为什么 3d 模型在 Three.js 中可见而不使用任何光源？

Question

我有什么

如下图所示，我使用Three.js库创建了一个WEBGL canvas并使用GLTFLoader.js在场景中加载了一个.gltf模型。

我使用的代码

//Add THREE Renderer
renderer_Main = new THREE.WebGLRenderer({ antialias: true });
renderer_Main.setSize(canvasWidth, canvasHeight); //Set Renderer Size

//Add THREE Scene
scene_Main = new THREE.Scene();

//Add First THREE Camera
camera_Main = new THREE.PerspectiveCamera(45, window.innerWidth / window.innerHeight, 0.01, 10000);
camera_Main.position.set(-2000, 500, 500); //Set camera position

//Add THREE Grid Helper
var size = 1000; //Value of Each Square Size 
var divisions = 60; //Value of Grid Divisions 
gridHelper = new THREE.GridHelper(size, divisions);
gridHelper.material.opacity = 0.045;
gridHelper.material.transparent = false;
scene_Main.add(gridHelper); //Add Grid in the Scene

//Add THREE Orbit Controller for the first camera
//Activate mouse events (L_Click, Scroll, R_Click) for moving around in 3D scene
orbitController_Main = new THREE.OrbitControls(camera_Main, renderer_Main.domElement);
orbitController_Main.maxPolarAngle = Math.PI / 2;  
orbitController_Main.saveState();

//Add Lights
//var directionalLight = new THREE.DirectionalLight( 0xffffff, 0.5 );
//scene_Main.add( directionalLight );

//Add a model (.gltf file)
var loader = new THREE.GLTFLoader();
loader.load( 'models/model_environment/scene.gltf', 
    function ( gltf ) {
        //Add 3d model - file types : .gltf, .bin and (.png materials)
        selectedModel = gltf.scene; 
        selectedModel.scale.set(3,3,3);
        selectedModel.position.y = 45;
        scene_Main.add(selectedModel);
    }, 
    ...
);

问题

问题是加载对象时是可见的。请注意，我没有使用任何类型的灯光（已评论）。此外，当添加灯光时，没有任何变化。我尝试使用 THREE.DirectionalLight and THREE.PointLight，但没有成功。如果您想知道我在此示例中使用的材料是：

1) 立方体：

camera_RT_Holder = new THREE.Mesh(
   new THREE.BoxGeometry(20, 20, 30),
   new THREE.MeshNormalMaterial()
);

2）.gltf 模型：

Link of the model

问题如果您知道发生了什么，请告诉我。

Answer 1

您的 glTF 文件中的 material 使用 KHR_materials_unlit extension. Materials using this extensions are mapped to THREE.MeshBasicMaterial，它是未点亮的 material。这意味着它不会对灯光做出反应，因此即使场景中没有任何光源，它也可见。

为什么 3d 模型在 Three.js 中可见而不使用任何光源？

Why 3d models are visible in Three.js without using any light sources?

javascript

3d

model

light

three.js