[webGL学习]基于three.js构建WebGL实例第一讲

我们主要做些的基本功能：创建一个场景，相机，渲染器，控制器（OrbitControls）。我们也将创建简单的定向光，加上一些对象（不同的几何形状）的阴影。为了使事情更快，我们决定采取一个最流行的WebGL框架——three.js。为什么使用three.js？ 事实上，它是开源的JavaScript框架，它也是增长最迅速的和讨论很热烈的引擎 。在这里，已经准备了很多会用到的东西，从基本的点和向量，到做准备工作的场景、着色器，甚至立体效果。

##HTML结构

##场景渲染

var lesson1 = {
    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(-1000, 1000, 0);
        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
        var dLight = new THREE.DirectionalLight(0xffffff);
        dLight.position.set(1, 1000, 1);
        dLight.castShadow = true;
        dLight.shadowCameraVisible = true;
        dLight.shadowDarkness = 0.2;
        dLight.shadowMapWidth = dLight.shadowMapHeight = 1000;
        this.scene.add(dLight);

        // add particle of light
        particleLight = new THREE.Mesh( new THREE.SphereGeometry(10, 10, 10), new THREE.MeshBasicMaterial({ color: 0x44ff44 }));
        particleLight.position = dLight.position;
        this.scene.add(particleLight);

        // add simple ground
        var groundGeometry = new THREE.PlaneGeometry(1000, 1000, 1, 1);
        ground = new THREE.Mesh(groundGeometry, new THREE.MeshLambertMaterial({
            color: this.getRandColor()
        }));
        ground.position.y = 0;
        ground.rotation.x = - Math.PI / 2;
        ground.receiveShadow = true;
        this.scene.add(ground);

        // add circle shape
        var circle = new THREE.Mesh(new THREE.CircleGeometry(70, 50), new THREE.MeshLambertMaterial({ color: this.getRandColor() }));
        circle.rotation.x = - Math.PI / 2;
        circle.rotation.y = - Math.PI / 3;
        circle.rotation.z = Math.PI / 3;
        circle.position.x = -300;
        circle.position.y = 150;
        circle.position.z = -300;
        circle.castShadow = circle.receiveShadow = true;
        this.scene.add(circle);

        // add cube shape
        var cube = new THREE.Mesh(new THREE.CubeGeometry(100, 100, 100), new THREE.MeshLambertMaterial({ color: this.getRandColor() }));
        cube.rotation.x = cube.rotation.z = Math.PI * 0.1;
        cube.position.x = -300;
        cube.position.y = 150;
        cube.position.z = -100;
        cube.castShadow = cube.receiveShadow = true;
        this.scene.add(cube);

        // add cylinder shape
        var cube = new THREE.Mesh(new THREE.CylinderGeometry(60, 80, 90, 32), new THREE.MeshLambertMaterial({ color: this.getRandColor() }));
        cube.rotation.x = cube.rotation.z = Math.PI * 0.1;
        cube.position.x = -300;
        cube.position.y = 150;
        cube.position.z = 100;
        cube.castShadow = cube.receiveShadow = true;
        this.scene.add(cube);

        // add extrude geometry shape
        var extrudeSettings = {
            amount: 10,
            steps: 10,
            bevelSegments: 10,
            bevelSize: 10,
            bevelThickness: 10
        };
        var triangleShape = new THREE.Shape();
        triangleShape.moveTo(  0, -50 );
        triangleShape.lineTo(  -50, 50 );
        triangleShape.lineTo( 50, 50 );
        triangleShape.lineTo(  0, -50 );

        var extrude = new THREE.Mesh(new THREE.ExtrudeGeometry(triangleShape, extrudeSettings), new THREE.MeshLambertMaterial({ color: this.getRandColor() }));
        extrude.rotation.y = Math.PI / 2;
        extrude.position.x = -300;
        extrude.position.y = 150;
        extrude.position.z = 300;
        extrude.castShadow = extrude.receiveShadow = true;
        this.scene.add(extrude);

