let step = 1;

​

function preload() {

  img = loadImage('pattern1.jpg');

}

​

function setup() {

  createCanvas(400, 400);

}

​

function draw() {

  background(255);

  drawPattern(step);

}

​

function drawPattern(currentStep) {

  loadPixels();

  for (let x = 0; x < width; x++) {

    for (let y = 0; y < height; y++) {

      let index = (x + y * width) * 4;

      let brightnessValue = brightness(img.get(x, y));

      if (brightnessValue > map(currentStep, 0, 10, 0, 255)) {

        stroke(0);

        point(x, y);

      }

    }

  }

}

​

function mousePressed() {

  if (step < 10) {

    step++;

    redraw();

  }

}

​

​