showDebugLightmap( visible, position = undefined ) {

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

			console.warn( 'THREE.ProgressiveLightMap: Call .showDebugLightmap() after adding the objects.' );

			return;

		}

		if ( this.labelMesh === null ) {

			const labelMaterial = new MeshBasicMaterial( { map: this.progressiveLightMap1.texture, side: DoubleSide } );
			const labelGeometry = new PlaneGeometry( 100, 100 );
			this.labelMesh = new Mesh( labelGeometry, 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;

	}
Draws 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