ight);

        let directionalLight = new THREE.DirectionalLight("#fff", 0.4);
        directionalLight.position.set(0.5, 0, 0.866);
        scene.add(directionalLight);

        ////////////////////////////////////////////////////////////////////////////////
        //          handle arToolkitSource
        ////////////////////////////////////////////////////////////////////////////////

        const arToolkitSource = new ArToolkitSource({
            sourceType : 'webcam',
            sourceWidth: 480,