​

function setup() {

  createCanvas(500, 400);

  //pixelDensity(1); // fix for high density displays

}

​

function draw() {

  loadPixels();

  let d = pixelDensity();

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

    for (let x = 0; x < width * d; x++) {

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

      // Red.

      pixels[index] = x;

      // Green.

      pixels[index + 1] = y;

      // Blue.

      pixels[index + 2] = random(x, y);

      // Alpha.

      pixels[index + 3] = 255;

    }

  }

  updatePixels();

}

​