How to use the three.Group function in three

addVertices(rightArm2Box, toSkinVertices(44, 32, 47, 36), toSkinVertices(47, 32, 50, 36), toSkinVertices(40, 36, 44, 48), toSkinVertices(44, 36, 47, 48), toSkinVertices(47, 36, 51, 48), toSkinVertices(51, 36, 54, 48));
		} else {
			addVertices(rightArm2Box, toSkinVertices(44, 32, 48, 36), toSkinVertices(48, 32, 52, 36), toSkinVertices(40, 36, 44, 48), toSkinVertices(44, 36, 48, 48), toSkinVertices(48, 36, 52, 48), toSkinVertices(52, 36, 56, 48));
		}
		var rightArm2Mesh = new Mesh(rightArm2Box, layer2Material);
		rightArm2Mesh.renderOrder = 1;
		rightArmPivot.add(rightArm2Mesh);

		rightArmPivot.position.y = -6;
		_this.rightArm.add(rightArmPivot);
		_this.rightArm.position.y = -4;
		_this.rightArm.position.x = slim ? -5.5 : -6;
		_this.add(_this.rightArm);

		// Left Arm
		_this.leftArm = new Group();
		var leftArmPivot = new Group();

		var leftArmBox = new BoxGeometry((slim ? 3 : 4) - esp, 12 - esp, 4 - esp, 0, 0, 0);
		if (slim) {
			addVertices(leftArmBox, toSkinVertices(36, 48, 39, 52), toSkinVertices(39, 48, 42, 52), toSkinVertices(32, 52, 36, 64), toSkinVertices(36, 52, 39, 64), toSkinVertices(39, 52, 43, 64), toSkinVertices(43, 52, 46, 64));
		} else {
			addVertices(leftArmBox, toSkinVertices(36, 48, 40, 52), toSkinVertices(40, 48, 44, 52), toSkinVertices(32, 52, 36, 64), toSkinVertices(36, 52, 40, 64), toSkinVertices(40, 52, 44, 64), toSkinVertices(44, 52, 48, 64));
		}
		var leftArmMesh = new Mesh(leftArmBox, layer1Material);
		leftArmPivot.add(leftArmMesh);

		var leftArm2Box = new BoxGeometry((slim ? 3.375 : 4.5) - esp, 13.5 - esp, 4.5 - esp, 0, 0, 0);
		if (slim) {
			addVertices(leftArm2Box, toSkinVertices(52, 48, 55, 52), toSkinVertices(55, 48, 58, 52), toSkinVertices(48, 52, 52, 64), toSkinVertices(52, 52, 55, 64), toSkinVertices(55, 52, 59, 64), toSkinVertices(59, 52, 62, 64));
		} else {
			addVertices(leftArm2Box, toSkinVertices(52, 48, 56, 52), toSkinVertices(56, 48, 60, 52), toSkinVertices(48, 52, 52, 64), toSkinVertices(52, 52, 56, 64), toSkinVertices(56, 52, 60, 64), toSkinVertices(60, 52, 64, 64));

_updateMeshes(previousGroup?: Group) {
    if (!this._objState) {
      return;
    }
    const fallbackMaterial = this._lit
      ? this._litMaterial
      : this._unlitMaterial;
    const group = previousGroup || new Group();
    let index = 0;
    this._objState.objects.forEach(obj => {
      const geometry = obj.geometry;
      if (geometry.position.length < 1) {
        return;
      }
      const materials = obj.materials
        // Eliminate materials that don't have any faces
        .filter(m => m.startGroup < m.endGroup || m.endGroup < 0);
      const bufferGeometry = previousGroup ? null : new BufferGeometry();
      if (bufferGeometry) {
        bufferGeometry.addAttribute(
          'position',
          new BufferAttribute(new Float32Array(geometry.position), 3),
        );
        bufferGeometry.setIndex(

constructor(options = {}) {
    super();
    this.vizWrapper = new Group$1();
    this.add(this.vizWrapper);

    this.stats = new Stats();
    this.stats.showPanel(0);

