// The Coding Train / Daniel Shiffman

// https://thecodingtrain.com/challenges/179-wolfram-ca

// https://youtu.be/Ggxt06qSAe4

​

let cells = [];

let ruleSet;

let w = 4;

let startRule = 90;

let palette = [];

let y = 0;

​

function setRules(ruleValue) {

  ruleSet = ruleValue.toString(2);

  while (ruleSet.length < 8) {

    ruleSet = "0" + ruleSet;

  }

}

​

function setup() {

  createCanvas(500, 500);

  setRules(startRule);

  palette = [

    color(11, 106, 136),

    color(25, 297, 244),

    color(112, 50, 126),

    color(146, 83, 161),

    color(164, 41, 99),

    color(236, 1, 90),

    color(240, 99, 164),

    color(241, 97, 100),

    color(248, 158, 79),

  ];

​

  let total = width / w;

  for (let i = 0; i < total; i++) {

    cells[i] = random(palette);

  }

  background(255);

}

​

function draw() {

  for (let i = 0; i < cells.length; i++) {

    let x = i * w;

    noStroke();

    fill(cells[i]);

    square(x, y, w);

  }

​

  y += w;

  if (y > height) {

    background(255);

    y = 0;

    setRules(floor(random(256)));

  }

​

  let nextCells = [];

  let len = cells.length;

  for (let i = 0; i < cells.length; i++) {

    let leftColor = cells[(i - 1 + len) % len];

    let rightColor = cells[(i + 1 + len) % len];

    let stateColor = cells[i];

    let left = brightness(leftColor) < 100 ? 1 : 0;

    let right = brightness(rightColor) < 100 ? 1 : 0;

    let state = brightness(stateColor) < 100 ? 1 : 0;

    let newState = calculateState(left, state, right);

    if (newState == 0) {

      nextCells[i] = color(255);

    } else {

      let options = [];

      if (left == 1) options.push(leftColor);

      if (right == 1) options.push(rightColor);

      if (state == 1) options.push(stateColor);

      if (options.length < 1) nextCells[i] = random(palette);

      else nextCells[i] = random(options);

    }

  }

​

  cells = nextCells; 

}

​

function calculateState(a, b, c) {

  let neighborhood = "" + a + b + c;

  let value = 7 - parseInt(neighborhood, 2);

  return parseInt(ruleSet[value]);

}

​