​

function getPixelID(x, y, g) {

  let _density;

  if (g == null) _density = pixelDensity();

  else _density = g.pixelDensity();

​

  const idx = 4 * _density * (int(y) * _density * width + int(x));

  return idx;

}

​

let off;

function setup() {

  createCanvas(1000, 1000);

  pixelDensity(1);

  background(20);

  loadPixels();

  for (let y = 0; y < height; y++) {

    for (let x = 0; x < width; x++) {

      let c = color(220);

      if (x <= 5 || y <= 5 || x >= width-6 || y >= height-6) c = color(0,0,255);

      else if (x % 2 == 0) c = color(255,0,255);

      else if (y % 2 == 0) c = color(0,0,255);

      let idx = getPixelID(x,y,null);

      pixels[idx] = red(c);

      pixels[idx+1] = green(c);

      pixels[idx+2] = blue(c);

    }

  }

  updatePixels();

}

​

function draw() {

  // background(220);

}