Three.js 3D特效学习

一、Three.js基本介绍

Three.js是JavaScript编写的WebGL第三方库。提供了非常多的3D显示功能。Three.js 是一款运行在浏览器中的 3D 引擎，你可以用它创建各种三维场景，包括了摄影机、光影、材质等各种对象。你可以在它的主页上看到许多精采的演示。不过，这款引擎目前还处在比较不成熟的开发阶段，其不够丰富的 API 以及匮乏的文档增加了初学者的学习难度（尤其是文档的匮乏，基本没有中文的）Three.js的代码托管在github上面。

二、基本 Demo

1.最基本的Hello World：http://stemkoski.github.io/Three.js/HelloWorld.html

2.在网页上调用摄像头：http://stemkoski.github.io/Three.js/Webcam-Texture.html

3.体感操作：http://stemkoski.github.io/Three.js/Webcam-Motion-Detection-Texture.html

4.支持游戏手柄：http://stemkoski.github.io/Three.js/Mesh-Movement-Gamepad.html

5.3D建模和方向键控制移动方向：http://stemkoski.github.io/Three.js/Model-Animation-Control.html

6.SkyBox和三个气泡的渲染：http://stemkoski.github.io/Three.js/Metabubbles.html

7.3D红蓝偏光的名车展：http://threejs.org/examples/webgl_materials_cars_anaglyph.html

8.跑车游戏：http://hexgl.bkcore.com/

三、Three.js编写环境准备

1.Three.js库文件下载：https://github.com/mrdoob/three.js/

2.已安装IIS或Tomcat或Apache，这些例子必须挂到服务器上才能正常运行，本地打开会出现各种无法理解的问题。

四、动手编写第一个 Demo

<!doctype html>
<html lang="en">
<head>
<title>Template (Three.js)</title>
<meta charset="utf-8">
<meta name="viewport"
    content="width=device-width, user-scalable=no, minimum-scale=1.0, maximum-scale=1.0">
<link rel=stylesheet href="css/base.css" />
</head> 

<body>
    <script src="../js/Three.js"></script> <!-- 这个是Three.js引擎的js -->
    <script src="../js/Detector.js"></script>
    <script src="../js/Stats.js"></script>
    <script src="../js/OrbitControls.js"></script>
    <script src="../js/THREEx.KeyboardState.js"></script>
    <script src="../js/THREEx.FullScreen.js"></script>
    <script src="../js/THREEx.WindowResize.js"></script>
    <script src="../js/Texture.js"></script> <!-- 一些js工具类，现在不深究 --> 

    <div id="ThreeJS"
        style="z-index: 1; position: absolute; left: 0px; top: 0px"></div> <!-- 这个div就是整个画布 -->
    <script>
        //////////
        // MAIN //
        //////////
        // standard global variables
        var container, scene, camera, renderer, controls, stats; // 几个变量代表的含义：容器、场景、摄像机（视角）、渲染器、控制装置
        var keyboard = new THREEx.KeyboardState();
        var clock = new THREE.Clock(); 

        // custom global variables
        var cube; 

        // initialization
        init(); 

        // animation loop / game loop
        animate(); 

        ///////////////
        // FUNCTIONS //
        /////////////// 

        function init() { // 初始化
            ///////////
            // SCENE //
            ///////////
            scene = new THREE.Scene(); // 定义场景 

            ////////////
            // CAMERA //
            //////////// 

            // set the view size in pixels (custom or according to window size)
            // var SCREEN_WIDTH = 400, SCREEN_HEIGHT = 300;
            var SCREEN_WIDTH = window.innerWidth, SCREEN_HEIGHT = window.innerHeight;
            // camera attributes
            var VIEW_ANGLE = 45, ASPECT = SCREEN_WIDTH / SCREEN_HEIGHT, NEAR = 0.1, FAR = 20000;
            // set up camera
            camera = new THREE.PerspectiveCamera(VIEW_ANGLE, ASPECT, NEAR, FAR); // 定义视角
            // add the camera to the scene
            scene.add(camera);
            // the camera defaults to position (0,0,0)
            // so pull it back (z = 400) and up (y = 100) and set the angle towards the scene origin
            camera.position.set(-400, 150, 200); // 视角的位置
            camera.lookAt(scene.position); 

