spotlight

HTML

<div id="info">spotlight demo
    <br/>Press Z to toggle</div>
<script src="http://cdnjs.cloudflare.com/ajax/libs/three.js/r70/three.min.js"></script>
<script src="https://dl.dropboxusercontent.com/u/3587259/Code/Threejs/OrbitControls.js">
    
</script>
<script src="http://jyunming-chen.github.io/tutsplus/js/KeyboardState.js"></script>

CSS

#info {
    position: absolute;
    top: 0px;
    width: 100%;
    padding: 10px;
    text-align: center;
    color: #ffff00
}
body {
    // margin: 0;
    overflow: hidden;
}

JavaScript

var camera, scene, renderer, geometry, material, mesh, light, controls;
var rt, alpha, h, ly;
var box, angle = 0;
var keyboard = new KeyboardState(), turn = true;

init();
animate();

function init() {
    scene = new THREE.Scene();

    camera = new THREE.PerspectiveCamera(50, window.innerWidth / window.innerHeight, 1, 1000);
    camera.position.z = 500;
    scene.add(camera);

    // lamp parameters
    ly = 150;
    rt = 30;
    h = 140;
    alpha = Math.PI / 8;
    var rb = rt + h * Math.tan(alpha);

    geometry = new THREE.CylinderGeometry(rt, rb, h, 20, 1, true);
    material = new THREE.MeshBasicMaterial({
        side: THREE.DoubleSide,
        wireframe: true,
        color: 0xffff00
    });
    mesh = new THREE.Mesh(geometry, material);
    mesh.position.setY(-h / 2); // so that top face is on XZ plane

    lamp = new THREE.Object3D();
    lamp.add(mesh);
    lamp.position.setY(ly);
    scene.add(lamp);

    // orbiting box
    box = new THREE.Mesh(new THREE.BoxGeometry(20, 20, 20),
                         new THREE.MeshLambertMaterial({color:0xff1234}));
    scene.add(box);

    // spotlight
    light = new THREE.SpotLight(0xffffff, 1.5);
    light.position.set(0, ly, 0);
    light.angle = alpha;
    light.exponent = 10;
    scene.add(light);
    light.target = box; // light follows the box

    // floor
    var floor = new THREE.Mesh(new THREE.PlaneGeometry(400, 400, 30, 30),
    new THREE.MeshLambertMaterial());
    floor.rotation.x = -Math.PI / 2;
    scene.add(floor);

    var amblight = new THREE.AmbientLight(0x888888); // soft white light
    scene.add(amblight);

    renderer = new THREE.WebGLRenderer();
    renderer.setSize(window.innerWidth, window.innerHeight);
    renderer.setClearColor(0x333333);

    controls = new THREE.OrbitControls(camera, renderer.domElement);

    document.body.appendChild(renderer.domElement);
}

function animate() {
    controls.update();
    keyboard.update();
    
    if (keyboard.down("Z")) turn = !turn;
    if...