function setup() {

  createCanvas(windowWidth,

               windowHeight);

  background(300, 300, 300);

}



function draw() {

  var from = color(100, 200, 300);

  var to = color(200, 500, 150);



  for (var i = 0.0; i < width; i = i + 30.0) {

    for (var j = 0.0; j < height; j = j + 30.0) {

      stroke(300);

      fill(lerpColor(from, to, (i + j) / (width + height)));

      rect(i, j, 30, 30);

    }



  }

}