setupLighting( builder ) {

		const { material } = builder;
		const { backdropNode, backdropAlphaNode, emissiveNode } = this;

		// OUTGOING LIGHT

		const lights = this.lights === true || this.lightsNode !== null;

		const lightsNode = lights ? this.setupLights( builder ) : null;

		let outgoingLightNode = this.setupOutgoingLight( builder );

		if ( lightsNode && lightsNode.getScope().hasLights ) {

			const lightingModel = this.setupLightingModel( builder ) || null;

			outgoingLightNode = lightingContext( lightsNode, lightingModel, backdropNode, backdropAlphaNode );

		} else if ( backdropNode !== null ) {

			outgoingLightNode = vec3( backdropAlphaNode !== null ? mix( outgoingLightNode, backdropNode, backdropAlphaNode ) : backdropNode );

		}

		// EMISSIVE

		if ( ( emissiveNode && emissiveNode.isNode === true ) || ( material.emissive && material.emissive.isColor === true ) ) {

			emissive.assign( vec3( emissiveNode ? emissiveNode : materialEmissive ) );

			outgoingLightNode = outgoingLightNode.add( emissive );

		}

		return outgoingLightNode;

	}
Setups the outgoing light node.

@param {NodeBuilder} builder - The current node builder.
@return {Node<vec3>} The outgoing light node.