TextLoader没有触发onProgress或onError（three.js 75）

Question

我正在尝试制作一个预加载器，在加载最终可视化之前向查看器显示有用的信息。为此，我试图使用纹理加载器函数中的Three.js。下面是我的版本，下面是文档中的示例...不确定为什么这不起作用。

// add the earth
function addEarth(){
    loadText.textContent = "Creating Earth";

    var planetTexture = loader.load( "earthmap4k_optimized.jpg", function(){
        var planetBump = loader.load( "earthbump4k_optimized.jpg" , function(){
            var planetSpecular = loader.load( "earthspec4k_optimized.jpg", function(){

                var earthTexture =  new THREE.MeshPhongMaterial( {
                    map: planetTexture,
                    bumpMap: planetBump,
                    bumpScale: 0.5,
                    specularMap: planetSpecular
                }),
                earth = new THREE.Mesh(spGeo, earthTexture);
                worldObj.add(earth);
                scene.add(worldObj);
                earthLoaded = true;

            }, function(xhr){loadText.textContent = "Earth Specular Map "+ (xhr.loaded / xhr.total * 100) + "%"},
            function(xhr){loadText.textContent = "Error Loading Earth Specular Map";});

        }, function(xhr){loadText.textContent = "Earth Bump Map "+ (xhr.loaded / xhr.total * 100) + "%"},
        function(xhr){loadText.textContent = "Error Loading Earth Bump Map";});
    }, 
    function(xhr){loadText.textContent = "Earth Texture Map "+ (xhr.loaded / xhr.total * 100) + "%"},
    function(xhr){loadText.textContent = "Error Loading Earth Texture Map";});

}

这是文档中的示例

loader.load(
    // resource URL
    'textures/land_ocean_ice_cloud_2048.jpg',
    // Function when resource is loaded
    function ( texture ) {
        // do something with the texture
        var material = new THREE.MeshBasicMaterial( {
            map: texture
         } );
    },
    // Function called when download progresses
    function ( xhr ) {
        console.log( (xhr.loaded / xhr.total * 100) + '% loaded' );
    },
    // Function called when download errors
    function ( xhr ) {
        console.log( 'An error happened' );
    }
);