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121 lines
3.4 KiB
JavaScript
121 lines
3.4 KiB
JavaScript
import { getAudioContext } from './superdough.mjs';
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// https://github.com/KilledByAPixel/ZzFX/blob/master/ZzFX.js#L85C5-L180C6
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// changes: replaced this.volume with 1 + using sampleRate from getAudioContext()
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export function buildSamples(
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volume = 1,
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randomness = 0.05,
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frequency = 220,
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attack = 0,
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sustain = 0,
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release = 0.1,
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shape = 0,
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shapeCurve = 1,
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slide = 0,
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deltaSlide = 0,
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pitchJump = 0,
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pitchJumpTime = 0,
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repeatTime = 0,
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noise = 0,
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modulation = 0,
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bitCrush = 0,
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delay = 0,
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sustainVolume = 1,
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decay = 0,
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tremolo = 0,
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) {
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// init parameters
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let PI2 = Math.PI * 2,
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sampleRate = getAudioContext().sampleRate,
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sign = (v) => (v > 0 ? 1 : -1),
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startSlide = (slide *= (500 * PI2) / sampleRate / sampleRate),
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startFrequency = (frequency *= ((1 + randomness * 2 * Math.random() - randomness) * PI2) / sampleRate),
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b = [],
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t = 0,
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tm = 0,
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i = 0,
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j = 1,
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r = 0,
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c = 0,
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s = 0,
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f,
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length;
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// scale by sample rate
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attack = attack * sampleRate + 9; // minimum attack to prevent pop
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decay *= sampleRate;
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sustain *= sampleRate;
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release *= sampleRate;
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delay *= sampleRate;
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deltaSlide *= (500 * PI2) / sampleRate ** 3;
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modulation *= PI2 / sampleRate;
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pitchJump *= PI2 / sampleRate;
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pitchJumpTime *= sampleRate;
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repeatTime = (repeatTime * sampleRate) | 0;
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// generate waveform
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for (length = (attack + decay + sustain + release + delay) | 0; i < length; b[i++] = s) {
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if (!(++c % ((bitCrush * 100) | 0))) {
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// bit crush
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s = shape
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? shape > 1
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? shape > 2
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? shape > 3 // wave shape
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? Math.sin((t % PI2) ** 3) // 4 noise
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: Math.max(Math.min(Math.tan(t), 1), -1) // 3 tan
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: 1 - (((((2 * t) / PI2) % 2) + 2) % 2) // 2 saw
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: 1 - 4 * Math.abs(Math.round(t / PI2) - t / PI2) // 1 triangle
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: Math.sin(t); // 0 sin
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s =
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(repeatTime
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? 1 - tremolo + tremolo * Math.sin((PI2 * i) / repeatTime) // tremolo
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: 1) *
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sign(s) *
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Math.abs(s) ** shapeCurve * // curve 0=square, 2=pointy
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volume *
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1 * // envelope
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(i < attack
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? i / attack // attack
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: i < attack + decay // decay
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? 1 - ((i - attack) / decay) * (1 - sustainVolume) // decay falloff
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: i < attack + decay + sustain // sustain
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? sustainVolume // sustain volume
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: i < length - delay // release
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? ((length - i - delay) / release) * // release falloff
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sustainVolume // release volume
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: 0); // post release
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s = delay
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? s / 2 +
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(delay > i
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? 0 // delay
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: ((i < length - delay ? 1 : (length - i) / delay) * // release delay
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b[(i - delay) | 0]) /
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2)
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: s; // sample delay
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}
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f =
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(frequency += slide += deltaSlide) * // frequency
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Math.cos(modulation * tm++); // modulation
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t += f - f * noise * (1 - (((Math.sin(i) + 1) * 1e9) % 2)); // noise
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if (j && ++j > pitchJumpTime) {
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// pitch jump
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frequency += pitchJump; // apply pitch jump
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startFrequency += pitchJump; // also apply to start
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j = 0; // stop pitch jump time
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}
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if (repeatTime && !(++r % repeatTime)) {
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// repeat
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frequency = startFrequency; // reset frequency
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slide = startSlide; // reset slide
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j ||= 1; // reset pitch jump time
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}
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}
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return b;
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}
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