For shadows to work
  renderer.shadowMap.enabled = true;
  renderer.shadowMap.type = THREE.PCFSoftShadowMap;

  // The materials in Poly models will render as a black mesh
  // without lights in our scenes. Let's add an ambient light
  // so our model can be scene, as well as a directional light
  // for the shadow
  directionalLight = new THREE.DirectionalLight();
  // @TODO in the future, use AR light estimation
  directionalLight.intensity = 0.3;
  directionalLight.position.set(10, 15, 10);
  // We want 