this light to cast shadow
  directionalLight.castShadow = true;
  light = new THREE.AmbientLight();
  scene.add(light);
  scene.add(directionalLight);

  // Make a large plane to receive our shadows
  planeGeometry = new THREE.PlaneGeometry(2000, 2000);
  // Rotate our plane to be parallel to the floor
  planeGeometry.rotateX(-Math.PI / 2);

  // Create a mesh with a shadow material, resulting in a mesh
  // that only renders shadows once we flip the `receiveShadow` property
  shadowMesh = new THREE.Mesh(pl