HTML5：THREE.JS 新手遇到了问题，求帮忙！

</body><script>    var camera, scene, renderer, geometry, material, mesh;    init();    animate();    function init(){        renderer = new THREE.WebGLRenderer();        renderer.setSize(640, 480);        camera = new THREE.PerspectiveCamera(55, 640/480, 1, 10000);        camera.position.z = 1000;                scene = new THREE.Scene();        geometry = new THREE.Geometry();        geometry.vertices.push(new THREE.Vector3(-200, -200, 200));        geometry.vertices.push(new THREE.Vector3(200, -200, 200));        geometry.vertices.push(new THREE.Vector3(200, 200, 200));        geometry.vertices.push(new THREE.Vector3(-200, 200, 200));        geometry.vertices.push(new THREE.Vector3(-200, -200, -200));        geometry.vertices.push(new THREE.Vector3(-200, 200, -200));        geometry.vertices.push(new THREE.Vector3(200, -200, -200));        geometry.vertices.push(new THREE.Vector3(200, 200, -200));        geometry.vertices.push(new THREE.Vector3(-200,200,-200));        geometry.vertices.push(new THREE.Vector3(-200,200,200));        geometry.vertices.push(new THREE.Vector3(200,200,200));        geometry.vertices.push(new THREE.Vector3(200,200,-200));        geometry.vertices.push(new THREE.Vector3(-200,-200,-200));        geometry.vertices.push(new THREE.Vector3(200,-200,-200));        geometry.vertices.push(new THREE.Vector3(200,-200,200));        geometry.vertices.push(new THREE.Vector3(-200,-200,200));        geometry.vertices.push(new THREE.Vector3(200,-200,-200));        geometry.vertices.push(new THREE.Vector3(200,200,-200));        geometry.vertices.push(new THREE.Vector3(200,200,200));        geometry.vertices.push(new THREE.Vector3(200,-200,200));        geometry.vertices.push(new THREE.Vector3(-200,-200,-200));        geometry.vertices.push(new THREE.Vector3(-200,-200,200));        geometry.vertices.push(new THREE.Vector3(-200,200,200));        geometry.vertices.push(new THREE.Vector3(-200,200,-200));        geometry.faces.push(new THREE.Face3(0,1,2));        geometry.faces.push(new THREE.Face3(0,2,3));        geometry.faces.push(new THREE.Face3(4,5,6));        geometry.faces.push(new THREE.Face3(4,6,7));        geometry.faces.push(new THREE.Face3(8,9,10));        geometry.faces.push(new THREE.Face3(8,10,11));        geometry.faces.push(new THREE.Face3(12,13,14));        geometry.faces.push(new THREE.Face3(12,14,15));        geometry.faces.push(new THREE.Face3(16,17,18));        geometry.faces.push(new THREE.Face3(16,18,19));        geometry.faces.push(new THREE.Face3(20,21,22));        geometry.faces.push(new THREE.Face3(20,22,23));        var textureCoords = [            0.0, 0.0,            1.0, 0.0,            1.0, 1.0,            0.0, 1.0,            1.0, 0.0,            1.0, 1.0,            0.0, 1.0,            0.0, 0.0,            0.0, 1.0,            0.0, 0.0,            1.0, 0.0,            1.0, 1.0,            1.0, 1.0,            0.0, 1.0,            0.0, 0.0,            1.0, 0.0,            1.0, 0.0,            1.0, 1.0,            0.0, 1.0,            0.0, 0.0,            0.0, 0.0,            1.0, 0.0,            1.0, 1.0,            0.0, 1.0,        ]        for (var i = 0; i < geometry.faces.length; i++){            var uva = new THREE.Vector2(textureCoords[geometry.faces[i]['a']*2],textureCoords[geometry.faces[i]['a']*2+1]);            var uvb = new THREE.Vector2(textureCoords[geometry.faces[i]['b']*2],textureCoords[geometry.faces[i]['b']*2+1]);            var uvc = new THREE.Vector2(textureCoords[geometry.faces[i]['c']*2],textureCoords[geometry.faces[i]['c']*2+1]);            geometry.faceVertexUvs[0].push([uva,uvb,uvc]);                    }        var material = new THREE.MeshBasicMaterial({color: 0xff0000, wireframe: true});        mesh = new THREE.Mesh(geometry, material);        scene.add(mesh);        var dom=document.createElement('canvas');        document.body.appendChild(dom);        }    function animate() {        requestAnimationFrame(animate);        mesh.rotation.x += 0.01;        mesh.rotation.y += 0.02;        renderer.render(scene, camera);    }</script>

爲什麽我执行这段码什麽事情都没发生？？