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/**
* Relabi event generator
*/
import * as Tone from "tone";
import RelabiCanvas from "./canvas";
const TWO_PI = 2 * Math.PI;
/**
* Wave functions
*/
const WAVE_FUNCTIONS = {
sine: Math.cos,
triangle: (time) =>
(4 / TWO_PI) *
Math.abs(
((((time - TWO_PI / 4) % TWO_PI) + TWO_PI) % TWO_PI) - TWO_PI / 2
) -
1,
square: (time) => (time % TWO_PI < Math.PI ? 1 : -1),
saw: (time) => ((time % TWO_PI) - Math.PI) / Math.PI,
};
/**
* Relabi generator
*/
export default class Relabi {
/**
* Initialize generator
*/
constructor({ waves, bounds, parent }) {
this.updateTime = 1;
this.steps = 50;
this.waves = waves || [
{ type: "triangle", frequency: randrange(0.5, 1.5) },
{ type: "triangle", frequency: randrange(0.75, 2.25) },
{ type: "triangle", frequency: randrange(1, 3) },
{ type: "triangle", frequency: randrange(2, 4) },
];
this.bounds = bounds;
this.previousValue = null;
this.canvas = new RelabiCanvas({ relabi: this, parent });
}
/**
* Start the generator
*/
start() {
console.log("Start Relabi");
this.stop();
this.clock = new Tone.Clock((time) => {
const values = this.generate(time);
const notes = this.play(values);
this.canvas.append(time, values, notes);
}, this.updateTime);
this.clock.start();
}
/**
* Stop the generator and reset it
*/
stop() {
if (this.clock) {
this.clock.stop();
this.clock.dispose();
}
}
/**
* Generate relabi events
*/
generate(time) {
const waveCount = this.waves.length;
let index;
let step;
let value;
let values = [];
// Overshoot the line slightly each time
let stepCount = this.steps + 20;
// Generate several events per second
for (step = 0; step < stepCount; step += 1) {
// Time offset for this event
const timeOffset = time + (step * this.updateTime) / this.steps;
// Initialize value
value = 0;
// Compute the wave functions for this event
for (index = 0; index < waveCount; index += 1) {
const wave = this.waves[index];
value += WAVE_FUNCTIONS[wave.type](timeOffset * wave.frequency);
}
// Scale to [-1, 1]
value /= waveCount;
values.push([timeOffset, value]);
}
return values;
}
/**
* Schedule relabi events
*/
play(values) {
const boundsCount = this.bounds.length;
let previousValue = this.previousValue;
let index;
let step;
let noteCount = 0;
const notes = [];
for (step = 0; step < this.steps; step += 1) {
// Get the next value
const [time, value] = values[step];
// Compute whether we crossed a boundary, and which direction
for (index = 0; index < boundsCount; index += 1) {
const bound = this.bounds[index];
if (
value < bound.level &&
bound.level < previousValue &&
previousValue !== null
) {
// Going down
this.trigger(time, bound.sounds[0]);
notes.push([time, bound.level, true]);
noteCount += 1;
} else if (
value > bound.level &&
bound.level > previousValue &&
previousValue !== null
) {
// Going up
this.trigger(time, bound.sounds[1]);
notes.push([time, bound.level, false]);
noteCount += 1;
}
}
// Update the previous value
previousValue = value;
}
// Store the latest value
this.previousValue = previousValue;
// Return the notes
return notes;
}
/**
* Trigger an event
*/
trigger(time, sound) {
// console.log("trigger index", index, time);
sound.instrument.play(time, sound);
}
}
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