hree.js virtual scene
  renderer.clearDepth();
  renderer.render(scene, camera);

  // Kick off the requestAnimationFrame to call this function
  // when a new VRDisplay frame is rendered
  vrDisplay.requestAnimationFrame(update);
}

/**
 * On window resize, update the perspective camera's aspect ratio,
 * and call `updateProjectionMatrix` so that we can get the latest
 * projection matrix provided from the device
 */
function onWindowResize () {
  camera.aspect = window.innerWidth / window.innerHeight;
  c