            //////////////
            // RENDERER //
            ////////////// 

            // create and start the renderer; choose antialias setting.
            if (Detector.webgl)
                renderer = new THREE.WebGLRenderer({
                    antialias : true
                });
            else
                renderer = new THREE.CanvasRenderer(); 

            renderer.setSize(SCREEN_WIDTH, SCREEN_HEIGHT); 

            // attach div element to variable to contain the renderer
            container = document.getElementById('ThreeJS');
            // alternatively: to create the div at runtime, use:
            // container = document.createElement( 'div' );
            // document.body.appendChild( container ); 

            // attach renderer to the container div
            container.appendChild(renderer.domElement); 

            ////////////
            // EVENTS //
            //////////// 

            // automatically resize renderer
            THREEx.WindowResize(renderer, camera);
            // toggle full-screen on given key press
            THREEx.FullScreen.bindKey({
                charCode : 'm'.charCodeAt(0)
            }); 

            //////////////
            // CONTROLS //
            ////////////// 

            // move mouse and: left   click to rotate,
            //                 middle click to zoom,
            //                 right  click to pan
            controls = new THREE.OrbitControls(camera, renderer.domElement); // 设置控制，这里只有鼠标操作 

            ///////////
            // STATS //
            /////////// 

            // displays current and past frames per second attained by scene
            stats = new Stats();
            stats.domElement.style.position = 'absolute';
            stats.domElement.style.bottom = '0px';
            stats.domElement.style.zIndex = 100;
            container.appendChild(stats.domElement); 

            ///////////
            // LIGHT //
            /////////// 

            // create a light
            var light = new THREE.PointLight(0xffffff); // 设置光源
            light.position.set(0, 250, 0);
            scene.add(light); 

            // CUBE
            var cubeGeometry = new THREE.CubeGeometry(260, 35, 185, 1, 1, 1); // 定义一个立方体，就是那本书的模型 

            var cubeMaterialArray = [];
            cubeMaterialArray.push(new THREE.MeshBasicMaterial({
                map : new THREE.ImageUtils.loadTexture('img/side-up.png') // 给每一面上贴图，下同
            }));
            cubeMaterialArray.push(new THREE.MeshBasicMaterial({
                map : new THREE.ImageUtils.loadTexture('img/side-up.png')
            }));
            cubeMaterialArray.push(new THREE.MeshBasicMaterial({
                map : new THREE.ImageUtils.loadTexture('img/up.png')
            }));
            cubeMaterialArray.push(new THREE.MeshBasicMaterial({
                map : new THREE.ImageUtils.loadTexture('img/down.png')
            }));
            cubeMaterialArray.push(new THREE.MeshBasicMaterial({
                map : new THREE.ImageUtils.loadTexture('img/side-right.png')
            }));
            cubeMaterialArray.push(new THREE.MeshBasicMaterial({
                map : new THREE.ImageUtils.loadTexture('img/side-left.png')
            }));
            var cubeMaterials = new THREE.MeshFaceMaterial(cubeMaterialArray); 

            cube = new THREE.Mesh(cubeGeometry, cubeMaterials);
            cube.position.set(0, 0, 0); // 立方体放置的位置
            scene.add(cube); 

        } 

        function animate() {
            requestAnimationFrame(animate);
            render();
            update();
        } 

        function update() {
            // delta = change in time since last call (in seconds)
            var delta = clock.getDelta(); 

            controls.update();
            stats.update();
        } 

        function render() {
            renderer.render(scene, camera);
        }
    </script> 

</body>
</html>