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

( function () {

	var RenderPass = function ( scene, camera, overrideMaterial, clearColor, clearAlpha ) {

		THREE.Pass.call( this );
		this.scene = scene;
		this.camera = camera;
		this.overrideMaterial = overrideMaterial;
		this.clearColor = clearColor;
		this.clearAlpha = clearAlpha !== undefined ? clearAlpha : 0;
		this.clear = true;
		this.clearDepth = false;
		this.needsSwap = false;
		this._oldClearColor = new THREE.Color();

	};

	RenderPass.prototype = Object.assign( Object.create( THREE.Pass.prototype ), {
		constructor: RenderPass,
		render: function ( renderer, writeBuffer, readBuffer
			/*, deltaTime, maskActive */
		) {

			var oldAutoClear = renderer.autoClear;
			renderer.autoClear = false;
			var oldClearAlpha, oldOverrideMaterial;

			if ( this.overrideMaterial !== undefined ) {

				oldOverrideMaterial = this.scene.overrideMaterial;
				this.scene.overrideMaterial = this.overrideMaterial;

			}

			if ( this.clearColor ) {

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

			}

			if ( this.clearDepth ) {

				renderer.clearDepth();

			}

			renderer.setRenderTarget( this.renderToScreen ? null : readBuffer ); // TODO: Avoid using autoClear properties, see https://github.com/mrdoob/three.js/pull/15571#issuecomment-465669600

			if ( this.clear ) renderer.clear( renderer.autoClearColor, renderer.autoClearDepth, renderer.autoClearStencil );
			renderer.render( this.scene, this.camera );

			if ( this.clearColor ) {

				renderer.setClearColor( this._oldClearColor, oldClearAlpha );

			}

			if ( this.overrideMaterial !== undefined ) {

				this.scene.overrideMaterial = oldOverrideMaterial;

			}

			renderer.autoClear = oldAutoClear;

		}
	} );

	THREE.RenderPass = RenderPass;

} )();