在 Three.js 的 r82 版本中，TextureLoader 是用于加载纹理的对象。
提取（test.js）：
var scene = new THREE.Scene();
var ratio = window.innerWidth / window.innerHeight;
var camera = new THREE.PerspectiveCamera(75, window.innerWidth / window.innerHeight,
0.1, 50);
var renderer = ...
[...]
/**
* Will be called when load completes.
* The argument will be the loaded texture.
*/
var onLoad = function (texture) {
var objGeometry = new THREE.BoxGeometry(20, 20, 20);
var objMaterial = new THREE.MeshPhongMaterial({
map: texture,
shading: THREE.FlatShading
});
var mesh = new THREE.Mesh(objGeometry, objMaterial);
scene.add(mesh);
var render = function () {
requestAnimationFrame(render);
mesh.rotation.x += 0.010;
mesh.rotation.y += 0.010;
renderer.render(scene, camera);
};
render();
}
// Function called when download progresses
var onProgress = function (xhr) {
console.log((xhr.loaded / xhr.total * 100) + '% loaded');
};
// Function called when download errors
var onError = function (xhr) {
console.log('An error happened');
};
var loader = new THREE.TextureLoader();
loader.load('texture.jpg', onLoad, onProgress, onError);
在本例中，纹理在网格的构造函数中加载，多个纹理使用Promises 加载。
提取（Globe.js）：
使用Object3D 创建一个新容器，以便在同一个容器中拥有两个网格：
var Globe = function (radius, segments) {
THREE.Object3D.call(this);
this.name = "Globe";
var that = this;
// instantiate a loader
var loader = new THREE.TextureLoader();
一个名为 textures 的映射，其中每个对象都包含纹理文件的 url 和用于存储 Three.js texture 对象的值的 val。
// earth textures
var textures = {
'map': {
url: 'relief.jpg',
val: undefined
},
'bumpMap': {
url: 'elev_bump_4k.jpg',
val: undefined
},
'specularMap': {
url: 'wateretopo.png',
val: undefined
}
};
promise 数组，对于 map 中名为 textures 的每个对象，在数组 texturePromises 中推送一个新的 Promise，每个 Promise 都会调用 loader.load。如果entry.val 的值是一个有效的THREE.Texture 对象，则解析promise。
var texturePromises = [], path = './';
for (var key in textures) {
texturePromises.push(new Promise((resolve, reject) => {
var entry = textures[key]
var url = path + entry.url
loader.load(url,
texture => {
entry.val = texture;
if (entry.val instanceof THREE.Texture) resolve(entry);
},
xhr => {
console.log(url + ' ' + (xhr.loaded / xhr.total * 100) +
'% loaded');
},
xhr => {
reject(new Error(xhr +
'An error occurred loading while loading: ' +
entry.url));
}
);
}));
}
Promise.all 将 promise 数组 texturePromises 作为参数。这样做会使浏览器等待所有的 Promise 解析，当它们完成时，我们可以加载几何体和材质。
// load the geometry and the textures
Promise.all(texturePromises).then(loadedTextures => {
var geometry = new THREE.SphereGeometry(radius, segments, segments);
var material = new THREE.MeshPhongMaterial({
map: textures.map.val,
bumpMap: textures.bumpMap.val,
bumpScale: 0.005,
specularMap: textures.specularMap.val,
specular: new THREE.Color('grey')
});
var earth = that.earth = new THREE.Mesh(geometry, material);
that.add(earth);
});
对于云球，只需要一个纹理：
// clouds
loader.load('n_amer_clouds.png', map => {
var geometry = new THREE.SphereGeometry(radius + .05, segments, segments);
var material = new THREE.MeshPhongMaterial({
map: map,
transparent: true
});
var clouds = that.clouds = new THREE.Mesh(geometry, material);
that.add(clouds);
});
}
Globe.prototype = Object.create(THREE.Object3D.prototype);
Globe.prototype.constructor = Globe;