Based on Rectangles 2 by @b2renger:

https://github.com/b2renger/p5js_patterns/blob/master/rectangles_2/sketch.js

*/

​

let size;

let randomVal;

let round;

let step = 0.05;

​

function setup() {

  createCanvas(windowWidth, windowHeight);

  background(0);

  rectMode(CENTER);

  randomVal = random(1000);

  size = min(width / 20, height / 20);

  round = random(size / 2);

}

​

function draw() {

  background(0);

  randomVal += step;

  fill(255);

  for (let x = size; x < windowWidth - size; x += size) {

    for (let y = size; y < windowHeight - size; y += size) {

      let n = noise(randomVal, x / 120, y / 430) * size;

      let round = noise(randomVal / 2, x / 50, y / 100) * (size / 4);

      rect(x, y, n, n, round);

    }

  }

}

​

function mouseReleased() {

  randomVal = random(1000);

  step = random(100) / 1000;

}

​

function windowResized() {

  resizeCanvas(windowWidth, windowHeight);

  size = min(width / 20, height / 20);

}

​