        // add icosahedron shape
        var icosahedron = new THREE.Mesh(new THREE.IcosahedronGeometry(70), new THREE.MeshLambertMaterial({ color: this.getRandColor() }));
        icosahedron.position.x = -100;
        icosahedron.position.y = 150;
        icosahedron.position.z = -300;
        icosahedron.castShadow = icosahedron.receiveShadow = true;
        this.scene.add(icosahedron);

        // add octahedron shape
        var octahedron = new THREE.Mesh(new THREE.OctahedronGeometry(70), new THREE.MeshLambertMaterial({ color: this.getRandColor() }));
        octahedron.position.x = -100;
        octahedron.position.y = 150;
        octahedron.position.z = -100;
        octahedron.castShadow = octahedron.receiveShadow = true;
        this.scene.add(octahedron);

        // add ring shape
        var ring = new THREE.Mesh(new THREE.RingGeometry(30, 70, 32), new THREE.MeshLambertMaterial({ color: this.getRandColor() }));
        ring.rotation.y = -Math.PI / 2;
        ring.position.x = -100;
        ring.position.y = 150;
        ring.position.z = 100;
        ring.castShadow = ring.receiveShadow = true;
        this.scene.add(ring);

        // add shape geometry shape
        var shapeG = new THREE.Mesh(new THREE.ShapeGeometry(triangleShape), new THREE.MeshLambertMaterial({ color: this.getRandColor() }));
        shapeG.rotation.y = -Math.PI / 2;
        shapeG.position.x = -100;
        shapeG.position.y = 150;
        shapeG.position.z = 300;
        shapeG.castShadow = shapeG.receiveShadow = true;
        this.scene.add(shapeG);

        // add sphere shape
        var sphere = new THREE.Mesh(new THREE.SphereGeometry(70, 32, 32), new THREE.MeshLambertMaterial({ color: this.getRandColor() }));
        sphere.rotation.y = -Math.PI / 2;
        sphere.position.x = 100;
        sphere.position.y = 150;
        sphere.position.z = -300;
        sphere.castShadow = sphere.receiveShadow = true;
        this.scene.add(sphere);

        // add tetrahedron shape
        var tetrahedron = new THREE.Mesh(new THREE.TetrahedronGeometry(70), new THREE.MeshLambertMaterial({ color: this.getRandColor() }));
        tetrahedron.position.x = 100;
        tetrahedron.position.y = 150;
        tetrahedron.position.z = -100;
        tetrahedron.castShadow = tetrahedron.receiveShadow = true;
        this.scene.add(tetrahedron);

        // add torus shape
        var torus = new THREE.Mesh(new THREE.TorusGeometry(70, 20, 16, 100), new THREE.MeshLambertMaterial({ color: this.getRandColor() }));
        torus.rotation.y = -Math.PI / 2;
        torus.position.x = 100;
        torus.position.y = 150;
        torus.position.z = 100;
        torus.castShadow = torus.receiveShadow = true;
        this.scene.add(torus);

        // add torus knot shape
        var torusK = new THREE.Mesh(new THREE.TorusKnotGeometry(70, 20, 16, 100), new THREE.MeshLambertMaterial({ color: this.getRandColor() }));
        torusK.rotation.y = -Math.PI / 2;
        torusK.position.x = 100;
        torusK.position.y = 150;
        torusK.position.z = 300;
        torusK.castShadow = torusK.receiveShadow = true;
        this.scene.add(torusK);

        // add tube shape
        var points = [];
        for (var i = 0; i < 10; i++) {
            var randomX = -100 + Math.round(Math.random() * 200);
            var randomY = -100 + Math.round(Math.random() * 200);
            var randomZ = -100 + Math.round(Math.random() * 200);

            points.push(new THREE.Vector3(randomX, randomY, randomZ));
        }
        var tube = new THREE.Mesh(new THREE.TubeGeometry(new THREE.SplineCurve3(points), 64, 20), new THREE.MeshLambertMaterial({ color: this.getRandColor() }));
        tube.rotation.y = -Math.PI / 2;
        tube.position.x = 0;
        tube.position.y = 500;
        tube.position.z = 0;
        tube.castShadow = tube.receiveShadow = true;
        this.scene.add(tube);
    },
    getRandColor: function() {
        return colors[Math.floor(Math.random() * colors.length)];
    }
};

