1,各浏覽器對WebGL的支援
書的源碼：https://github.com/josdirksen/learning-threejs
第一次用浏覽器打開代碼可能無法正常顯示，好像要對浏覽器做一些設定額。
建立第一個3D場景包括這幾樣東西：
<!DOCTYPE html>
<html>
<head>
<title>Example 01.06 - Screen size change</title>
<script type="text/javascript" src="../libs/three.js"></script>
<script type="text/javascript" src="../libs/stats.js"></script>//shows the frames per second(fps) for animation
<script type="text/javascript" src="../libs/dat.gui.js"></script>//allows you to very easily create a simple user interface component that can change variables in your code
<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">
var camera;
var scene;
var renderer;
// once everything is loaded, we run our Three.js stuff.
function init() {
var stats = initStats();
// create a scene, that will hold all our elements such as objects, cameras and lights.
scene = new THREE.Scene();
// create a camera, which defines where we're looking at. 第一個參數是錄影機的角度，其他因素不變的情況下角度越大，看到的場景越小，第二個是場景的比例，第三個是near，第四個是far我們能看到的是near和far之間的内容
camera = new THREE.PerspectiveCamera(45, window.innerWidth / window.innerHeight, 0.1, 1000);
// create a render and set the size
renderer = new THREE.WebGLRenderer();
renderer.setClearColor(new THREE.Color(0xEEEEEE, 1.0));
renderer.setSize(window.innerWidth, window.innerHeight);
renderer.shadowMapEnabled = true;//預設是不開啟陰影效果的，如果要顯示陰影在這裡要把它設為true;
// create the ground plane
var planeGeometry = new THREE.PlaneGeometry(60, 20, 1, 1);//建立一個長為60，寬為20的長方形，後面那兩個參數是可選的，分别為widthsegements,heightsegements
var planeMaterial = new THREE.MeshLambertMaterial({color: 0xffffff});//設定材質，并初始化材質顔色
var plane = new THREE.Mesh(planeGeometry, planeMaterial); //把二者合并為一個mesh對象
plane.receiveShadow = true;//接收陰影
// 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.BoxGeometry(4, 4, 4);//建立一個立方體，參數為width,height,depth,後面還有三個可選參數，分别為widthsegments,heightsegments,depthsegments
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);//SphereGeometry(radius, widthSegments, heightSegments, phiStart, phiLength, thetaStart, thetaLength) 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
document.getElementById("WebGL-output").appendChild(renderer.domElement);
// call the render function
var step = 0;
var controls = new function () {
this.rotationSpeed = 0.02;
this.bouncingSpeed = 0.03;
};
var gui = new dat.GUI();
gui.add(controls, 'rotationSpeed', 0, 0.5);
gui.add(controls, 'bouncingSpeed', 0, 0.5);
render();
function render() {
stats.update();
// rotate the cube around its axes
cube.rotation.x += controls.rotationSpeed;
cube.rotation.y += controls.rotationSpeed;
cube.rotation.z += controls.rotationSpeed;
// bounce the sphere up and down
step += controls.bouncingSpeed;
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';
document.getElementById("Stats-output").appendChild(stats.domElement);
return stats;
}
}
function onResize() {
camera.aspect = window.innerWidth / window.innerHeight;
camera.updateProjectionMatrix();
renderer.setSize(window.innerWidth, window.innerHeight);
}
window.onload = init;
// listen to the resize events
window.addEventListener('resize', onResize, false);
</script>
</body>
</html>