO,
..default()
},
},
FadeIn,
));
}
}
}
}
// Fade effect duration
const FADE_TIME: f32 = 2.0;
// Fades in the audio of entities that has the FadeIn component. Removes the FadeIn component once
// full volume is reached.
fn fade_in(
mut commands: Commands,
mut audio_sink: Query<(&mut AudioSink, Entity), With<FadeIn>>,
time: Res<Time>,
) {
for (audio, entity) in audio_sink.iter_mut() {
audio.set_volume(audio.volume() + time.delta_seconds() / FADE_TIME);
if audio.volume() >= 1.0 {
audio.set_volume(1.0);
commands.entity(entity).remove::<FadeIn>();
}
}
}
// Fades out the audio of entities that has the FadeOut component. Despawns the entities once audio
// volume reaches zero.
fn fade_out(
mut commands: Commands,
mut audio_sink: Query<(&mut AudioSink, Entity), With<FadeOut>>,
time: Res<Time>,
) {
for (audio, entity) in audio_sink.iter_mut() {
audio.set_volume(audio.volume() - time.delta_seconds() / FADE_TIME);
if audio.volume() <= 0.0 {
commands.entity(entity).despawn_recursive();
}
}
}
// Every time the timer ends, switches between the "Peaceful" and "Battle" state.
fn cycle_game_state(
mut timer: ResMut<GameStateTimer>,
mut game_state: ResMut<GameState>,
time: Res<Time>,
) {
timer.0.tick(time.delta());
if timer.0.just_finished() {
match game_state.as_ref() {
GameState::Battle => *game_state = GameState::Peaceful,
GameState::Peaceful => *game_state = GameState::Battle,
}
}
}