第一章 用three.js创建你的第一个3D场景
第一章 用three.js创建你的第一个3D场景
到官网下载three.js的源码和示例。
创建HTML框架界面
第一个示例的代码如下： 01-basic-skeleton.html 位于
Learning Three.js- The JavaScript 3D Library for WebGL\chapter-01<!DOCTYPE html>
<html>
<head>
<title>Example 01.01 - Basic skeleton</title>
<script type="text/javascript"
src="../libs/three.js"></script>
<script type="text/javascript"
src="../libs/jquery-1.9.0.js"></script>
<style>
body{
/* set margin to 0 and overflow to hidden,
to use the complete page */
margin: 0;
overflow: hidden;
}
</style>
</head>
<body>
<!-- Div which will hold the Output -->
<div id="WebGL-output">
</div>
<!-- Javascript code that runs our Three.js examples -->
<script type="text/javascript">
// once everything is loaded, we run our Three.js stuff.
$(function () {
// here we'll put the Three.js stuff
});
</script>
</body>
</html>Three.js 有两个版本：
• Three.min.js:压缩版本，去掉了空格和换行，大小变小了，加载时占用系统资源小。
• Three.js:未压缩版本，易于阅读和调试，但加载时占用系统资源较大。
渲染和展示一个三维物体
我们接下来将会创建我们的第一个场景并添加一系列的物体。其中包括：
• Plane :有两个面的矩形，作为我们场景的地面，将会在场景中部渲染成一个灰色的矩形。
• Cube :正方体，我们将渲染成红色。
• Sphere ：球体，我们将渲染成蓝色。
• Camera ：相机决定了看到了什么。
• Axes ：坐标轴，x,y,z轴。一个很好的调试工具，能够让你知道物体渲染在哪里。
第二个示例的代码如下 02-first-scene.html 位于
Learning Three.js- The JavaScript 3D Library for WebGL\chapter-01<!DOCTYPE html>
<html>
<head>
<title>Example 01.02 - First Scene</title>
<script type="text/javascript" src="../libs/three.js"></script>
<script type="text/javascript" src="../libs/jquery-1.9.0.js"></script>
<style>
body{
/* set margin to 0 and overflow to hidden, to go fullscreen */
margin: 0;
overflow: hidden;
}
</style>
</head>
<body>
<!-- Div which will hold the Output -->
<div id="WebGL-output">
</div>
<!-- Javascript code that runs our Three.js examples -->
<script type="text/javascript">
// once everything is loaded, we run our Three.js stuff.
$(function () {
// create a scene, that will hold all our elements such as objects, cameras and lights.
var scene = new THREE.Scene();
// create a camera, which defines where we're looking at.
var camera = new THREE.PerspectiveCamera(45, window.innerWidth / window.innerHeight, 0.1, 1000);
// create a render and set the size
var renderer = new THREE.WebGLRenderer();
renderer.setClearColorHex(0xEEEEEE);
renderer.setSize(window.innerWidth, window.innerHeight);
var axes = new THREE.AxisHelper( 20 );
scene.add(axes);
// create the ground plane
var planeGeometry = new THREE.PlaneGeometry(60,20);
var planeMaterial = new THREE.MeshBasicMaterial({color: 0xcccccc});
var plane = new THREE.Mesh(planeGeometry,planeMaterial);
// rotate and position the plane
plane.rotation.x=-0.5*Math.PI;
plane.position.x=15
plane.position.y=0
plane.position.z=0
// add the plane to the scene
scene.add(plane);
// create a cube
var cubeGeometry = new THREE.CubeGeometry(4,4,4);
var cubeMaterial = new THREE.MeshBasicMaterial({color: 0xff0000, wireframe: true});
var cube = new THREE.Mesh(cubeGeometry, cubeMaterial);
// position the cube
cube.position.x=-4;
cube.position.y=3;
cube.position.z=0;
// add the cube to the scene
scene.add(cube);
var sphereGeometry = new THREE.SphereGeometry(4,20,20);
var sphereMaterial = new THREE.MeshBasicMaterial({color: 0x7777ff, wireframe: true});
var sphere = new THREE.Mesh(sphereGeometry,sphereMaterialMaterial);
// position the sphere
sphere.position.x=20;
sphere.position.y=4;
sphere.position.z=2;
// add the sphere to the scene
scene.add(sphere);
// position and point the camera to the center of the scene
camera.position.x = -30;
camera.position.y = 40;
camera.position.z = 30;
camera.lookAt(scene.position);
// add the output of the renderer to the html element
$("#WebGL-output").append(renderer.domElement);
// render the scene
renderer.render(scene, camera);
});
</script>
</body>
</html>可知有如下几个步骤：
创建并设置scene、render、camera。
创建对象，指定Geometry和Material，设置position并加入到scene中
把渲染的结果显示在 $('div#WebGL-output')对象中。
开始渲染。
加上材质、灯光和阴影
第三个示例的代码如下： 03-materials-light.html 位于
Learning Three.js- The JavaScript 3D Library for WebGL\chapter-01<!DOCTYPE html>
<html>
<head>
<title>Example 01.03 - Materials and light</title>
<script type="text/javascript" src="../libs/three.js"></script>
<script type="text/javascript" src="../libs/jquery-1.9.0.js"></script>
<script type="text/javascript" src="../libs/stats.js"></script>
<script type="text/javascript" src="../libs/dat.gui.js"></script>
<style>
body{
/* set margin to 0 and overflow to hidden, to go fullscreen */
margin: 0;
overflow: hidden;
}
</style>
</head>
<body>
<!-- Div which will hold the Output -->
<div id="WebGL-output">
</div>
<!-- Javascript code that runs our Three.js examples -->
<script type="text/javascript">
// once everything is loaded, we run our Three.js stuff.
