@thi.ng/dsp/waveshaper.js

Composable signal generators, oscillators, filters, FFT, spectrum, windowing & related DSP utils

import { PI } from "@thi.ng/math/api";
import { AProc } from "./aproc.js";
const waveShaper = (thresh, amp, map) => new WaveShaper(thresh, amp, map);
class WaveShaper extends AProc {
  constructor(_coeff = 3, amp = true, _map = waveshapeSigmoid) {
    super(0);
    this._coeff = _coeff;
    this._map = _map;
    amp === true ? this.setAutoGain() : this.setAmp(amp);
  }
  _amp;
  _autoGain;
  next(x) {
    return this._val = this._amp * this._map(x, this._coeff);
  }
  coeff() {
    return this._coeff;
  }
  setCoeff(t) {
    this._coeff = Math.max(t, 0);
    this._autoGain && this.setAutoGain();
  }
  amp() {
    return this._amp;
  }
  setAmp(a) {
    this._amp = a;
    this._autoGain = false;
  }
  setAutoGain() {
    this._amp = 1 / this._map(1, this._coeff);
    this._autoGain = true;
  }
}
const waveshapeTan = (x, k) => Math.atan(k * x) / k;
const waveshapeSigmoid = (x, k) => 2 / (1 + Math.exp(-k * x)) - 1;
const waveshapeSin = (x, k) => Math.sin(PI / k * x);
export {
  WaveShaper,
  waveShaper,
  waveshapeSigmoid,
  waveshapeSin,
  waveshapeTan
};