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examples(webaudio): Tidy up the webaudio example

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This commit is contained in:
Nick Fitzgerald
2018-09-10 17:50:34 -07:00
parent e730ee9a62
commit 42ea38187f
5 changed files with 79 additions and 80 deletions
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80
examples/webaudio/src/lib.rs
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@ -2,7 +2,9 @@ extern crate wasm_bindgen;
extern crate web_sys;
use wasm_bindgen::prelude::*;
use web_sys::{AudioContext, BaseAudioContext, AudioNode, AudioScheduledSourceNode, OscillatorType};
use web_sys::{
AudioContext, AudioNode, AudioScheduledSourceNode, BaseAudioContext, OscillatorType,
};
/// Converts a midi note to frequency
///
@ -32,16 +34,12 @@ pub struct FmOsc {
fm_freq_ratio: f32,
fm_gain_ratio: f32,
}
#[wasm_bindgen]
impl FmOsc {
#[wasm_bindgen(constructor)]
pub fn new() -> FmOsc {
// TODO, how to throw from a constructor?
let ctx = web_sys::AudioContext::new().unwrap();
let primary;
let fm_osc;
@ -51,14 +49,14 @@ impl FmOsc {
{
let base: &BaseAudioContext = ctx.as_ref();
// create our web audio objects
// Create our web audio objects.
primary = base.create_oscillator().unwrap();
fm_osc = base.create_oscillator().unwrap();
gain = base.create_gain().unwrap();
fm_gain = base.create_gain().unwrap();
}
// some initial settings:
// Some initial settings:
primary.set_type(OscillatorType::Sine);
primary.frequency().set_value(440.0); // A4 note
gain.gain().set_value(0.0); // starts muted
@ -66,7 +64,6 @@ impl FmOsc {
fm_osc.set_type(OscillatorType::Sine);
fm_osc.frequency().set_value(0.0);
// Create base class references:
{
let primary_node: &AudioNode = primary.as_ref();
@ -77,26 +74,36 @@ impl FmOsc {
let destination = base.destination();
let destination_node: &AudioNode = destination.as_ref();
// Connect the nodes up!
// connect them up:
// The primary oscillator is routed through the gain node, so that it can control the overall output volume
// The primary oscillator is routed through the gain node, so that
// it can control the overall output volume.
primary_node.connect_with_audio_node(gain.as_ref()).unwrap();
// Then connect the gain node to the AudioContext destination (aka your speakers)
// Then connect the gain node to the AudioContext destination (aka
// your speakers).
gain_node.connect_with_audio_node(destination_node).unwrap();
// the FM oscillator is connected to its own gain node, so it can control the amount of modulation
fm_osc_node.connect_with_audio_node(fm_gain.as_ref()).unwrap();
// The FM oscillator is connected to its own gain node, so it can
// control the amount of modulation.
fm_osc_node
.connect_with_audio_node(fm_gain.as_ref())
.unwrap();
// Connect the FM oscillator to the frequency parameter of the main oscillator, so that the
// FM node can modulate its frequency
fm_gain_node.connect_with_audio_param(&primary.frequency()).unwrap();
// Connect the FM oscillator to the frequency parameter of the main
// oscillator, so that the FM node can modulate its frequency.
fm_gain_node
.connect_with_audio_param(&primary.frequency())
.unwrap();
}
// start the oscillators!
AsRef::<AudioScheduledSourceNode>::as_ref(&primary).start().unwrap();
AsRef::<AudioScheduledSourceNode>::as_ref(&fm_osc).start().unwrap();
// Start the oscillators!
AsRef::<AudioScheduledSourceNode>::as_ref(&primary)
.start()
.unwrap();
AsRef::<AudioScheduledSourceNode>::as_ref(&fm_osc)
.start()
.unwrap();
FmOsc {
ctx,
@ -107,14 +114,17 @@ impl FmOsc {
fm_freq_ratio: 0.0,
fm_gain_ratio: 0.0,
}
}
/// Sets the gain for this oscillator, between 0.0 and 1.0
/// Sets the gain for this oscillator, between 0.0 and 1.0.
#[wasm_bindgen]
pub fn set_gain(&self, mut gain: f32) {
if gain > 1.0 { gain = 1.0; }
if gain < 0.0 { gain = 0.0; }
if gain > 1.0 {
gain = 1.0;
}
if gain < 0.0 {
gain = 0.0;
}
self.gain.gain().set_value(gain);
}
@ -122,11 +132,10 @@ impl FmOsc {
pub fn set_primary_frequency(&self, freq: f32) {
self.primary.frequency().set_value(freq);
// The frequency of the FM oscillator depends on the frequency of the primary oscillator, so
// we update the frequency of both in this method
// The frequency of the FM oscillator depends on the frequency of the
// primary oscillator, so we update the frequency of both in this method.
self.fm_osc.frequency().set_value(self.fm_freq_ratio * freq);
self.fm_gain.gain().set_value(self.fm_gain_ratio * freq);
}
#[wasm_bindgen]
@ -135,21 +144,22 @@ impl FmOsc {
self.set_primary_frequency(freq);
}
/// This should be between 0 and 1, though higher values are accepted
/// This should be between 0 and 1, though higher values are accepted.
#[wasm_bindgen]
pub fn set_fm_amount(&mut self, amt: f32) {
self.fm_gain_ratio = amt;
self.fm_gain.gain().set_value(self.fm_gain_ratio * self.primary.frequency().value());
self.fm_gain
.gain()
.set_value(self.fm_gain_ratio * self.primary.frequency().value());
}
/// This should be between 0 and 1, though higher values are accepted
/// This should be between 0 and 1, though higher values are accepted.
#[wasm_bindgen]
pub fn set_fm_frequency(&mut self, amt: f32) {
self.fm_freq_ratio = amt;
self.fm_osc.frequency().set_value(self.fm_freq_ratio * self.primary.frequency().value());
self.fm_osc
.frequency()
.set_value(self.fm_freq_ratio * self.primary.frequency().value());
}
}