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

/**
 * @author alteredq / http://alteredqualia.com/
 */

THREE.TexturePass = function ( texture, opacity ) {

	if ( THREE.CopyShader === undefined )
		console.error( "THREE.TexturePass relies on THREE.CopyShader" );

	var shader = THREE.CopyShader;

	this.uniforms = THREE.UniformsUtils.clone( shader.uniforms );

	this.uniforms[ "opacity" ].value = ( opacity !== undefined ) ? opacity : 1.0;
	this.uniforms[ "tDiffuse" ].value = texture;

	this.material = new THREE.ShaderMaterial( {

		uniforms: this.uniforms,
		vertexShader: shader.vertexShader,
		fragmentShader: shader.fragmentShader

	} );

	this.enabled = true;
	this.needsSwap = false;

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

	this.quad = new THREE.Mesh( new THREE.PlaneBufferGeometry( 2, 2 ), null );
	this.scene.add( this.quad );

};

THREE.TexturePass.prototype = {

	render: function ( renderer, writeBuffer, readBuffer, delta, maskActive ) {

		this.quad.material = this.material;
		this.quad.material.stencilTest = maskActive;

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

	}

};