text: function setup() {
      var cnv = createCanvas(windowWidth, windowHeight);
      var x = (windowWidth - width) / 2;
      var y = (windowHeight - height) / 2;
      cnv.position(x, y);
      frameRate(30);
      noStroke();
      colorMode(HSB, 255);
  }
  // track time
  var frame = 0;
  // constants
  var degree = Math.PI / 180;
  var slice = 2 * (Math.PI / 3);
  
  function draw() {
      // reset background and update angle
      background(0);
      var angle = (frame++) * degree;
      // draw 3 rotating slices
      fill(frame % 255, 255, 255);
      arc(width / 2, height / 2, width, height, slice + angle, (2 * slice) + angle, PIE);
      fill((frame + 85) % 255, 255, 255);
      arc(width / 2, height / 2, width, height, (2 * slice) + angle, (3 * slice) + angle, PIE);
      fill((frame + 170) % 255, 255, 255);
      arc(width / 2, height / 2, width, height, (3 * slice) + angle, (4 * slice) + angle, PIE);
  }