three.js/examples/jsm/nodes/inputs/RTTNode.js

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

import { NodeBuilder } from '../core/NodeBuilder.js';
import { NodeMaterial } from '../materials/NodeMaterial.js';
import { TextureNode } from './TextureNode.js';

function RTTNode( width, height, input, options ) {

	options = options || {};

	this.input = input;

	this.clear = options.clear !== undefined ? options.clear : true;

	this.renderTarget = new WebGLRenderTarget( width, height, options );

	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.render = true;

	TextureNode.call( this, this.renderTarget.texture );

}

RTTNode.prototype = Object.create( TextureNode.prototype );
RTTNode.prototype.constructor = RTTNode;
RTTNode.prototype.nodeType = 'RTT';

RTTNode.prototype.build = function ( builder, output, uuid ) {

	var rttBuilder = new NodeBuilder();
	rttBuilder.nodes = builder.nodes;
	rttBuilder.updaters = builder.updaters;

	this.material.fragment.value = this.input;
	this.material.build( { builder: rttBuilder } );

	return TextureNode.prototype.build.call( this, builder, output, uuid );

};

RTTNode.prototype.updateFramesaveTo = function ( frame ) {

	this.saveTo.render = false;

	if ( this.saveTo !== this.saveToCurrent ) {

		if ( this.saveToMaterial ) this.saveToMaterial.dispose();

		var material = new NodeMaterial();
		material.fragment.value = this;
		material.build();

		var scene = new Scene();

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

		this.saveToScene = scene;
		this.saveToMaterial = material;

	}

	this.saveToCurrent = this.saveTo;

	frame.renderer.setRenderTarget( this.saveTo.renderTarget );
	if ( this.saveTo.clear ) frame.renderer.clear();
	frame.renderer.render( this.saveToScene, this.camera );

};

RTTNode.prototype.updateFrame = function ( frame ) {

	if ( frame.renderer ) {

		// from the second frame

		if ( this.saveTo && this.saveTo.render === false ) {

			this.updateFramesaveTo( frame );

		}

		if ( this.render ) {

			if ( this.material.uniforms.renderTexture ) {

				this.material.uniforms.renderTexture.value = frame.renderTexture;

			}

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

		}

		// first frame

		if ( this.saveTo && this.saveTo.render === true ) {

			this.updateFramesaveTo( frame );

		}

	} else {

		console.warn( 'RTTNode need a renderer in NodeFrame' );

	}

};

RTTNode.prototype.copy = function ( source ) {

	TextureNode.prototype.copy.call( this, source );

	this.saveTo = source.saveTo;

	return this;

};

RTTNode.prototype.toJSON = function ( meta ) {

	var data = this.getJSONNode( meta );

	if ( ! data ) {

		data = TextureNode.prototype.toJSON.call( this, meta );

		if ( this.saveTo ) data.saveTo = this.saveTo.toJSON( meta ).uuid;

	}

	return data;

};

export { RTTNode };