text: var a, b;
  var w, h;
  var theta = 0;
  var phi = 0;
  
  function setup() {
    createCanvas(600, 600, WEBGL);
    setAttributes('antialias', true);
    strokeWeight(2);
  }
  
  function draw() {
    background(230);
  
    // Draws dividers between rotating quadrants.
    stroke(237, 34, 93);
    a = 425 * cos(theta);
    b = 425 * sin(theta);
    line(-a, -b, a, b);
    line(-b, a, b, -a);
  
    // Should draw a growing/shrinking ellipse with alternating colour in
    // each quadrant.
    w = 300 + 250 * cos(phi);
    h = 300 + 250 * sin(phi);
    noStroke();
    fill(255);
    arc(0, 0, w, h, theta, theta + PI / 2);
    arc(0, 0, w, h, theta + PI, theta + 3 * PI / 2);
    fill(200);
    arc(0, 0, w, h, theta + PI / 2, theta + PI);
    arc(0, 0, w, h, theta + 3 * PI / 2, theta);
  
    theta += 0.01;
    phi += 0.0123;
  }
  