// Animate the scene
function animate() {
    requestAnimationFrame(animate);
    render();
    update();
}

// Update controls and stats
function update() {
    lesson1.controls.update(lesson1.clock.getDelta());
    lesson1.stats.update();

    // smoothly move the particleLight
    var timer = Date.now() * 0.000025;
    particleLight.position.x = Math.sin(timer * 5) * 300;
    particleLight.position.z = Math.cos(timer * 5) * 300;
}

// Render the scene
function render() {
    if (lesson1.renderer) {
        lesson1.renderer.render(lesson1.scene, lesson1.camera);
    }
}

// Initialize lesson on page load
function initializeLesson() {
    lesson1.init();
    animate();
}

这是用 three.js 建应用的常用结构。几乎所有的东西都将在init方法里创建。

##场景创建、相机和渲染

// 创建主要场景
this.scene = new THREE.Scene();

var SCREEN_WIDTH = window.innerWidth,
    SCREEN_HEIGHT = window.innerHeight;

// 准备相机
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(-1000, 1000, 0);
this.camera.lookAt(new THREE.Vector3(0,0,0));

// 准备渲染
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;

// 准备容器
this.container = document.createElement('div');
document.body.appendChild(this.container);
this.container.appendChild(this.renderer.domElement);

// 事件
// events
        THREEx.WindowResize(this.renderer, this.camera);

       

我们将相机把相机放在45度角，设为全屏幕大小，WebGLRenderer设为白色，再把我们的场景添加到HTML文档中，而且在浏览器窗口大小变化时，用THREEx.WindowResize 来控制渲染和相机的变化。

##OrbitControls 和 Stats

为了能够在某种程度上控制相机的 —— three.js 给我们提供了现成的控件。其中之一是 OrbitControls，它能在场景中绕其轴线旋转。一个小插件stats.min.js将有助于我们看到场景的统计（FPS）。

        // 准备控制器
        this.controls = new THREE.OrbitControls(this.camera, this.renderer.domElement);
        this.controls.target = new THREE.Vector3(0, 0, 0);

        // 开始计数
        this.clock = new THREE.Clock();

        //开始统计
        this.stats = new Stats();
        this.stats.domElement.style.position = 'absolute';
        this.stats.domElement.style.bottom = '0px';
        this.stats.domElement.style.zIndex = 10;
        this.container.a

##光和场地的创作

光是一个场景中的重要元素，在我们的第一个教程，我们将创建最简单的定向光线，因为我们要添加基本的阴影：

// 添加定向光线
var dLight = new THREE.DirectionalLight(0xffffff);
dLight.position.set(1, 1000, 1);
dLight.castShadow = true;
dLight.shadowCameraVisible = true;
dLight.shadowDarkness = 0.2;
dLight.shadowMapWidth = dLight.shadowMapHeight = 1000;
this.scene.add(dLight);

// 添加粒子光线
particleLight = new THREE.Mesh( new THREE.SphereGeometry(10, 10, 10), new THREE.MeshBasicMaterial({ color: 0x44ff44 }));
particleLight.position = dLight.position;
this.scene.add(particleLight);

// 添加简单的场地
var groundGeometry = new THREE.PlaneGeometry(1000, 1000, 1, 1);
ground = new THREE.Mesh(groundGeometry, new THREE.MeshLambertMaterial({
    color: this.getRandColor()
}));
ground.position.y = 0;
ground.rotation.x = - Math.PI / 2;
ground.receiveShadow = true;
this.scene.add(ground);

当我们创建灯光时，用了两个参数 castShadow 和 shadowCameraVisible。这将使我们能够直观地看到光在哪里，理解构造的过程（和边界）的阴影。
你也可能会注意到，在添加光后，我们增加了一个球形物体——为你准备的，以便直观地知道我们的定向光源在什么位置。我们用一个平面作为地面去接收阴影——我们设置的receiveShadow参数为true。

