ce, so that the
  // perspective camera's depth planes and field of view matches
  // the physical camera on the device.
  camera = new THREE.ARPerspectiveCamera(
    vrDisplay,
    60,
    window.innerWidth / window.innerHeight,
    vrDisplay.depthNear,
    vrDisplay.depthFar
  );

  // VRControls is a utility from three.js that applies the device's
  // orientation/position to the perspective camera, keeping our
  // real world and virtual world in sync.
  vrControls = new THREE.VRControls(camera);

  // 