From cea85fd39722335610344cab912f2c63fe96c3de Mon Sep 17 00:00:00 2001
From: Cory Forsstrom <cforsstrom18@gmail.com>
Date: Tue, 11 Aug 2020 14:42:39 -0700
Subject: [PATCH] init draft of custom rodio source for audio

---
 .gitignore                            |  3 +-
 crates/bevy_audio/src/audio_output.rs | 43 +++++++++++++++++----------
 crates/bevy_audio/src/audio_source.rs | 16 +++++++++-
 crates/bevy_audio/src/lib.rs          |  9 ++++--
 examples/audio/audio.rs               |  2 +-
 5 files changed, 52 insertions(+), 21 deletions(-)

diff --git a/.gitignore b/.gitignore
index b3c22eedfbd838..840c8c0bb1390b 100644
--- a/.gitignore
+++ b/.gitignore
@@ -2,4 +2,5 @@
 **/*.rs.bk
 Cargo.lock
 .cargo/config
-/.idea
\ No newline at end of file
+/.idea
+/.vscode
diff --git a/crates/bevy_audio/src/audio_output.rs b/crates/bevy_audio/src/audio_output.rs
index 5b578fbfebde9a..3d61bb2366fe57 100644
--- a/crates/bevy_audio/src/audio_output.rs
+++ b/crates/bevy_audio/src/audio_output.rs
@@ -1,16 +1,22 @@
-use crate::AudioSource;
+use crate::Decodable;
 use bevy_asset::{Assets, Handle};
 use bevy_ecs::Res;
-use rodio::{Decoder, Device, Sink};
-use std::{collections::VecDeque, io::Cursor, sync::RwLock};
+use rodio::{Device, Sink};
+use std::{collections::VecDeque, sync::RwLock};
 
 /// Used to play audio on the current "audio device"
-pub struct AudioOutput {
+pub struct AudioOutput<P>
+where
+    P: Decodable,
+{
     device: Device,
-    queue: RwLock<VecDeque<Handle<AudioSource>>>,
+    queue: RwLock<VecDeque<Handle<P>>>,
 }
 
-impl Default for AudioOutput {
+impl<P> Default for AudioOutput<P>
+where
+    P: Decodable,
+{
     fn default() -> Self {
         Self {
             device: rodio::default_output_device().unwrap(),
@@ -19,18 +25,23 @@ impl Default for AudioOutput {
     }
 }
 
-impl AudioOutput {
-    pub fn play_source(&self, audio_source: &AudioSource) {
+impl<P> AudioOutput<P>
+where
+    P: Decodable,
+    <P as Decodable>::Decoder: rodio::Source + Send + Sync,
+    <<P as Decodable>::Decoder as Iterator>::Item: rodio::Sample + Send + Sync,
+{
+    pub fn play_source(&self, audio_source: &P) {
         let sink = Sink::new(&self.device);
-        sink.append(Decoder::new(Cursor::new(audio_source.clone())).unwrap());
+        sink.append(audio_source.decoder());
         sink.detach();
     }
 
-    pub fn play(&self, audio_source: Handle<AudioSource>) {
+    pub fn play(&self, audio_source: Handle<P>) {
         self.queue.write().unwrap().push_front(audio_source);
     }
 
-    pub fn try_play_queued(&self, audio_sources: &Assets<AudioSource>) {
+    pub fn try_play_queued(&self, audio_sources: &Assets<P>) {
         let mut queue = self.queue.write().unwrap();
         let len = queue.len();
         let mut i = 0;
@@ -48,9 +59,11 @@ impl AudioOutput {
 }
 
 /// Plays audio currently queued in the [AudioOutput] resource
-pub(crate) fn play_queued_audio_system(
-    audio_sources: Res<Assets<AudioSource>>,
-    audio_output: Res<AudioOutput>,
-) {
+pub fn play_queued_audio_system<P>(audio_sources: Res<Assets<P>>, audio_output: Res<AudioOutput<P>>)
+where
+    P: Decodable,
+    <P as Decodable>::Decoder: rodio::Source + Send + Sync,
+    <<P as Decodable>::Decoder as Iterator>::Item: rodio::Sample + Send + Sync,
+{
     audio_output.try_play_queued(&audio_sources);
 }
diff --git a/crates/bevy_audio/src/audio_source.rs b/crates/bevy_audio/src/audio_source.rs
index 16a032e3ae31ea..3635d802dcc59f 100644
--- a/crates/bevy_audio/src/audio_source.rs
+++ b/crates/bevy_audio/src/audio_source.rs
@@ -1,6 +1,6 @@
 use anyhow::Result;
 use bevy_asset::AssetLoader;
-use std::{path::Path, sync::Arc};
+use std::{io::Cursor, path::Path, sync::Arc};
 
 /// A source of audio data
 #[derive(Clone)]
@@ -30,3 +30,17 @@ impl AssetLoader<AudioSource> for Mp3Loader {
         EXTENSIONS
     }
 }
+
+pub trait Decodable: Send + Sync + 'static {
+    type Decoder;
+
+    fn decoder(&self) -> Self::Decoder;
+}
+
+impl Decodable for AudioSource {
+    type Decoder = rodio::Decoder<Cursor<AudioSource>>;
+
+    fn decoder(&self) -> Self::Decoder {
+        rodio::Decoder::new(Cursor::new(self.clone())).unwrap()
+    }
+}
diff --git a/crates/bevy_audio/src/lib.rs b/crates/bevy_audio/src/lib.rs
index 46270278f58da9..945ba853f60009 100644
--- a/crates/bevy_audio/src/lib.rs
+++ b/crates/bevy_audio/src/lib.rs
@@ -5,7 +5,7 @@ pub use audio_output::*;
 pub use audio_source::*;
 
 pub mod prelude {
-    pub use crate::{AudioOutput, AudioSource};
+    pub use crate::{AudioOutput, AudioSource, Decodable};
 }
 
 use bevy_app::prelude::*;
@@ -18,9 +18,12 @@ pub struct AudioPlugin;
 
 impl Plugin for AudioPlugin {
     fn build(&self, app: &mut AppBuilder) {
-        app.init_resource::<AudioOutput>()
+        app.init_resource::<AudioOutput<AudioSource>>()
             .add_asset::<AudioSource>()
             .add_asset_loader::<AudioSource, Mp3Loader>()
-            .add_system_to_stage(stage::POST_UPDATE, play_queued_audio_system.system());
+            .add_system_to_stage(
+                stage::POST_UPDATE,
+                play_queued_audio_system::<AudioSource>.system(),
+            );
     }
 }
diff --git a/examples/audio/audio.rs b/examples/audio/audio.rs
index 21744477c8ce15..1be30281575d8a 100644
--- a/examples/audio/audio.rs
+++ b/examples/audio/audio.rs
@@ -8,7 +8,7 @@ fn main() {
         .run();
 }
 
-fn setup(asset_server: Res<AssetServer>, audio_output: Res<AudioOutput>) {
+fn setup(asset_server: Res<AssetServer>, audio_output: Res<AudioOutput<AudioSource>>) {
     let music = asset_server
         .load("assets/sounds/Windless Slopes.mp3")
         .unwrap();