three.js/examples/jsm/webxr/XRHandMeshModel.js

import { GLTFLoader } from '../loaders/GLTFLoader.js';

class XRHandMeshModel {

	constructor( handModel, controller, assetUrl ) {

		this.controller = controller;
		this.handModel = handModel;

		this.bones = [];
		const loader = new GLTFLoader();

		loader.setPath( '' );
		loader.load( assetUrl, gltf => {

			const object = gltf.scene.children[ 0 ];
			this.handModel.add( object );

			const mesh = object.getObjectByProperty( 'type', 'SkinnedMesh' );
			mesh.frustumCulled = false;
			mesh.castShadow = true;
			mesh.receiveShadow = true;

			const joints = [
				'wrist',
				'thumb-metacarpal',
				'thumb-phalanx-proximal',
				'thumb-phalanx-distal',
				'thumb-tip',
				'index-finger-metacarpal',
				'index-finger-phalanx-proximal',
				'index-finger-phalanx-intermediate',
				'index-finger-phalanx-distal',
				'index-finger-tip',
				'middle-finger-metacarpal',
				'middle-finger-phalanx-proximal',
				'middle-finger-phalanx-intermediate',
				'middle-finger-phalanx-distal',
				'middle-finger-tip',
				'ring-finger-metacarpal',
				'ring-finger-phalanx-proximal',
				'ring-finger-phalanx-intermediate',
				'ring-finger-phalanx-distal',
				'ring-finger-tip',
				'pinky-finger-metacarpal',
				'pinky-finger-phalanx-proximal',
				'pinky-finger-phalanx-intermediate',
				'pinky-finger-phalanx-distal',
				'pinky-finger-tip',
			];

			joints.forEach( jointName => {

				const bone = object.getObjectByName( jointName );
				if ( bone !== undefined ) {

					bone.jointName = jointName;

				} else {

					console.warn( `Couldn't find ${jointName} in ${handedness} hand mesh` );

				}

				this.bones.push( bone );

			} );

		} );

	}

	updateMesh() {

		// XR Joints
		const XRJoints = this.controller.joints;
		for ( let i = 0; i < this.bones.length; i ++ ) {

			const bone = this.bones[ i ];
			if ( bone ) {

				const XRJoint = XRJoints[ bone.jointName ];
				if ( XRJoint.visible ) {

					const position = XRJoint.position;
					if ( bone ) {

						bone.position.copy( position );
						bone.quaternion.copy( XRJoint.quaternion );
						// bone.scale.setScalar( XRJoint.jointRadius || defaultRadius );

					}

				}

			}

		}

	}

}

export { XRHandMeshModel };