[webGL学习技术分享]基于three.js构建WebGL实例

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大多程序员在刚开始理解3D(webGL)的知识时,通常对三维空间可能理解的比较困难,你也可能有困难理解不同的光线是如何工作的，或轴甚至如何位于空间。

今天，我会帮你处理这些问题。three.js所拥有一切必要的手段来为这个 - 帮手。在今天的例子中，我已经准备好为你工作的所有现有佣工示范：ArrowHelper，AxisHelper，BoundingBoxHelper，CameraHelper，DirectionalLightHelper，GridHelper，HemisphereLightHelper，PointLightHelper，SpotLightHelper。所有这些将有助于你理解的WebGL的内部工作原理。

html

这部分没有变,跟之前的一样.

<!DOCTYPE html><html lang="en" >
    <head>
        <meta charset="utf-8" />
        <meta name="author" content="Script Tutorials" />
        <title>WebGL With Three.js - Lesson 2 | Script Tutorials</title>
        <meta name="viewport" content="width=device-width, initial-scale=1.0, maximum-scale=1.0, user-scalable=no">
        <link href="css/main.css" rel="stylesheet" type="text/css" />
    </head>
    <body>
        <script src="js/three.min.js"></script>
        <script src="js/THREEx.WindowResize.js"></script>
        <script src="js/OrbitControls.js"></script>
        <script src="js/stats.min.js"></script>
        <script src="js/script.js"></script>

        <div style="position: absolute; top: 10px; left: 20px; text-align: center;"></div>

        <!-- Only used for Script Tutorial's Demo site. Please ignore and remove. -->
        <script src="http://code.jquery.com/jquery-1.11.0.min.js"></script> 
        <script src="http://www.script-tutorials.com/assets/ads.js" async></script>
    </body></html>

    javascript代码

    首先，让我们来创建一些简单的场景，包括以下内容：摄像头，光线直射，地面和两个领域：

    var dLight, bboxHelper, dlightHelper;// load texturevar texture = THREE.ImageUtils.loadTexture('texture.png');
texture.repeat.set(10, 10);
texture.wrapS = texture.wrapT = THREE.RepeatWrapping;
texture.anisotropy = 16;
texture.needsUpdate = true;var textureBump = THREE.ImageUtils.loadTexture('bump.png');
textureBump.repeat.set(10, 10);
textureBump.wrapS = textureBump.wrapT = THREE.RepeatWrapping;
textureBump.anisotropy = 16;
textureBump.needsUpdate = true;var lesson3 = {
    scene: null,
    camera: null,
    renderer: null,
    container: null,
    controls: null,
    clock: null,
    stats: null,

