Audio Sink Creation Delayed and Multiple Sinks Spawned

[ivanstepanovftw]

Bevy version

main aaccbe8

Relevant system information

• Fedora Linux 40 (Workstation Edition)

  $ uname -a
  Linux fedora 6.8.11-300.fc40.x86_64 #1 SMP PREEMPT_DYNAMIC Mon May 27 14:53:33 UTC 2024 x86_64 GNU/Linux
  

What you did

Tried to play audio if it is not yet playing in Update system loop.

use bevy::audio::Volume;
use bevy::ecs::query::QuerySingleError;
use bevy::prelude::*;

fn main() {
    App::new()
        .add_plugins(DefaultPlugins)
        .add_systems(Update, _update_spawn_audio)
        .run();
}

#[derive(Component)]
pub struct Beatmap;

fn _update_spawn_audio(
    mut commands: Commands,
    asset_server: Res<AssetServer>,
    query: Query<&AudioSink, With<Beatmap>>
) {
    println!("Query: {}", query.iter().count());

    match query.get_single() {
        Ok(sink) => {
            println!("Ok(sink)");
        }
        Err(QuerySingleError::NoEntities(_)) => {
            println!("Err(QuerySingleError::NoEntities(_))");

            commands.spawn((
                Beatmap,
                AudioBundle {
                    source: asset_server.load("sounds/loop.ogg"),
                    settings: PlaybackSettings::LOOP.with_volume(Volume::new(0.1))
                },
            ));
        }
        Err(QuerySingleError::MultipleEntities(_)) => {
            println!("QuerySingleError::MultipleEntities(_)");
        }
    }
}

Output:

Query: 0
Err(QuerySingleError::NoEntities(_))
Query: 0
Err(QuerySingleError::NoEntities(_))
Query: 2
QuerySingleError::MultipleEntities(_)

After suggestion to use Resources, tried to manually loop audio:

use bevy::prelude::*;

fn main() {
    App::new()
        .add_plugins(DefaultPlugins)
        .add_systems(Update, (
            update,
        ))
        .run();
}

#[derive(Resource)]
pub struct Beatmap {
    entity: Entity,
}

#[derive(Component)]
pub struct BeatmapAudio;

fn update(
    mut commands: Commands,
    asset_server: Res<AssetServer>,
    beatmap: Option<ResMut<Beatmap>>,
    query_sink: Query<&AudioSink, With<BeatmapAudio>>,
) {
    match beatmap {
        Some(beatmap) => {
            if query_sink.iter().count() >= 2 {
                println!("bug: sink count: {:?}", query_sink.iter().count());
            }
            if query_sink.iter().count() == 0 {
                commands.remove_resource::<Beatmap>();
            }
        }
        None => {
            let entity = commands.spawn((
                BeatmapAudio,
                AudioBundle {
                    source: asset_server.load("sounds/tss.wav"),
                    settings: PlaybackSettings::DESPAWN
                },
            )).id();
            commands.insert_resource(Beatmap {
                entity,
            });
        }
    }
}

Output:

bug: sink count: 2
...

What went wrong

• Expected that audio sink is created immediately.
• Instead, sink is created 2 frames later.
• Expected that it is possible to manually loop the audio.
• Instead, 2 sinks created.

Additional information

Related discussions:

• Discord: https://discord.com/channels/691052431525675048/1251696503437791272
• Reddit: https://www.reddit.com/r/bevy/comments/1dgw4im/how_to_immediately_spawn_entity_for_a_system_with/

[alice-i-cecile]

This is a likely cause of #13876.