let osn;

let w = 5;

function setup() {

  createCanvas(500, 500);

  osn = new OpenSimplexNoise(99);

}

​

function draw() {

  let cols = width / w;

  let rows = height / w;

  let xoff = 0;

  for (let i = 0; i < cols; i++) {

    let yoff = 0;

    for (let j = 0; j < rows; j++) {

      noStroke();

      let r = osn.noise3D(xoff, yoff, zoff) * 127 + 127;

      let g = osn.noise3D(yoff, xoff, zoff) * 127 + 127;

      let b = osn.noise3D(zoff, xoff, yoff) * 127 + 127;

      fill(r, g, b);

      square(i * w, j * w, w);

      yoff += 0.1;

    }

    xoff += 0.01;

  }

  zoff += 0.01;

}

​