计算环境反光会非常耗费CPU，而且通常会使用光线追踪算法，在three.js中通过环境贴图envMap来伪装反光，并且可以将环境贴图用到指定的对象上。
1、示例
示例
http://ithanmang.com/threeJs/home/201809/20180905/07-envMap-texture.html
效果
2、使用步骤
2.1、创建一个全景的贴图
scene = new THREE.Scene();
scene.background = new THREE.CubeTextureLoader().setPath('../../textures/cube/Park2/')
.load( [
'posx.jpg',
'negx.jpg',
'posy.jpg',
'negy.jpg',
'posz.jpg',
'negz.jpg'
] );2.2、给场景中的对象的材质添加环境贴图
let material = new THREE.MeshPhongMaterial();
material.envMap = scene.background;
let sphereGeometry = new THREE.SphereGeometry(20, 60, 60);
let boxGeometry = new THREE.BoxGeometry(30, 30, 30);
let box = new THREE.Mesh(boxGeometry, material);
let sphere = new THREE.Mesh(sphereGeometry, material);
sphere.translateX(-45);
box.translateX(45);
let loader = new THREE.GLTFLoader();
loader.load('../../models/gltf/DamagedHelmet/glTF/DamagedHelmet.gltf', function (gltf) {
gltf.scene.traverse(function (child) {
if (child.isMesh) {
child.scale.set(25, 25, 25);
child.material.envMap = scene.background;
}
});
scene.add(gltf.scene);
scene.add(box);
scene.add(sphere);
removeLoading();
});示例中添加了三个对象，球体、立方体，加载了一个外部模型。
分别给各自的材质属性的envMap属性设置为scene.background
3、示例代码
<!DOCTYPE html>
<html lang="en">
<head>
<meta charset="UTF-8">
<link rel="icon" href="../../../three.png">
<title>使用环境贴图创建虚假的反光效果</title>
<style>
body {
margin: 0;
overflow: hidden; /* 溢出隐藏 */
}
#loading {
position: fixed;
top: 50%;
left: 50%;
color: #FFFFFF;
font-size: 20px;
margin-top: -30px;
margin-left: -40px;
}
</style>
<script src="../../libs/build/three-r93.js"></script>
<script src="../../libs/examples/js/Detector.js"></script>
<script src="../../libs/examples/js/libs/dat.gui.min.js"></script>
<script src="../../libs/examples/js/libs/stats.min.js"></script>
<script src="../../libs/examples/js/controls/OrbitControls.js"></script>
<script src="../../libs/examples/js/loaders/GLTFLoader.js"></script>
</head>
<body>
<p id="loading">loading......</p>
<script>
let scene, camera, renderer, controls, guiControls;
let stats = initStats();
/* 场景 */
function initScene() {
scene = new THREE.Scene();
scene.background = new THREE.CubeTextureLoader().setPath('../../textures/cube/Park2/')
.load( [
'posx.jpg',
'negx.jpg',
'posy.jpg',
'negy.jpg',
'posz.jpg',
'negz.jpg'
] );
}
/* 相机 */
function initCamera() {
camera = new THREE.PerspectiveCamera(45, window.innerWidth / window.innerHeight, 0.1, 10000);
camera.position.set(0, 10, 100);
camera.lookAt(new THREE.Vector3(0, 0, 0));
}
/* 渲染器 */
function initRender() {
renderer = new THREE.WebGLRenderer({antialias: true});
renderer.setSize(window.innerWidth, window.innerHeight);
document.body.appendChild(renderer.domElement);
}
/* 灯光 */
function initLight() {
scene.add(new THREE.AmbientLight(0xffffff, 0.6));
let spotLight1 = new THREE.SpotLight(0xffffff);
spotLight1.position.set(-400, -400, -400);
let spotLight2 = new THREE.SpotLight(0xffffff);
spotLight2.position.set(400, 400, 400);
scene.add(spotLight1);
scene.add(spotLight2);
}
/* 控制器 */
function initControls() {
/* 地图控件 */
controls = new THREE.OrbitControls(camera, renderer.domElement);
/* 属性参数 */
}
/* 调试插件 */
function initGui() {
guiControls = new function () {
};
let gui = new dat.GUI();
}
/* 场景中的内容 */
function initContent() {
let material = new THREE.MeshPhongMaterial();
material.envMap = scene.background;
let sphereGeometry = new THREE.SphereGeometry(20, 60, 60);
let boxGeometry = new THREE.BoxGeometry(30, 30, 30);
let box = new THREE.Mesh(boxGeometry, material);
let sphere = new THREE.Mesh(sphereGeometry, material);
sphere.translateX(-45);
box.translateX(45);
let loader = new THREE.GLTFLoader();
loader.load('../../models/gltf/DamagedHelmet/glTF/DamagedHelmet.gltf', function (gltf) {
gltf.scene.traverse(function (child) {
if (child.isMesh) {
child.scale.set(25, 25, 25);
child.material.envMap = scene.background;
}
});
scene.add(gltf.scene);
scene.add(box);
scene.add(sphere);
removeLoading();
});
}
/* 移除加载元素 */
function removeLoading() {
document.getElementById('loading').style.display = 'none';
}
/* 性能插件 */
function initStats() {
let stats = new Stats();
document.body.appendChild(stats.domElement);
return stats;
}
/* 窗口变动触发 */
function onWindowResize() {
camera.aspect = window.innerWidth / window.innerHeight;
camera.updateProjectionMatrix();
renderer.setSize(window.innerWidth, window.innerHeight);
}
/* 数据更新 */
function update() {
stats.update();
controls.update();
}
/* 初始化 */
function init() {
if (!Detector.webgl) Detector.addGetWebGLMessage();
initScene();
initCamera();
initRender();
initLight();
initControls();
initContent();
initGui();
/* 监听事件 */
window.addEventListener('resize', onWindowResize, false);
}
/* 循环渲染 */
function animate() {
requestAnimationFrame(animate);
renderer.render(scene, camera);
update();
}
/* 初始加载 */
(function () {
console.log("three init start...");
init();
animate();
console.log("three init end...");
})();
</script>
</body>
</html>