three.js/examples/jsm/postprocessing/RenderPass.js

import {
	Color
} from 'three';
import { Pass } from './Pass.js';

class RenderPass extends Pass {

	constructor( scene, camera, overrideMaterial = null, clearColor = null, clearAlpha = null ) {

		super();

		this.scene = scene;
		this.camera = camera;

		this.overrideMaterial = overrideMaterial;

		this.clearColor = clearColor;
		this.clearAlpha = clearAlpha;

		this.clear = true;
		this.clearDepth = false;
		this.needsSwap = false;
		this._oldClearColor = new Color();

	}

	render( renderer, writeBuffer, readBuffer /*, deltaTime, maskActive */ ) {

		const oldAutoClear = renderer.autoClear;
		renderer.autoClear = false;

		let oldClearAlpha, oldOverrideMaterial;

		if ( this.overrideMaterial !== null ) {

			oldOverrideMaterial = this.scene.overrideMaterial;

			this.scene.overrideMaterial = this.overrideMaterial;

		}

		if ( this.clearColor !== null ) {

			renderer.getClearColor( this._oldClearColor );
			renderer.setClearColor( this.clearColor, renderer.getClearAlpha() );

		}

		if ( this.clearAlpha !== null ) {

			oldClearAlpha = renderer.getClearAlpha();
			renderer.setClearAlpha( this.clearAlpha );

		}

		if ( this.clearDepth == true ) {

			renderer.clearDepth();

		}

		renderer.setRenderTarget( this.renderToScreen ? null : readBuffer );

		if ( this.clear === true ) {

			// TODO: Avoid using autoClear properties, see https://github.com/mrdoob/three.js/pull/15571#issuecomment-465669600
			renderer.clear( renderer.autoClearColor, renderer.autoClearDepth, renderer.autoClearStencil );

		}

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

		// restore

		if ( this.clearColor !== null ) {

			renderer.setClearColor( this._oldClearColor );

		}

		if ( this.clearAlpha !== null ) {

			renderer.setClearAlpha( oldClearAlpha );

		}

		if ( this.overrideMaterial !== null ) {

			this.scene.overrideMaterial = oldOverrideMaterial;

		}

		renderer.autoClear = oldAutoClear;

	}

}

export { RenderPass };