abf12f3b3b
Links in the api docs are nice. I noticed that there were several places where structs / functions and other things were referenced in the docs, but weren't linked. I added the links where possible / logical. --------- Co-authored-by: Alice Cecile <alice.i.cecile@gmail.com> Co-authored-by: François <mockersf@gmail.com>
103 lines
2.9 KiB
Rust
103 lines
2.9 KiB
Rust
//! Shows how to create a custom [`Decodable`] type by implementing a Sine wave.
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use bevy::audio::AddAudioSource;
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use bevy::audio::AudioPlugin;
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use bevy::audio::Source;
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use bevy::prelude::*;
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use bevy::reflect::TypeUuid;
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use bevy::utils::Duration;
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// This struct usually contains the data for the audio being played.
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// This is where data read from an audio file would be stored, for example.
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// Implementing `TypeUuid` will automatically implement `Asset`.
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// This allows the type to be registered as an asset.
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#[derive(TypeUuid)]
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#[uuid = "c2090c23-78fd-44f1-8508-c89b1f3cec29"]
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struct SineAudio {
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frequency: f32,
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}
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// This decoder is responsible for playing the audio,
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// and so stores data about the audio being played.
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struct SineDecoder {
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// how far along one period the wave is (between 0 and 1)
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current_progress: f32,
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// how much we move along the period every frame
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progress_per_frame: f32,
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// how long a period is
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period: f32,
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sample_rate: u32,
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}
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impl SineDecoder {
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fn new(frequency: f32) -> Self {
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// standard sample rate for most recordings
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let sample_rate = 44_100;
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SineDecoder {
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current_progress: 0.,
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progress_per_frame: frequency / sample_rate as f32,
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period: std::f32::consts::PI * 2.,
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sample_rate,
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}
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}
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}
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// The decoder must implement iterator so that it can implement `Decodable`.
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impl Iterator for SineDecoder {
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type Item = f32;
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fn next(&mut self) -> Option<Self::Item> {
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self.current_progress += self.progress_per_frame;
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// we loop back round to 0 to avoid floating point inaccuracies
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self.current_progress %= 1.;
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Some(f32::sin(self.period * self.current_progress))
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}
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}
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// `Source` is what allows the audio source to be played by bevy.
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// This trait provides information on the audio.
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impl Source for SineDecoder {
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fn current_frame_len(&self) -> Option<usize> {
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None
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}
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fn channels(&self) -> u16 {
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1
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}
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fn sample_rate(&self) -> u32 {
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self.sample_rate
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}
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fn total_duration(&self) -> Option<Duration> {
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None
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}
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}
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// Finally `Decodable` can be implemented for our `SineAudio`.
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impl Decodable for SineAudio {
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type Decoder = SineDecoder;
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type DecoderItem = <SineDecoder as Iterator>::Item;
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fn decoder(&self) -> Self::Decoder {
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SineDecoder::new(self.frequency)
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}
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}
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fn main() {
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let mut app = App::new();
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// register the audio source so that it can be used
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app.add_plugins(DefaultPlugins.set(AudioPlugin {
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global_volume: GlobalVolume::new(0.2),
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}))
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.add_audio_source::<SineAudio>()
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.add_systems(Startup, setup)
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.run();
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}
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fn setup(mut assets: ResMut<Assets<SineAudio>>, audio: Res<Audio<SineAudio>>) {
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// add a `SineAudio` to the asset server so that it can be played
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let audio_handle = assets.add(SineAudio {
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frequency: 440., //this is the frequency of A4
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});
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audio.play(audio_handle);
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}
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