bevy_openal/src/lib.rs

use std::collections::HashMap;
use std::io::Cursor;
use std::sync::Arc;

pub use alto::Source;
use alto::{Alto, Context, Mono, StaticSource, Stereo};
use bevy::{
    asset::{AssetLoader, HandleId, LoadContext, LoadedAsset},
    prelude::*,
    reflect::TypeUuid,
    utils::BoxedFuture,
};
use lewton::inside_ogg::OggStreamReader;

#[derive(Clone, Debug, TypeUuid)]
#[uuid = "aa22d11e-3bed-11eb-8708-00155dea3db9"]
pub struct Buffer {
    samples: Vec<i16>,
    sample_rate: i32,
    channels: u16,
}

#[derive(Clone, Copy, Debug, Default)]
pub struct BufferAssetLoader;

impl AssetLoader for BufferAssetLoader {
    fn load<'a>(
        &'a self,
        bytes: &'a [u8],
        load_context: &'a mut LoadContext,
    ) -> BoxedFuture<'a, Result<(), anyhow::Error>> {
        Box::pin(async move {
            let cursor = Cursor::new(bytes.to_vec());
            let buffer: Option<Buffer> =
                match load_context.path().extension().unwrap().to_str().unwrap() {
                    "ogg" => {
                        let mut stream = OggStreamReader::new(cursor)?;
                        let mut samples: Vec<i16> = vec![];
                        while let Some(pck_samples) = &mut stream.read_dec_packet_itl()? {
                            samples.append(pck_samples);
                        }
                        Some(Buffer {
                            samples,
                            channels: stream.ident_hdr.audio_channels as u16,
                            sample_rate: stream.ident_hdr.audio_sample_rate as i32,
                        })
                    }
                    "wav" => {
                        let reader = hound::WavReader::new(cursor);
                        if let Ok(mut reader) = reader {
                            let mut samples: Vec<i16> = vec![];
                            for sample in reader.samples::<i16>() {
                                if let Ok(sample) = sample {
                                    samples.push(sample);
                                }
                            }
                            Some(Buffer {
                                samples,
                                sample_rate: reader.spec().sample_rate as i32,
                                channels: reader.spec().channels,
                            })
                        } else {
                            None
                        }
                    }
                    _ => None,
                };
            if let Some(buffer) = buffer {
                load_context.set_default_asset(LoadedAsset::new(buffer));
            }
            Ok(())
        })
    }

    fn extensions(&self) -> &[&str] {
        &["mp3", "ogg", "wav"]
    }
}

#[derive(Default)]
struct Buffers(HashMap<HandleId, Arc<alto::Buffer>>);

fn buffer_creation_system(
    context: Res<Context>,
    mut buffers: ResMut<Buffers>,
    mut event_reader: Local<EventReader<AssetEvent<Buffer>>>,
    events: Res<Events<AssetEvent<Buffer>>>,
    assets: Res<Assets<Buffer>>,
) {
    for event in event_reader.iter(&events) {
        match event {
            AssetEvent::Created { handle } => {
                if let Some(buffer) = assets.get(handle) {
                    let buffer = match buffer.channels {
                        1 => {
                            context.new_buffer::<Mono<i16>, _>(&buffer.samples, buffer.sample_rate)
                        }
                        2 => context
                            .new_buffer::<Stereo<i16>, _>(&buffer.samples, buffer.sample_rate),
                        _ => {
                            panic!("Unsupported channel count");
                        }
                    };
                    if let Ok(buffer) = buffer {
                        buffers.0.insert(handle.id, Arc::new(buffer));
                    }
                }
            }
            AssetEvent::Modified { handle: _ } => {}
            AssetEvent::Removed { handle } => {
                buffers.0.remove(&handle.id);
            }
        }
    }
}

#[derive(Reflect)]
#[reflect(Component)]
pub struct Sound {
    pub buffer: Handle<Buffer>,
    pub autoplay: bool,
    pub gain: f32,
    pub looping: bool,
    #[reflect(ignore)]
    pub source: Option<StaticSource>,
}

impl Default for Sound {
    fn default() -> Self {
        Self {
            buffer: Default::default(),
            autoplay: false,
            gain: 1.,
            looping: false,
            source: None,
        }
    }
}
pub type Sounds = HashMap<String, Sound>;

fn source_system(
    context: Res<Context>,
    buffers: Res<Buffers>,
    mut query: Query<(&mut Sounds, Option<&Transform>)>,
) {
    for (mut sounds, transform) in query.iter_mut() {
        for mut sound in sounds.values_mut() {
            if sound.source.is_none() {
                if let Ok(mut source) = context.new_static_source() {
                    if let Some(buffer) = buffers.0.get(&sound.buffer.id) {
                        source.set_buffer(buffer.clone()).unwrap();
                    }
                    if sound.autoplay {
                        source.play();
                    }
                    sound.source = Some(source);
                }
            }
            if let Some(source) = sound.source.as_mut() {
                source.set_gain(sound.gain).unwrap();
                source.set_looping(sound.looping);
                if let Some(transform) = transform {
                    source.set_relative(false);
                    source
                        .set_position([
                            transform.translation.x,
                            transform.translation.y,
                            transform.translation.z,
                        ])
                        .unwrap();
                } else {
                    source.set_relative(true);
                    source.set_position([0., 0., 0.]).unwrap();
                }
            }
        }
    }
}

#[derive(Clone, Copy, Debug, Default, Reflect)]
#[reflect(Component)]
pub struct Listener;

fn update_listener_system(context: ResMut<Context>, query: Query<(&Listener, Option<&Transform>)>) {
    for (_, transform) in query.iter() {
        if let Some(transform) = transform {
            let matrix = transform.compute_matrix().inverse();
            let look = matrix.x_axis;
            let up = matrix.z_axis;
            context
                .set_position([
                    transform.translation.x,
                    transform.translation.y,
                    transform.translation.z,
                ])
                .unwrap();
            context
                .set_orientation(([look.x, look.y, look.z], [up.x, up.y, up.z]))
                .unwrap();
        } else {
            context.set_position([0., 0., 0.]).unwrap();
            context
                .set_orientation(([0., 0., 1.], [0., 1., 0.]))
                .unwrap();
        }
    }
}

pub struct OpenAlPlugin;

impl Plugin for OpenAlPlugin {
    fn build(&self, app: &mut AppBuilder) {
        let al = Alto::load_default().expect("Could not load alto");
        let device = al.open(None).expect("Could not open device");
        let context = device.new_context(None).expect("Could not create context");
        app.add_asset::<Buffer>()
            .init_asset_loader::<BufferAssetLoader>()
            .add_resource(context)
            .add_resource(Buffers::default())
            .register_type::<Listener>()
            .add_system(buffer_creation_system)
            .add_system(source_system)
            .add_system(update_listener_system);
    }
}