three.js/examples/jsm/nodes/postprocessing/NodePostProcessing.js

import {
	LinearFilter,
	Mesh,
	OrthographicCamera,
	PlaneGeometry,
	RGBAFormat,
	Scene,
	Vector2,
	WebGLRenderTarget
} from '../../../../build/three.module.js';

import { NodeMaterial } from '../materials/NodeMaterial.js';
import { ScreenNode } from '../inputs/ScreenNode.js';

function NodePostProcessing( renderer, renderTarget ) {

	if ( renderTarget === undefined ) {

		var parameters = {
			minFilter: LinearFilter,
			magFilter: LinearFilter,
			format: RGBAFormat
		};

		var size = renderer.getDrawingBufferSize( new Vector2() );
		renderTarget = new WebGLRenderTarget( size.width, size.height, parameters );

	}

	this.renderer = renderer;
	this.renderTarget = renderTarget;

	this.output = new ScreenNode();
	this.material = new NodeMaterial();

	this.camera = new OrthographicCamera( - 1, 1, 1, - 1, 0, 1 );
	this.scene = new Scene();

	this.quad = new Mesh( new PlaneGeometry( 2, 2 ), this.material );
	this.quad.frustumCulled = false; // Avoid getting clipped
	this.scene.add( this.quad );

	this.needsUpdate = true;

}

NodePostProcessing.prototype = {

	constructor: NodePostProcessing,

	render: function ( scene, camera, frame ) {

		if ( this.needsUpdate ) {

			this.material.dispose();

			this.material.fragment.value = this.output;
			this.material.build();

			if ( this.material.uniforms.renderTexture ) {

				this.material.uniforms.renderTexture.value = this.renderTarget.texture;

			}

			this.needsUpdate = false;

		}

		frame.setRenderer( this.renderer )
			.setRenderTexture( this.renderTarget.texture );

		this.renderer.setRenderTarget( this.renderTarget );
		this.renderer.render( scene, camera );

		frame.updateNode( this.material );

		this.renderer.setRenderTarget( null );
		this.renderer.render( this.scene, this.camera );

	},

	setPixelRatio: function ( value ) {

		this.renderer.setPixelRatio( value );

		var size = this.renderer.getSize( new Vector2() );

		this.setSize( size.width, size.height );

	},

	setSize: function ( width, height ) {

		var pixelRatio = this.renderer.getPixelRatio();

		this.renderTarget.setSize( width * pixelRatio, height * pixelRatio );

		this.renderer.setSize( width, height );

	},

	copy: function ( source ) {

		this.output = source.output;

		return this;

	},

	toJSON: function ( meta ) {

		var isRootObject = ( meta === undefined || typeof meta === 'string' );

		if ( isRootObject ) {

			meta = {
				nodes: {}
			};

		}

		if ( meta && ! meta.post ) meta.post = {};

		if ( ! meta.post[ this.uuid ] ) {

			var data = {};

			data.uuid = this.uuid;
			data.type = 'NodePostProcessing';

			meta.post[ this.uuid ] = data;

			if ( this.name !== '' ) data.name = this.name;

			if ( JSON.stringify( this.userData ) !== '{}' ) data.userData = this.userData;

			data.output = this.output.toJSON( meta ).uuid;

		}

		meta.post = this.uuid;

		return meta;

	}

};

export { NodePostProcessing };