##颜色设置

var colors = [
    0xFF62B0,
    0x9A03FE,
    0x62D0FF,
    0x48FB0D,
    0xDFA800,
    0xC27E3A,
    0x990099,
    0x9669FE,
    0x23819C,
    0x01F33E,
    0xB6BA18,
    0xFF800D,
    0xB96F6F,
    0x4A9586
];

getRandColor: function() {
    return colors[Math.floor(Math.random() * colors.length)];
}

我们将在场景中添加额外的对象。我用一个方法来生成不同颜色的部件。这个方法将从颜色列表中随机返回一个预定义的颜色。

##建模型

 // add simple ground
        var groundGeometry = new THREE.PlaneGeometry(1000, 1000, 1, 1);
        ground = new THREE.Mesh(groundGeometry, new THREE.MeshLambertMaterial({
            color: this.getRandColor()
        }));
        ground.position.y = 0;
        ground.rotation.x = - Math.PI / 2;
        ground.receiveShadow = true;
        this.scene.add(ground);

        // add circle shape
        var circle = new THREE.Mesh(new THREE.CircleGeometry(70, 50), new THREE.MeshLambertMaterial({ color: this.getRandColor() }));
        circle.rotation.x = - Math.PI / 2;
        circle.rotation.y = - Math.PI / 3;
        circle.rotation.z = Math.PI / 3;
        circle.position.x = -300;
        circle.position.y = 150;
        circle.position.z = -300;
        circle.castShadow = circle.receiveShadow = true;
        this.scene.add(circle);

        // add cube shape
        var cube = new THREE.Mesh(new THREE.CubeGeometry(100, 100, 100), new THREE.MeshLambertMaterial({ color: this.getRandColor() }));
        cube.rotation.x = cube.rotation.z = Math.PI * 0.1;
        cube.position.x = -300;
        cube.position.y = 150;
        cube.position.z = -100;
        cube.castShadow = cube.receiveShadow = true;
        this.scene.add(cube);

        // add cylinder shape
        var cube = new THREE.Mesh(new THREE.CylinderGeometry(60, 80, 90, 32), new THREE.MeshLambertMaterial({ color: this.getRandColor() }));
        cube.rotation.x = cube.rotation.z = Math.PI * 0.1;
        cube.position.x = -300;
        cube.position.y = 150;
        cube.position.z = 100;
        cube.castShadow = cube.receiveShadow = true;
        this.scene.add(cube);

        // add extrude geometry shape
        var extrudeSettings = {
            amount: 10,
            steps: 10,
            bevelSegments: 10,
            bevelSize: 10,
            bevelThickness: 10
        };
        var triangleShape = new THREE.Shape();
        triangleShape.moveTo(  0, -50 );
        triangleShape.lineTo(  -50, 50 );
        triangleShape.lineTo( 50, 50 );
        triangleShape.lineTo(  0, -50 );

        var extrude = new THREE.Mesh(new THREE.ExtrudeGeometry(triangleShape, extrudeSettings), new THREE.MeshLambertMaterial({ color: this.getRandColor() }));
        extrude.rotation.y = Math.PI / 2;
        extrude.position.x = -300;
        extrude.position.y = 150;
        extrude.position.z = 300;
        extrude.castShadow = extrude.receiveShadow = true;
        this.scene.add(extrude);

        // add icosahedron shape
        var icosahedron = new THREE.Mesh(new THREE.IcosahedronGeometry(70), new THREE.MeshLambertMaterial({ color: this.getRandColor() }));
        icosahedron.position.x = -100;
        icosahedron.position.y = 150;
        icosahedron.position.z = -300;
        icosahedron.castShadow = icosahedron.receiveShadow = true;
        this.scene.add(icosahedron);

        // add octahedron shape
        var octahedron = new THREE.Mesh(new THREE.OctahedronGeometry(70), new THREE.MeshLambertMaterial({ color: this.getRandColor() }));
        octahedron.position.x = -100;
        octahedron.position.y = 150;
        octahedron.position.z = -100;
        octahedron.castShadow = octahedron.receiveShadow = true;
        this.scene.add(octahedron);

