for sorting
			elem.style.zIndex = ( - tempV.z * .5 + .5 ) * 100000 | 0;

		}

	}

	class GPUPickHelper {

		constructor() {

			// create a 1x1 pixel render target
			this.pickingTexture = new THREE.WebGLRenderTarget( 1, 1 );
			this.pixelBuffer = new Uint8Array( 4 );

		}
		pick( cssPosition, scene, camera ) {

			const { pickingTexture, pixelBuffer } = this;

			// set the view offset to represent just a single pixel under the mouse
			const pixelRatio = renderer.getPixelRatio();
			camera.setViewOffset(