40ac7256f3
Introduces SynthEngine interface so additive/FM engines can be hot-swapped later. C15Bridge is wrapped by C15Adapter; arpeggiator decoupled from SAB.
120 lines
2.8 KiB
JavaScript
120 lines
2.8 KiB
JavaScript
// Arpeggiator — plays chord progressions through any SynthEngine.
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// Delegates to a dedicated Web Worker for reliable timing.
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// The worker posts noteOn/noteOff messages back to the main thread, which
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// forwards them through the active SynthEngine. This keeps the arpeggiator
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// decoupled from C15's SharedArrayBuffer ring buffer so any engine works.
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export class Arpeggiator {
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/**
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* @param {import('./engine-interface.js').SynthEngine} engine
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*/
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constructor(engine) {
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this.engine = engine;
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this._worker = null;
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this._playing = false;
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this._bpm = 120;
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this._octaves = 2;
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this._octaveOffset = 0;
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this._progression = 'Cmin7-rand';
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this._direction = 'updown';
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}
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get progressionNames() {
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return ['Cmin7-rand', 'I-vi-IV-V', 'I-IV-vi-V', 'i-VI-III-VII', 'I-V-vi-IV'];
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}
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get directionNames() {
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return ['up', 'updown'];
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}
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get playing() { return this._playing; }
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get bpm() { return this._bpm; }
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set bpm(v) {
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this._bpm = v;
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this._send('set', { bpm: v });
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}
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get octaves() { return this._octaves; }
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set octaves(v) {
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this._octaves = v;
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this._send('set', { octaves: v });
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}
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get octaveOffset() { return this._octaveOffset; }
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set octaveOffset(v) {
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this._octaveOffset = v;
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this._send('set', { octaveOffset: v });
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}
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get progression() { return this._progression; }
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set progression(v) {
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this._progression = v;
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this._send('set', { progression: v });
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}
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get direction() { return this._direction; }
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set direction(v) {
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this._direction = v;
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this._send('set', { direction: v });
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}
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_ensureWorker() {
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if (this._worker) return;
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this._worker = new Worker(
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new URL('./arpeggiator-worker.js', import.meta.url),
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{ type: 'module' }
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);
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this._worker.onmessage = (e) => {
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const { type, data } = e.data;
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switch (type) {
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case 'state':
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this._playing = data.playing;
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break;
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case 'noteOn':
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this.engine.noteOn(data.note, data.velocity);
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break;
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case 'noteOff':
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this.engine.noteOff(data.note);
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break;
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}
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};
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// Sync current settings to worker
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this._send('set', {
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bpm: this._bpm,
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octaves: this._octaves,
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octaveOffset: this._octaveOffset,
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progression: this._progression,
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direction: this._direction,
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});
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}
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_send(type, data) {
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if (this._worker) {
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this._worker.postMessage({ type, data });
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}
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}
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start() {
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this._ensureWorker();
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this._send('start');
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this._playing = true; // optimistic, worker confirms
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}
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stop() {
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this._send('stop');
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this._playing = false;
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}
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/**
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* Hot-swap the engine without restarting the worker.
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* Called by setActiveEngine() in a-app.js.
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* @param {import('./engine-interface.js').SynthEngine} engine
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*/
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setEngine(engine) {
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this.engine = engine;
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}
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}
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