    init: function() { // Initialization// create main scene
    this.scene = new THREE.Scene();        var SCREEN_WIDTH = window.innerWidth,
        SCREEN_HEIGHT = window.innerHeight;        
    // prepare camera
    var VIEW_ANGLE = 45, ASPECT = SCREEN_WIDTH / SCREEN_HEIGHT, NEAR = 1, FAR = 10000;        this.camera = new THREE.PerspectiveCamera( VIEW_ANGLE, ASPECT, NEAR, FAR);        this.scene.add(this.camera);        this.camera.position.set(-1600, 600, 1200);        this.camera.lookAt(new THREE.Vector3(0,0,0));        
    // prepare renderer
    this.renderer = new THREE.WebGLRenderer({antialias:true, alpha: false});        this.renderer.setSize(SCREEN_WIDTH, SCREEN_HEIGHT);     this.renderer.setClearColor(0xffffff);        this.renderer.shadowMapEnabled = true;        this.renderer.shadowMapSoft = true;        
    // prepare container
    this.container = document.createElement('div');
    document.body.appendChild(this.container);        this.container.appendChild(this.renderer.domElement);   
    // events
    THREEx.WindowResize(this.renderer, this.camera);        
    // prepare controls (OrbitControls)
    this.controls = new THREE.OrbitControls(this.camera, this.renderer.domElement);        this.controls.target = new THREE.Vector3(0, 0, 0);      
    // prepare clock
    this.clock = new THREE.Clock();        
    // prepare stats
    this.stats = new Stats();        this.stats.domElement.style.position = 'absolute';      this.stats.domElement.style.bottom = '0px';        this.stats.domElement.style.zIndex = 10;        this.container.appendChild( this.stats.domElement );    
    // add directional light
    dLight = new THREE.DirectionalLight(0xffffff);
dLight.position.set(0, 400, 0);
    dLight.castShadow = true;        
    // dLight.shadowCameraVisible = true;
    dLight.shadowMapWidth = dLight.shadowMapHeight = 1000;  this.scene.add(dLight);        
    // add simple ground
    var groundGeometry = new THREE.PlaneGeometry(1200, 1200, 1, 1);
ground = new THREE.Mesh(groundGeometry, new THREE.MeshLambertMaterial({
     color: 0x9669FE}));
ground.position.y = -20;
ground.rotation.x = - Math.PI / 2;
    ground.receiveShadow = true;        this.scene.add(ground);        
    // create a new group (Object3D)
    var group = new THREE.Object3D();        
    // add two spheres
    var sphere  = this.drawSphere(-100, 150, new THREE.MeshPhongMaterial({ map: texture, bumpMap: textureBump, color: 0x00ff00, specular: 0xff2200, emissive: 0x004000 })); var sphere2 = this.drawSphere( 100, 150, new THREE.MeshPhongMaterial({ map: texture, bumpMap: textureBump, color: 0x00ff00, specular: 0xff2200, shininess: 3 }));       
    // and add them into the group
    group.add(sphere);
    group.add(sphere2);        this.scene.add(group);        
    // add helpers:
    // 1. ArrowHelper
    var directionV3 = new THREE.Vector3(1, 0, 1);        var originV3 = new THREE.Vector3(0, 200, 0);        var arrowHelper = new THREE.ArrowHelper(directionV3, originV3, 100, 0xff0000, 20, 10); // 100 is length, 20 and 10 are head length and width
    this.scene.add(arrowHelper);        
    // 2. AxisHelper
    var axisHelper = new THREE.AxisHelper(800); // 500 is size
    this.scene.add(axisHelper);        
    // 3. BoundingBoxHelper
    bboxHelper = new THREE.BoundingBoxHelper(group, 0x999999);        this.scene.add(bboxHelper);        
    // 4. CameraHelper
    var cameraParObj = new THREE.Object3D();
cameraParObj.position.y = 200;
    cameraParObj.position.z = 700;        this.scene.add(cameraParObj);
    perspectiveCamera = new THREE.PerspectiveCamera(90, window.innerWidth / window.innerHeight, 0.01, 1500);
    cameraParObj.add(perspectiveCamera);        var cameraHelper = new THREE.CameraHelper(perspectiveCamera);        this.scene.add(cameraHelper);        
    // 5. DirectionalLightHelper
    dlightHelper = new THREE.DirectionalLightHelper(dLight, 50); // 50 is helper sizethis.scene.add(dlightHelper);
},
drawSphere: function(x, z, material) {var sphere = new THREE.Mesh(new THREE.SphereGeometry(70, 70, 20), material);
sphere.rotation.x = sphere.rotation.z = Math.PI * Math.random();
sphere.position.x = x;
sphere.position.y = 100;
sphere.position.z = z;
sphere.castShadow = sphere.receiveShadow = true;        return sphere;
    }
    };
    // Animate the scenefunction animate() {
        requestAnimationFrame(animate);
    render();
    update();
    }
    // Update controls and statsfunction update() {
        bboxHelper.update();
    dlightHelper.update();

    lesson3.controls.update(lesson3.clock.getDelta());
        lesson3.stats.update();    
    // smoothly move the dLight
        var timer = Date.now() * 0.000025;
    dLight.position.x = Math.sin(timer * 5) * 300;
    dLight.position.z = Math.cos(timer * 5) * 300;
    }
    // Render the scenefunction render() {
        if (lesson3.renderer) {
        lesson3.renderer.render(lesson3.scene, lesson3.camera);
    }
    }
    // Initialize lesson on page loadfunction initializeLesson() {
        lesson3.init();
    animate();
    }if (window.addEventListener)
        window.addEventListener('load', initializeLesson, false);else if (window.attachEvent)
        window.attachEvent('onload', initializeLesson);else window.onload = initializeLesson;

