three.js初学之简单地月旋转

最近在b站上找了个three.js视频学习了一下，照着模仿了一下地月旋转，模仿的过程中发现加载图片实际是异步进行，不知道是three.js的版本问题还是别的什么原因，我按照视频上的代码实现发现图片加载不上，没办法只能用回调方式，有过相关经历的3d大牛可以指点一下。(看的视频是老XXX的three.js教学，b站直接能搜到)
最终效果：
首先新建一个简单的web项目，目录如下，其中相关图片和three.js在网上下就行：

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css文件：
【three.js初学之简单地月旋转】* {box-sizing: border-box;margin: 0;padding: 0;}canvas {background: url(../img/starbg1.jpg);background-size: cover;}

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html文件：

js文件：

function init() {let earth,moon;let textureLoader = new THREE.TextureLoader();let scene = new THREE.Scene()let camera = new THREE.PerspectiveCamera(45,window.innerWidth/window.innerHeight,0.1,200)camera.position.x = 0;camera.position.y = 2camera.position.z = 20let renderer = new THREE.WebGLRenderer({alpha: 1})renderer.shadowMap.enabled = true;renderer.setSize(window.innerWidth,window.innerHeight)let spotLight = new THREE.SpotLight(0xffffff)spotLight.position.set(20,10,40)spotLight.castShadow = true;scene.add(spotLight)renderer.render(scene,camera)textureLoader.load('./img/earth.jpg',(texture)=> {let earthGeometry = new THREE.SphereGeometry(2,16,16)let earthMaterial = new THREE.MeshPhongMaterial({map: texture})earth = new THREE.Mesh(earthGeometry,earthMaterial)earth.receiveShadow = true;scene.add(earth)})textureLoader.load('./img/moon.jpg',(texture)=> {let moonGeometry = new THREE.SphereGeometry(0.8,16,16)let moonMaterial = new THREE.MeshPhongMaterial({map: texture})moon = new THREE.Mesh(moonGeometry,moonMaterial)moon.position.set(0,0,10)moon.castShadow = true;scene.add(moon)})camera.lookAt(scene.position)document.getElementById('webgl-output').appendChild(renderer.domElement);let earthAxis = new THREE.Vector3(0,1,0);let clock = new THREE.Clock()function animate() {let elapsed = clock.getElapsedTime()if(earth) {earth.rotateOnAxis(earthAxis,0.01)}if(moon) {moon.position.set(Math.cos(elapsed) * 10,0,Math.sin(elapsed)* 10)}renderer.render(scene,camera)requestAnimationFrame(animate)}animate()}window.onload = init