.gltf对象在three.js中加载时变黑

Question

这是我的场景，并施加光线。

scene = new THREE.Scene();
defaultCamera = new THREE.PerspectiveCamera( 45, container.offsetWidth / container.offsetHeight, 0.01, 100 );

// defaultCamera.up = new THREE.Vector3( 0, 1, 0 );
scene.add( defaultCamera );
camera = defaultCamera;

var sceneInfo = sceneList[index];
var spot1 = null;
var light = new THREE.DirectionalLight( 0xffffff, 1 );
light.position.set( 10, 10, 10 );
scene.add( light );

此后，我使用.gltf加载gltf2loader模型。我的模型在Android中为黑色。有没有人有办法解决吗？请帮助