getDepthNode() {

		if ( this._depthNode === null ) {

			if ( this._reflectorBaseNode.depth !== true ) {

				throw new Error( 'THREE.ReflectorNode: Depth node can only be requested when the reflector is created with { depth: true }. ' );

			}

			this._depthNode = nodeObject( new ReflectorNode( {
				defaultTexture: _defaultRT.depthTexture,
				reflector: this._reflectorBaseNode
			} ) );

		}

		return this._depthNode;

	}
Returns a node representing the mirror's depth. That can be used
to implement more advanced reflection effects like distance attenuation.

@return {Node} The depth node.