Tone.js/Tone/instrument/NoiseSynth.ts

import { AmplitudeEnvelope } from "../component/envelope/AmplitudeEnvelope";
import { NormalRange, Time } from "../core/type/Units";
import { omitFromObject, optionsFromArguments } from "../core/util/Defaults";
import { RecursivePartial } from "../core/util/Interface";
import { Noise, NoiseOptions } from "../source/Noise";
import { Instrument, InstrumentOptions } from "./Instrument";
import { ToneAudioNode, ToneAudioNodeOptions } from "../core/context/ToneAudioNode";
import { Envelope, EnvelopeOptions } from "../component/envelope/Envelope";
import { Source } from "../source/Source";

export interface NoiseSynthOptions extends InstrumentOptions {
	envelope: Omit<EnvelopeOptions, keyof ToneAudioNodeOptions>;
	noise: Omit<NoiseOptions, keyof ToneAudioNodeOptions>;
}

/**
 * Tone.NoiseSynth is composed of [[Noise]] through an [[AmplitudeEnvelope]]. 
 * ```
 * +-------+   +-------------------+
 * | Noise +>--> AmplitudeEnvelope +>--> Output
 * +-------+   +-------------------+
 * ```
 * @example
 * const noiseSynth = new Tone.NoiseSynth().toDestination();
 * noiseSynth.triggerAttackRelease("8n", 0.05);
 * @category Instrument
 */
export class NoiseSynth extends Instrument<NoiseSynthOptions> {

	readonly name = "NoiseSynth";

	/**
	 * The noise source.
	 */
	readonly noise: Noise;

	/**
	 * The amplitude envelope.
	 */
	readonly envelope: AmplitudeEnvelope;

	constructor(options?: RecursivePartial<NoiseSynthOptions>)
	constructor() {
		super(optionsFromArguments(NoiseSynth.getDefaults(), arguments));
		const options = optionsFromArguments(NoiseSynth.getDefaults(), arguments);
		this.noise = new Noise(Object.assign({
			context: this.context,
		}, options.noise));

		this.envelope = new AmplitudeEnvelope(Object.assign({
			context: this.context,
		}, options.envelope));

		// connect the noise to the output
		this.noise.chain(this.envelope, this.output);
	}

	static getDefaults(): NoiseSynthOptions {
		return Object.assign(Instrument.getDefaults(), {
			envelope: Object.assign(
				omitFromObject(Envelope.getDefaults(), Object.keys(ToneAudioNode.getDefaults())),
				{
					decay: 0.1,
					sustain: 0.0,
				},
			),
			noise: Object.assign(
				omitFromObject(Noise.getDefaults(), Object.keys(Source.getDefaults())),
				{
					type: "white",
				},
			),
		});
	}

	/**
	 * Start the attack portion of the envelopes. Unlike other
	 * instruments, Tone.NoiseSynth doesn't have a note.
	 * @example
	 * const noiseSynth = new Tone.NoiseSynth().toDestination();
	 * noiseSynth.triggerAttack();
	 */
	triggerAttack(time?: Time, velocity: NormalRange = 1): this {
		time = this.toSeconds(time);
		// the envelopes
		this.envelope.triggerAttack(time, velocity);
		// start the noise
		this.noise.start(time);
		if (this.envelope.sustain === 0) {
			this.noise.stop(time + this.toSeconds(this.envelope.attack) + this.toSeconds(this.envelope.decay));
		}
		return this;
	}

	/**
	 * Start the release portion of the envelopes.
	 */
	triggerRelease(time?: Time): this {
		time = this.toSeconds(time);
		this.envelope.triggerRelease(time);
		this.noise.stop(time + this.toSeconds(this.envelope.release));
		return this;
	}

	sync(): this {
		this._syncMethod("triggerAttack", 0);
		this._syncMethod("triggerRelease", 0);
		return this;
	}

	triggerAttackRelease(duration: Time, time?: Time, velocity: NormalRange = 1): this {
		time = this.toSeconds(time);
		duration = this.toSeconds(duration);
		this.triggerAttack(time, velocity);
		this.triggerRelease(time + duration);
		return this;
	}

	dispose(): this {
		super.dispose();
		this.noise.dispose();
		this.envelope.dispose();
		return this;
	}
}