      请注意两个球体加入到该组（这是普通的对象的3D对象）。现在，我们可以开始下面的功能实现介绍。

      ArrowHelper

      它利用一个轴对象以可视化的3轴以简单的方式。X轴是红色的。Y轴是绿色的。Z轴是蓝色的。这有助于理解在空间的所有三个轴的方向。要添加这个帮手，使用下面的代码：

      //  AxisHelpervar axisHelper = new THREE.AxisHelper(800);this.scene.add(axisHelper);

        BoundingBoxHelper

        它绘制线条对象的任何对象（Object3D）的外接矩形框，显示此对象的世界轴对齐边框。记住我们结合在单组对象这两个领域？要添加这个帮手，使用下面的代码：

        //3. BoundingBoxHelperbboxHelper = new THREE.BoundingBoxHelper(group, 0x999999);this.scene.add(bboxHelper);

          CameraHelper

          它吸引的特定对象3D对象（它看起来像金字塔）与线几何，这有助于可视化什么指定摄像机包含在它的视锥。要添加这个帮手，使用下面的代码：

          // 4. CameraHelper
          var cameraParObj = new THREE.Object3D();cameraParObj.position.y = 200;cameraParObj.position.z = 700;this.scene.add(cameraParObj);perspectiveCamera = new THREE.PerspectiveCamera(90, window.innerWidth / window.innerHeight, 0.01, 1500);cameraParObj.add(perspectiveCamera);var cameraHelper = new THREE.CameraHelper(perspectiveCamera);this.scene.add(cameraHelper);

            DirectionalLightHelper

            它绘制一个线对象以显示定向的光的方向。我们将逐步把我们的光源的给你看显然这帮手。要添加这个帮手，使用下面的代码：

            // 5. DirectionalLightHelperdlightHelper = new THREE.DirectionalLightHelper(dLight, 50); // 50 is helper sizthis.scene.add(dlightHelper);

              GridHelper

              要查看佣工的其余部分，我们创建了第二个演示。其次是GridHelper，这个辅助绘制线条的二维网格。要添加这个帮手，使用下面的代码：

              var gridHelper = new THREE.GridHelper(500, 40); // 500 is grid size, 20 is grid stepgridHelper.position = new THREE.Vector3(0, 0, 0);gridHelper.rotation = new THREE.Euler(0, 0, 0);this.scene.add(gridHelper);var gridHelper2 = gridHelper.clone();gridHelper2.rotation = new THREE.Euler(Math.PI / 2, 0, 0);this.scene.add(gridHelper2);var gridHelper3 = gridHelper.clone();gridHelper3.rotation = new THREE.Euler(Math.PI / 2, 0, Math.PI / 2);this.scene.add(gridHelper3);

                HemisphereLightHelper

                其余3个助手是灯，HemisphereLightHelper是HemisphereLight对象。我们不得不关闭我们的定向光，使半球光。要添加这个帮手，使用下面的代码：

                // add hemisphere light
                var hemiLight = new THREE.HemisphereLight(0x0000ff, 0x00ff00, 0.4);hemiLight.color.setHSL(0.6, 1, 0.6);hemiLight.groundColor.setHSL(0.095, 1, 0.75);hemiLight.position.set(-200, 400, -200);this.scene.add(hemiLight);var hlightHelper = new THREE.HemisphereLightHelper(hemiLight, 50, 300); // 50 is sphere size, 300 is arrow lengththis.scene.add(hlightHelper);

                  PointLightHelper

                  类似以前的点光源助手是点光源的对象。要添加这个帮手，使用下面的代码：

                  // add point lightvar pointLight = new THREE.PointLight(0xffff00, 1.0);
                  pointLight.position.set(300,300,300);this.scene.add(pointLight);var pointLightHelper = new THREE.PointLightHelper(pointLight, 50); // 50 is sphere sizethis.scene.add(pointLightHelper);

                    SpotLightHelper

                    最后，我们添加了聚光灯下：聚光灯Helper是聚光灯的对象。要添加这个帮手，使用下面的代码：

                    // add spot light
                    var spotLight = new THREE.SpotLight(0xffffff);spotLight.position.set(-300,400,300);spotLight.castShadow = true;spotLight.shadowCameraFov = 60;this.scene.add(spotLight);var spotLightHelper = new THREE.SpotLightHelper(spotLight, 50); // 50 is sphere sizethis.scene.add(spotLightHelper);

                      结束

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