Programmed soundtrack example #12774

Remi-Godin · 2024-03-29T04:47:20Z

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

Objective

Fixes Add an audio example demonstrating how to play a soundtrack #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.

Create soundtrack example, added new assets, and updated credits.

github-actions · 2024-03-29T04:57:22Z

The generated examples/README.md is out of sync with the example metadata in Cargo.toml or the example readme template. Please run cargo run -p build-templated-pages -- update examples to update it, and commit the file change.

alice-i-cecile · 2024-03-29T12:55:19Z

CREDITS.md

@@ -28,6 +28,8 @@
 * 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)
 * `MorphStressTest.gltf`, [MorphStressTest] ([CC-BY 4.0] by Analytical Graphics, Inc, Model and textures by Ed Mackey)
+* Mysterious accoustic guitar music sample from [florianreichelt](https://freesound.org/people/florianreichelt/sounds/412429/) (CC0 license)


We can either fix this typo (which came from the link), or allow it in our typos config.

I think I'm in favor of fixing it: the link plus artist name should make this straightforward to discover the source anyways.

Cargo.toml

examples/audio/soundtrack.rs

alice-i-cecile · 2024-03-29T12:57:22Z

examples/audio/soundtrack.rs

+    commands.insert_resource(GameStateTimer(Timer::from_seconds(10.0, TimerMode::Repeating)));
+
+    // Create the track list
+    let track_1 = asset_server.load::<AudioSource>("sounds/Mysterious accoustic guitar.ogg");


Yeah, the way this propagates through is unfortunate.

What's the best approach for me to fix this? Do I make a suggestion for every line of code that is affected, or do I "Request Changes" ? Still kind of new to contributing to projects, so unsure of how to proceed from here.

As the author, just push changes to your branch that fix the issue.

examples/audio/soundtrack.rs

alice-i-cecile

Just a bit of cleanup :) Really glad this exists, and I'm happy with the approach taken to fade.

bushrat011899

Nice example! Audio is an often overlooked element in game engines, to their detriment.

examples/audio/soundtrack.rs

Remi-Godin · 2024-03-29T14:47:50Z

Glad my approach was satisfactory!

github-actions · 2024-03-29T16:32:42Z

The generated examples/README.md is out of sync with the example metadata in Cargo.toml or the example readme template. Please run cargo run -p build-templated-pages -- update examples to update it, and commit the file change.

Remi-Godin · 2024-03-29T16:43:12Z

Apologies, I didn't realize if I pushed to my fork, it was going to reflect on this PR (still new to all this). My intention was not to pollute this PR with unnecessary commits.

I fixed the typo issue and changed the run condition as suggested. However, I forgot to add the comment changes that were suggested to better reflect the purpose of this example.

I also did not change to use keyboard input yet, was waiting for more feedback on it first.

I will be more careful in the future.

alice-i-cecile

Once you've regenerated the example text (CI will yell at you), this is good to merge.

github-actions · 2024-03-29T18:21:03Z

The generated examples/README.md is out of sync with the example metadata in Cargo.toml or the example readme template. Please run cargo run -p build-templated-pages -- update examples to update it, and commit the file change.

SolarLiner · 2024-03-29T20:41:15Z

examples/audio/soundtrack.rs

+                        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(),


Since the tracklist is not dynamic, I think having named fields in the SoundtrackPlayer resource would make more sense, and remove the indexing accesses into the vec here.

I did consider this, but was worried that making it too "static" would not be good for the example, so I decided to go with a Vec to show that this is flexible. I almost created a struct to hold not only the track, but a title and volume setting as well since the original issue mentioned configurable volume, but opted against this for simplicity. This is my first example so still not sure as to how in depth they need to be, or how flexible/dynamic they should be.

I also used unwrap() statements instead of doing proper error handling since I wanted to keep the code simple and focused on the subject of the example, and if it cannot get the files, then there's not really any point in running the example and panicking should be fine. I also saw that other examples also uses unwrap() statements.

If I do write other examples in the future, I will make sure to keep your feedback in mind. Any other feedback or pointers is also appreciated.

SolarLiner · 2024-03-29T21:04:22Z

examples/audio/soundtrack.rs

+    time: Res<Time>,
+) {
+    for (audio, entity) in audio_sink.iter_mut() {
+        audio.set_volume(audio.volume() + time.delta_seconds() / FADE_TIME);


Nothing we can do at this stage for the example but this highlights the need for tweening in the audio engine -- this is going to result in sounding like stepwise motion, because it will only update as fast as the game renders (which is 60 or maybe even 120 Hz which is definitely not fast enough to perceive as gradual).

In this case because the fade is 2 seconds each increment is going to be gradual enough, but shorten the fade time and the problem manifests more clearly.

This is also something I considered while programming this. Also, I just did a linear fade on the volume setting, but according to the docs, to decrease the perceived volume by half, you should multiply by 0.316. I figured it was good enough at illustrating the concept while still keeping things simple.

Programmed soundtrack example

a4cc796

Create soundtrack example, added new assets, and updated credits.

alice-i-cecile added C-Examples An addition or correction to our examples A-Audio Sounds playback and modification labels Mar 29, 2024