参考: http://www.yanhuangxueyuan.com/Three.js_course/camera.html
//创建场景对象
var scene = new THREE.Scene();
//创建一个立方体几何对象
var box = new THREE.BoxGeometry(100, 100, 100);
//材质对象
var material = new THREE.MeshLambertMaterial({
color: 0x0000ff,
opacity: 0.5,
transparent: true
});
//网格模型对象
var mesh = new THREE.Mesh(box, material);
//网格模型添加到场景中
scene.add(mesh);
//点光源
var point = new THREE.PointLight(0xffffff);
//点光源位置
point.position.set(400, 200, 300);
//点光源添加到场景中
scene.add(point);
//环境光
var ambient=new THREE.AmbientLight(0x444444);
scene.add(ambient);
var width = window.innerWidth;
var height = window.innerHeight;
//窗口宽高比
var k = width / height;
//三维场景缩放系数
var