constructor( mesh ) {

			const shadowMaterial = new THREE.MeshBasicMaterial( {
				color: 0x000000,
				transparent: true,
				opacity: 0.6,
				depthWrite: false
			} );
			super( mesh.geometry, shadowMaterial );
			this.meshMatrix = mesh.matrixWorld;
			this.frustumCulled = false;
			this.matrixAutoUpdate = false;

		}
A shadow THREE.Mesh that follows a shadow-casting THREE.Mesh in the scene, but is confined to a single plane.