three.js/examples/js/postprocessing/TexturePass.js

( function () {

	var TexturePass = function ( map, opacity ) {

		THREE.Pass.call( this );
		if ( THREE.CopyShader === undefined ) console.error( 'THREE.TexturePass relies on THREE.CopyShader' );
		var shader = THREE.CopyShader;
		this.map = map;
		this.opacity = opacity !== undefined ? opacity : 1.0;
		this.uniforms = THREE.UniformsUtils.clone( shader.uniforms );
		this.material = new THREE.ShaderMaterial( {
			uniforms: this.uniforms,
			vertexShader: shader.vertexShader,
			fragmentShader: shader.fragmentShader,
			depthTest: false,
			depthWrite: false
		} );
		this.needsSwap = false;
		this.fsQuad = new THREE.Pass.FullScreenQuad( null );

	};

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

			var oldAutoClear = renderer.autoClear;
			renderer.autoClear = false;
			this.fsQuad.material = this.material;
			this.uniforms[ 'opacity' ].value = this.opacity;
			this.uniforms[ 'tDiffuse' ].value = this.map;
			this.material.transparent = this.opacity < 1.0;
			renderer.setRenderTarget( this.renderToScreen ? null : readBuffer );
			if ( this.clear ) renderer.clear();
			this.fsQuad.render( renderer );
			renderer.autoClear = oldAutoClear;

		}
	} );

	THREE.TexturePass = TexturePass;

} )();