datamosh/lib/modes/veneneux.js

Edit images via buffers.

"use strict";

module.exports = function (data, width, height) {
  const rand = Math.random;
  const max = Math.max;

  function giveSeed() {
    const seed = [0, 0, 0];

    const ind1 = Math.floor(rand() * 3);
    const ind2 = Math.floor(rand() * 3);

    seed[ind1] = max(rand(), 0.1);
    if (rand() > 0.5) seed[ind2] = max(rand(), 0.1);

    return seed;
  }

  let pixel = 0;
  let seed = giveSeed();
  let seedChange = 2;

  for (let i = 0; i < data.length; i += 4) {
    if (pixel % (width * 4) === 0) {
      seedChange--;
      if (seedChange === 0) {
        seed = giveSeed();
        seedChange = Math.floor((rand() * height) / 4);
      }
    }

    data[i + 0] = (data[i + 0] * seed[0] + 1000 * seed[2]) % 256;
    data[i + 1] = (data[i + 1] * seed[1] + 1000 * seed[1]) % 256;
    data[i + 2] = (data[i + 2] * seed[2] + 1000 * seed[0]) % 256;
    data[i + 3] = rand() * 256 - 1;

    pixel++;
  }

  return data;
};