constructor( renderer, outputNode = vec4( 0, 0, 1, 1 ) ) {

		/**
		 * A reference to the renderer.
		 *
		 * @type {Renderer}
		 */
		this.renderer = renderer;

		/**
		 * A node which defines the final output of the post
		 * processing. This is usually the last node in a chain
		 * of effect nodes.
		 *
		 * @type {Node<vec4>}
		 */
		this.outputNode = outputNode;

		/**
		 * Whether the default output tone mapping and color
		 * space transformation should be enabled or not.
		 *
		 * It is enabled by default by it must be disabled when
		 * effects must be executed after tone mapping and color
		 * space conversion. A typical example is FXAA which
		 * requires sRGB input.
		 *
		 * When set to `false`, the app must control the output
		 * transformation with `RenderOutputNode`.
		 *
		 * ```js
		 * const outputPass = renderOutput( scenePass );
		 * ```
		 *
		 * @type {boolean}
		 */
		this.outputColorTransform = true;

		/**
		 * Must be set to `true` when the output node changes.
		 *
		 * @type {Node<vec4>}
		 */
		this.needsUpdate = true;

		const material = new NodeMaterial();
		material.name = 'PostProcessing';

		/**
		 * The full screen quad that is used to render
		 * the effects.
		 *
		 * @private
		 * @type {QuadMesh}
		 */
		this._quadMesh = new QuadMesh( material );

	}
Constructs a new post processing management module.

@param {Renderer} renderer - A reference to the renderer.
@param {Node<vec4>} outputNode - An optional output node.