					if ( ! params.useBVH ) {

						geometry.boundsTree = null;

					}

					scene.add( mesh );
					mesh.scale.setScalar( 0.0075 );

					helper = new MeshBVHHelper( mesh );
					helper.color.set( 0xE91E63 );
					scene.add( helper );

				} );

				const controls = new OrbitControls( camera, renderer.domElement );
				controls.minDistance = 5;
				controls.maxDistance = 75;

				// set up gui
				const gui = new GUI();
				const rayFolder = gui.addFolder( 'Raycasting' );
				rayFolder.add( params, 'coun