        // add ring shape
        var ring = new THREE.Mesh(new THREE.RingGeometry(30, 70, 32), new THREE.MeshLambertMaterial({ color: this.getRandColor() }));
        ring.rotation.y = -Math.PI / 2;
        ring.position.x = -100;
        ring.position.y = 150;
        ring.position.z = 100;
        ring.castShadow = ring.receiveShadow = true;
        this.scene.add(ring);

        // add shape geometry shape
        var shapeG = new THREE.Mesh(new THREE.ShapeGeometry(triangleShape), new THREE.MeshLambertMaterial({ color: this.getRandColor() }));
        shapeG.rotation.y = -Math.PI / 2;
        shapeG.position.x = -100;
        shapeG.position.y = 150;
        shapeG.position.z = 300;
        shapeG.castShadow = shapeG.receiveShadow = true;
        this.scene.add(shapeG);

        // add sphere shape
        var sphere = new THREE.Mesh(new THREE.SphereGeometry(70, 32, 32), new THREE.MeshLambertMaterial({ color: this.getRandColor() }));
        sphere.rotation.y = -Math.PI / 2;
        sphere.position.x = 100;
        sphere.position.y = 150;
        sphere.position.z = -300;
        sphere.castShadow = sphere.receiveShadow = true;
        this.scene.add(sphere);

        // add tetrahedron shape
        var tetrahedron = new THREE.Mesh(new THREE.TetrahedronGeometry(70), new THREE.MeshLambertMaterial({ color: this.getRandColor() }));
        tetrahedron.position.x = 100;
        tetrahedron.position.y = 150;
        tetrahedron.position.z = -100;
        tetrahedron.castShadow = tetrahedron.receiveShadow = true;
        this.scene.add(tetrahedron);

        // add torus shape
        var torus = new THREE.Mesh(new THREE.TorusGeometry(70, 20, 16, 100), new THREE.MeshLambertMaterial({ color: this.getRandColor() }));
        torus.rotation.y = -Math.PI / 2;
        torus.position.x = 100;
        torus.position.y = 150;
        torus.position.z = 100;
        torus.castShadow = torus.receiveShadow = true;
        this.scene.add(torus);

        // add torus knot shape
        var torusK = new THREE.Mesh(new THREE.TorusKnotGeometry(70, 20, 16, 100), new THREE.MeshLambertMaterial({ color: this.getRandColor() }));
        torusK.rotation.y = -Math.PI / 2;
        torusK.position.x = 100;
        torusK.position.y = 150;
        torusK.position.z = 300;
        torusK.castShadow = torusK.receiveShadow = true;
        this.scene.add(torusK);

        // add tube shape
        var points = [];
        for (var i = 0; i < 10; i++) {
            var randomX = -100 + Math.round(Math.random() * 200);
            var randomY = -100 + Math.round(Math.random() * 200);
            var randomZ = -100 + Math.round(Math.random() * 200);

            points.push(new THREE.Vector3(randomX, randomY, randomZ));
        }
        var tube = new THREE.Mesh(new THREE.TubeGeometry(new THREE.SplineCurve3(points), 64, 20), new THREE.MeshLambertMaterial({ color: this.getRandColor() }));
        tube.rotation.y = -Math.PI / 2;
        tube.position.x = 0;
        tube.position.y = 500;
        tube.position.z = 0;
        tube.castShadow = tube.receiveShadow = true;
        this.scene.add(tube);
    },
    getRandColor: function() {
        return colors[Math.floor(Math.random() * colors.length)];
    }
};

##设置运动样式

为了顺利地将光，我们只需要在update方法里添加以下代码：

// Update controls and stats
function update() {
    lesson1.controls.update(lesson1.clock.getDelta());
    lesson1.stats.update();

    // smoothly move the particleLight
    var timer = Date.now() * 0.000025;
    particleLight.position.x = Math.sin(timer * 5) * 300;
    particleLight.position.z = Math.cos(timer * 5) * 300;
}

##结束
源码下载请关注我的微信公众号