From 3aa16685da4b62a0281a2816c9fcc234232611d1 Mon Sep 17 00:00:00 2001
From: Grant Shangreaux <grant@unabridgedsoftware.com>
Date: Sat, 16 Oct 2021 22:26:00 -0500
Subject: WIP: Make sound with rust

---
 klangfarbrs/src/lib.rs | 103 +++++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 103 insertions(+)

(limited to 'klangfarbrs/src')

diff --git a/klangfarbrs/src/lib.rs b/klangfarbrs/src/lib.rs
index 4843910..f116430 100644
--- a/klangfarbrs/src/lib.rs
+++ b/klangfarbrs/src/lib.rs
@@ -1,4 +1,10 @@
+use gdnative::api::Resource;
 use gdnative::prelude::*;
+use cpal;
+use cpal::traits::{DeviceTrait, HostTrait, StreamTrait};
+use dasp::{Sample};
+use dasp_signal::{self as signal, Signal};
+use std::sync::mpsc;
 
 /// The HelloWorld "class"
 #[derive(NativeClass)]
@@ -19,6 +25,103 @@ impl HelloWorld {
     }
 }
 
+#[derive(NativeClass)]
+#[inherit(Resource)]
+pub struct Synth {
+    frequency: f32
+}
+
+#[methods]
+impl Synth {
+    #[export]
+    fn set_freq(
+        &mut self,
+        _owner: &Resource,
+        freq: f32
+    ) {
+        self.frequency = freq;
+    }
+
+    #[export]
+    fn _ready(&self, _owner: &Resource) {
+        let host = cpal::default_host();
+        let device = host
+            .default_output_device()
+            .expect("failed to find a default output device");
+        let config = device.default_output_config();
+
+        match config.sample_format() {
+            cpal::SampleFormat::F32 => run::<f32>(&device, &config.into()),
+            cpal::SampleFormat::I16 => run::<i16>(&device, &config.into()),
+            cpal::SampleFormat::U16 => run::<u16>(&device, &config.into()),
+        };
+
+        ();
+    }
+}
+
+fn run<T>(device: &cpal::Device, config: &cpal::StreamConfig) -> Result<(), anyhow::Error>
+where
+    T: cpal::Sample,
+{
+    // Create a signal chain to play back 1 second of each oscillator at A4.
+    let hz = signal::rate(config.sample_rate.0 as f64).const_hz(440.0);
+    let one_sec = config.sample_rate.0 as usize;
+    let mut synth = hz
+        .clone()
+        .sine()
+        .take(one_sec)
+        .chain(hz.clone().saw().take(one_sec))
+        .chain(hz.clone().square().take(one_sec))
+        .chain(hz.clone().noise_simplex().take(one_sec))
+        .chain(signal::noise(0).take(one_sec))
+        .map(|s| s.to_sample::<f32>() * 0.2);
+
+    // A channel for indicating when playback has completed.
+    let (complete_tx, complete_rx) = mpsc::sync_channel(1);
+
+    // Create and run the stream.
+    let err_fn = |err| eprintln!("an error occurred on stream: {}", err);
+    let channels = config.channels as usize;
+    let stream = device.build_output_stream(
+        config,
+        move |data: &mut [T], _: &cpal::OutputCallbackInfo| {
+            write_data(data, channels, &complete_tx, &mut synth)
+        },
+        err_fn,
+    )?;
+    stream.play()?;
+
+    // Wait for playback to complete.
+    complete_rx.recv().unwrap();
+    stream.pause()?;
+
+    Ok(())
+}
+
+fn write_data<T>(
+    output: &mut [T],
+    channels: usize,
+    complete_tx: &mpsc::SyncSender<()>,
+    signal: &mut dyn Iterator<Item = f32>,
+) where
+    T: cpal::Sample,
+{
+    for frame in output.chunks_mut(channels) {
+        let sample = match signal.next() {
+            None => {
+                complete_tx.try_send(()).ok();
+                0.0
+            }
+            Some(sample) => sample,
+        };
+        let value: T = cpal::Sample::from::<f32>(&sample);
+        for sample in frame.iter_mut() {
+            *sample = value;
+        }
+    }
+}
+
 // Function that registers all exposed classes to Godot
 fn init(handle: InitHandle) {
     // Register the new `HelloWorld` type we just declared.
-- 
cgit v1.2.3