1.创建场景
var scene = new THREE.Scene();
scene.background = new THREE.Color('#ac9e83'); //设置背景色
2.创建正交投影照相机
var camera = new THREE.PerspectiveCamera(75, window.innerWidth / window.innerHeight, 0.1, 1000);
camera.position.set( 0 , -10, 0 );
camera.lookAt(scene.position);
