showDebugLightmap( visible, position = undefined ) {

			if ( this.lightMapContainers.length == 0 ) {

				if ( ! this.warned ) {

					console.warn( 'Call this after adding the objects!' );
					this.warned = true;

				}

				return;

			}

			if ( this.labelMesh == null ) {

				this.labelMaterial = new THREE.MeshBasicMaterial( {
					map: this.progressiveLightMap1.texture,
					side: THREE.DoubleSide
				} );
				this.labelPlane = new THREE.PlaneGeometry( 100, 100 );
				this.labelMesh = new THREE.Mesh( this.labelPlane, this.labelMaterial );
				this.labelMesh.position.y = 250;
				this.lightMapContainers[ 0 ].object.parent.add( this.labelMesh );

			}

			if ( position != undefined ) {

				this.labelMesh.position.copy( position );

			}

			this.labelMesh.visible = visible;

		}
DEBUG
Draw the lightmap in the main scene.  Call this after adding the objects to it.
@param {boolean} visible Whether the debug plane should be visible
@param {Vector3} position Where the debug plane should be drawn