$(function () {
// create a scene, that will hold all our elements such as objects, cameras and lights.
var scene = new THREE.Scene();
// create a camera, which defines where we're looking at.
var camera = new THREE.PerspectiveCamera(45, window.innerWidth / window.innerHeight, 0.1, 1000);
// create a render and set the size
var renderer = new THREE.WebGLRenderer();
renderer.setClearColorHex(0xEEEEEE, 1.0);
renderer.setSize(window.innerWidth, window.innerHeight);
renderer.shadowMapEnabled = true;
// create the ground plane
var planeGeometry = new THREE.PlaneGeometry(60,20);
var planeMaterial = new THREE.MeshLambertMaterial({color: 0xffffff});
var plane = new THREE.Mesh(planeGeometry,planeMaterial);
plane.receiveShadow = true;
// rotate and position the plane
plane.rotation.x=-0.5*Math.PI;
plane.position.x=15
plane.position.y=0
plane.position.z=0
// add the plane to the scene
scene.add(plane);
// create a cube
var cubeGeometry = new THREE.CubeGeometry(4,4,4);
var cubeMaterial = new THREE.MeshLambertMaterial({color: 0xff0000});
var cube = new THREE.Mesh(cubeGeometry, cubeMaterial);
cube.castShadow = true;
// position the cube
cube.position.x=-4;
cube.position.y=3;
cube.position.z=0;
// add the cube to the scene
scene.add(cube);
var sphereGeometry = new THREE.SphereGeometry(4,20,20);
var sphereMaterial = new THREE.MeshLambertMaterial({color: 0x7777ff});
var sphere = new THREE.Mesh(sphereGeometry,sphereMaterial);
// position the sphere
sphere.position.x=20;
sphere.position.y=4;
sphere.position.z=2;
sphere.castShadow=true;
// add the sphere to the scene
scene.add(sphere);
// position and point the camera to the center of the scene
camera.position.x = -30;
camera.position.y = 40;
camera.position.z = 30;
camera.lookAt(scene.position);
// add spotlight for the shadows
var spotLight = new THREE.SpotLight( 0xffffff );
spotLight.position.set( -40, 60, -10 );
spotLight.castShadow = true;
scene.add( spotLight );
// add the output of the renderer to the html element
$("#WebGL-output").append(renderer.domElement);
// call the render function
renderer.render(scene, camera);
});
</script>
</body>
</html>分析示例二和示例一可以发现不同之处。
首先，示例二添加的灯光 ，类型是点光源，并且打开了阴影效果。
// add spotlight for the shadows
var spotLight = new THREE.SpotLight( 0xffffff );
spotLight.position.set( -40, 60, -10 );
spotLight.castShadow = true;
scene.add( spotLight );然后，示例一采用的是BasicMaterial材质（效果为三角网格），而示例二采用的是LambertMaterial
材质（效果为一般的纸质效果）。
用动画拓展你的第一个场景
示例四的源码如下： 04-materials-light-animation.html 位于
Learning Three.js- The JavaScript 3D Library for WebGL\chapter-01<!DOCTYPE html>
<html>
<head>
<title>Example 01.04 - Materials, light and animation</title>
<script type="text/javascript" src="../libs/three.js"></script>
<script type="text/javascript" src="../libs/jquery-1.9.0.js"></script>
<script type="text/javascript" src="../libs/stats.js"></script>
<style>
body{
/* set margin to 0 and overflow to hidden, to go fullscreen */
margin: 0;
overflow: hidden;
}
</style>
</head>
<body>
<div id="Stats-output">
</div>
<!-- Div which will hold the Output -->
<div id="WebGL-output">
</div>
<!-- Javascript code that runs our Three.js examples -->
<script type="text/javascript">
// once everything is loaded, we run our Three.js stuff.
