How to apply multiple shaders to one 3D object, using Three.js and WebGL

I'm playing around with WebGL. The following is a working example with a 3D object using Three.js. Is it possible to add multiple shaders to one 3D object, like this one? It would be highly appreciated if you can share some knowledge.

I just learned from one pro that helped with solutions to applying one shader material to 3D object. However, I'm curious about whether to add multiple shaders to give more effects to the 3D object.

<!DOCTYPE html>
<html lang="en">
    <head>
        <title>OBJ loader</title>
        <meta charset="utf-8">
        <meta name="viewport" content="width=device-width, user-scalable=no, minimum-scale=1.0, maximum-scale=1.0">
        <style>
            body {
                font-family: Monospace;
                background-color: #fff;
                color: #fff;
                margin: 0px;
                overflow: hidden;
            }
            #info {
                color: #fff;
                position: absolute;
                top: 10px;
                width: 100%;
                text-align: center;
                z-index: 100;
                display:block;
            }
            #info a, .button { color: #f00; font-weight: bold; text-decoration: underline; cursor: pointer }
        </style>
    </head>

    <body>


        <script src="http://threejs.org/build/three.min.js"></script>
        <script src="http://threejs.org/examples/js/loaders/OBJLoader.js"></script>

        <script src="http://threejs.org/examples/js/libs/stats.min.js"></script>

        <script>
            var clock = new THREE.Clock();
            var delta = clock.getDelta(); // seconds.
            var rotateAngle = Math.PI / 2 * delta;   // pi/2 radians (90 degrees) per second
            var container, stats;

            var camera, scene, renderer, texture;

            var mouseX = 0, mouseY = 0;

            var windowHalfX = window.innerWidth / 2;
            var windowHalfY = window.innerHeight / 2;

            init();
            animate();
    //var texture = new THREE.Texture();
                new THREE.OBJLoader( ).load( 'https://s3-us-west-2.amazonaws.com/s.cdpn.io/40480/head.obj', function ( object ) {

                    object.traverse( function ( child ) {

                        if ( child instanceof THREE.Mesh ) {

                            child.material.map = texture;

                        }

                    } );

    
                  
                    scene.add( object );

                } );

            function init() {

                container = document.createElement( 'div' );
                document.body.appendChild( container );

                camera = new THREE.PerspectiveCamera( 15, window.innerWidth / window.innerHeight, 1, 2000 );
                camera.position.z = 100;

                // scene

                scene = new THREE.Scene();

                var ambient = new THREE.AmbientLight( 0x111130 );
                scene.add( ambient );

                var directionalLight = new THREE.DirectionalLight( 0xffeeff );
                directionalLight.position.set( 1, 1,0.5 );
                scene.add( directionalLight );

    
        

                renderer = new THREE.WebGLRenderer();
                renderer.setSize( window.innerWidth, window.innerHeight );
                container.appendChild( renderer.domElement );

                document.addEventListener( 'mousemove', onDocumentMouseMove, false );

                window.addEventListener( 'resize', onWindowResize, false );

            }

            function onWindowResize() {
                windowHalfX = window.innerWidth / 2;
                windowHalfY = window.innerHeight / 2;

                camera.aspect = window.innerWidth / window.innerHeight;
                camera.updateProjectionMatrix();

                renderer.setSize( window.innerWidth, window.innerHeight );
            }

            function onDocumentMouseMove( event ) {
                mouseX = ( event.clientX - windowHalfX ) / 2;
                mouseY = ( event.clientY - windowHalfY ) / 2;
            }

            function animate() {
                requestAnimationFrame( animate );
                render();
            }

            function render() {
             

                camera.position.x += ( mouseX - camera.position.x ) * .05;
                camera.position.y += ( - mouseY - camera.position.y ) * .05;

                camera.lookAt( scene.position );

                renderer.render( scene, camera );
            }
        </script>
    </body>
</html>

Solution

In general, rendering a mesh with multiple materials is possible in three.js if the geometry defines proper groups data. However you normally render different parts of the mesh with distinct materials. E.g. when having a character model, you would render the skin with one material and the cloths with a different one.

You don't want to use this approach to combine or stack effects. Instead, you have to implement a single custom shader that includes all effects that you want to apply on the surface.