let bin = [0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0];

​

function setup() {

  createCanvas(400, 400);

  inp = createP('');

  let btn = createButton('clear');

  btn.mousePressed(function(){

      bin = [0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0];

  });

}

​

​

function draw() {

  inp.html(binToHex(bin));

​

  background(0);

  for (let x = 0; x < 4; x++) {

    for (let y = 0; y < 4; y++) {

      if (bin[x + y * 4] == 1) {

        fill(255, 0, 255);

        rect(x * 100, y * 100, 100, 100);

      }

    }

  }

}

​

function mouseClicked() {

  if (mouseX > 400 || mouseY > 400) return;

  let x = floor(mouseX / 100);

  let y = floor(mouseY / 100);

  bin[x + y * 4] = (bin[x + y * 4] + 1) % 2;

}

​

function binToHex(binary) {

  return parseInt(binary.join(''), 2).toString(16);

}