$(function () {
var stats = initStats();
// create a scene, that will hold all our elements such as objects, cameras and lights.
var scene = new THREE.Scene();
// create a camera, which defines where we're looking at.
var camera = new THREE.PerspectiveCamera(45, window.innerWidth / window.innerHeight, 0.1, 1000);
// create a render and set the size
var renderer = new THREE.WebGLRenderer();
renderer.setClearColorHex(0xEEEEEE, 1.0);
renderer.setSize(window.innerWidth, window.innerHeight);
renderer.shadowMapEnabled = true;
// create the ground plane
var planeGeometry = new THREE.PlaneGeometry(60,20,1,1);
var planeMaterial = new THREE.MeshLambertMaterial({color: 0xffffff});
var plane = new THREE.Mesh(planeGeometry,planeMaterial);
plane.receiveShadow = true;
// rotate and position the plane
plane.rotation.x=-0.5*Math.PI;
plane.position.x=15
plane.position.y=0
plane.position.z=0
// add the plane to the scene
scene.add(plane);
// create a cube
var cubeGeometry = new THREE.CubeGeometry(4,4,4);
var cubeMaterial = new THREE.MeshLambertMaterial({color: 0xff0000});
var cube = new THREE.Mesh(cubeGeometry, cubeMaterial);
cube.castShadow = true;
// position the cube
cube.position.x=-4;
cube.position.y=3;
cube.position.z=0;
// add the cube to the scene
scene.add(cube);
var sphereGeometry = new THREE.SphereGeometry(4,20,20);
var sphereMaterial = new THREE.MeshLambertMaterial({color: 0x7777ff});
var sphere = new THREE.Mesh(sphereGeometry,sphereMaterial);
// position the sphere
sphere.position.x=20;
sphere.position.y=0;
sphere.position.z=2;
sphere.castShadow=true;
// add the sphere to the scene
scene.add(sphere);
// position and point the camera to the center of the scene
camera.position.x = -30;
camera.position.y = 40;
camera.position.z = 30;
camera.lookAt(scene.position);
// add subtle ambient lighting
var ambientLight = new THREE.AmbientLight(0x0c0c0c);
scene.add(ambientLight);
// add spotlight for the shadows
var spotLight = new THREE.SpotLight( 0xffffff );
spotLight.position.set( -40, 60, -10 );
spotLight.castShadow = true;
scene.add( spotLight );
// add the output of the renderer to the html element
$("#WebGL-output").append(renderer.domElement);
// call the render function
var step=0;
render();
function render() {
stats.update();
// rotate the cube around its axes
cube.rotation.x += 0.02;
cube.rotation.y += 0.02;
cube.rotation.z += 0.02;
// bounce the sphere up and down
step+=0.04;
sphere.position.x = 20+( 10*(Math.cos(step)));
sphere.position.y = 2 +( 10*Math.abs(Math.sin(step)));
// render using requestAnimationFrame
requestAnimationFrame(render);
renderer.render(scene, camera);
}
function initStats() {
var stats = new Stats();
stats.setMode(0); // 0: fps, 1: ms
// Align top-left
stats.domElement.style.position = 'absolute';
stats.domElement.style.left = '0px';
stats.domElement.style.top = '0px';
$("#Stats-output").append( stats.domElement );
return stats;
}
});
</script>
</body>
</html>分析源码可知与示例三的不同有：
function initStats() {
var stats = new Stats();
stats.setMode(0); // 0: fps, 1: ms
// Align top-left
stats.domElement.style.position = 'absolute';
stats.domElement.style.left = '0px';
stats.domElement.style.top = '0px';
$("#Stats-output").append( stats.domElement );
return stats;
}这里这个函数创建了一个Stats，也就是左上角的显示帧数的方框。方法就是创建一个Stats，并设置
参数，然后将结果显示在$('#Stats-output')中。
然后看这段代码：
var step=0;
render();
function render() {
stats.update();
// rotate the cube around its axes
cube.rotation.x += 0.02;
cube.rotation.y += 0.02;
cube.rotation.z += 0.02;
// bounce the sphere up and down
step+=0.04;
sphere.position.x = 20+( 10*(Math.cos(step)));
sphere.position.y = 2 +( 10*Math.abs(Math.sin(step)));
// render using requestAnimationFrame
requestAnimationFrame(render);
renderer.render(scene, camera);
}这里更改了cube和sphere的角度和位置，然后调用requestAnimationFrame函数，该函数就是调用传入的参数render，然后就进入渲染循环，就产生了动画。
运用 dat.GUI库使得实验更简易
创建一个GUI 接受rotationSpeed和bouncingSpeed，值在0~0.5之间。
var gui = new dat.GUI();
gui.add(controls, 'rotationSpeed',0,0.5);
gui.add(controls, 'bouncingSpeed',0,0.5);创建一个javascript对象用来包含rotationSpeed和bouncingSpeed。
var controls = new function() {
this.rotationSpeed = 0.02;
this.bouncingSpeed = 0.03;
}然后改变的角度和位置可以采用controls的值。