velocity-for-color.js

// velocity-for-color
// https://github.com/brunchboy/afterglow/blob/master/src/afterglow/controllers/ableton_push.clj#L24
module.exports = (h, s, v) => {
  if (v < 3) {
    return 0;
  }

  const brightnessShift = (60 < v) ? 0 : (37 < v) ? 1 : (15 < v) ? 2 : 3;

  if (s < 20) {
    return Math.min(4 - brightnessShift, 3);
  }

  const baseHue = h;
  const adjustedHue = baseHue > 230 ? Math.min(baseHue * 1.2, 360) : baseHue;
  const hueSection = 4 + 4 * Math.floor(13 * adjustedHue / 360);

  return hueSection + brightnessShift;
};