Three.js PointLight无法正常工作

Question

我已经对Three.js库进行了一些测试，看了一下docs，并想出了一个创建一个盒子的简单脚本。一切都很好，直到这里。然后我试着添加一盏灯，它只是没有照亮我的盒子。 脚本：

    var scene = new THREE.Scene();
    var camera = new THREE.PerspectiveCamera(90, window.innerWidth / window.innerHeight, 0.1, 1000);
    var geometry = new THREE.BoxGeometry( 1, 1, 1 );
    var material = new THREE.MeshBasicMaterial({ color: 0x000066 });
    var cube = new THREE.Mesh(geometry, material);
    scene.add(new THREE.AmbientLight(0x404040, 0.9));
    var pointLight = new THREE.PointLight(0xFFFFFF, 1, 100);
    pointLight.position.x = 0;
    pointLight.position.y = 10;
    pointLight.position.z = 0;
    scene.add(pointLight);
    scene.add(cube);
    camera.position.z = 4;
    camera.position.y = 1;
    var renderer = new THREE.WebGLRenderer();
    renderer.setSize(window.innerWidth, window.innerHeight);
    document.body.appendChild(renderer.domElement);
    animate();
    function animate() {
        requestAnimationFrame(animate);
        render();

    }
    function render(){
        renderer.render(scene, camera);
    }

如何显示：

帮助！