text: function setup() {
    createCanvas(600, 600);
  }
  
  function draw() {
    background(0);
    var step = 100;
    
    for (var j = 0; j < height; j += step) {
      for (var i = 0; i < width; i += step) {
        var tx = i+step*0.5;
        var ty = j+step*0.5;
        var radius = sin((millis()*0.0005)*PI+(i/width+j/height))*step;
        // var radius = sin((millis()*0.0005)*PI*(i/width+j/height))*step;
        ellipse(tx, ty, radius, radius);
      }
    }
  }