    this.initLights();
    this.initGrid();
    this.updateOptions(options);
  }

parse(data, mtllibCallback) {
    let faceOffset = 0;
    const group = new THREE.Group();
    let object = group;

    let geometry = new THREE.Geometry();
    let material = new THREE.MeshLambertMaterial();
    let mesh = new THREE.Mesh(geometry, material);

    let vertices = [];
    const normals = [];
    const uvs = [];

    function vector(x, y, z) {
      return new THREE.Vector3(x, y, z);
    }

    function uv(u, v) {
      return new THREE.Vector2(u, v);

for ( var i = 0, l = instanceNodes.length; i < l; i ++ ) {

				objects.push( getNode( instanceNodes[ i ] ).clone() );

			}

			var object;

			if ( nodes.length === 0 && objects.length === 1 ) {

				object = objects[ 0 ];

			} else {

				object = ( type === 'JOINT' ) ? new THREE.Bone() : new THREE.Group();

				for ( var i = 0; i < objects.length; i ++ ) {

					object.add( objects[ i ] );

				}

			}

			if ( object.name === '' ) {

				object.name = ( type === 'JOINT' ) ? data.sid : data.name;

			}

			object.matrix.copy( matrix );

MeshCreator.prototype.setSceneGraphBaseNode = function ( sceneGraphBaseNode ) {
			this.sceneGraphBaseNode = Validator.verifyInput( sceneGraphBaseNode, this.sceneGraphBaseNode );
			this.sceneGraphBaseNode = Validator.verifyInput( this.sceneGraphBaseNode, new THREE.Group() );
		};

scene.add(challenge2)
  challenges.push(challenge2)

  const challenge3 = addChallenge(3, -100, 2, -20)
  scene.add(challenge3)
  challenges.push(challenge3)

  const challenge4 = addChallenge(10, 0, 2, -20)
  scene.add(challenge4)
  challenges.push(challenge4)

  const challenge5 = addChallenge(5, 100, 2, -71)
  scene.add(challenge5)
  challenges.push(challenge5)

  const stars = new THREE.Group()
  const geometry = new THREE.SphereGeometry(10, 3, 3)
  const material = new THREE.MeshBasicMaterial({
    color: 0xA9D9E5,
    wireframe: false,
  })

  const radius = 2500
  const separation = 3

  for (let i = 0 + separation; i <= 180 - separation; i += separation) {
    const radian1 = i * Math.PI / 180

    for (let j = 0; j < 360; j += separation) {
      const radian2 = j * Math.PI / 180

      const cube = new THREE.Mesh(geometry, material)

function drawParticles() {
    particles = new THREE.Group();
    scene.add(particles);
    const geometry = new THREE.TetrahedronGeometry(2, 0);

    for (let i = 0; i < 500; i++) {
      const material = new THREE.MeshPhongMaterial({
        color: 0x9CE7EA,
        shading: THREE.FlatShading
      });
      const mesh = new THREE.Mesh(geometry, material);
      mesh.position.set((Math.random() - 0.5) * 1000,
        (Math.random() - 0.5) * 1000,
        (Math.random() - 0.5) * 1000);
      mesh.updateMatrix();
      mesh.matrixAutoUpdate = false;
      particles.add(mesh);
    }

constructor(scene, config, font, antique, emitter) {
    this.emitter = emitter;
    this.scene = scene;
    this.font = font;
    this.config = config;
    this.wrap = wrap(CHAR_LIMIT);
    this.buttons = {};
    this.antique = antique;
    this.messageGroup = new Group();
    this.intersectedButton = null;
    this.scene.add(this.messageGroup);
    this.setMessage('waiting');
    this.showMessage();
    this.crazyGroup = new Group();
    this.scene.add(this.crazyGroup);
    this.buttons[config.rainbowText] = new Button(this.crazyGroup, this.font, config.rainbowText, 0, 2, this.emitter, 0.7 * 100, 0.2 * 100, 0.01 * 100, 0.04 * 100);
    this.buttons[config.rainbowText].buttonGroup.position.z = 200;
    this.buttons[config.rainbowText].buttonGroup.rotation.y = Math.PI;
  }