var Floor = gltf.scene.getObjectById(2307);

Floor.material = new THREE.MeshLambertMaterial({

        color: 0x000000,

 });

var Floor = gltf.scene.getObjectByName('地面');

Floor.material = new THREE.MeshLambertMaterial({

       color: 0x000000,

 });

var Floor = gltf.scene.getObjectById(2307);

Floor.material = new THREE.MeshLambertMaterial({

color: 0x000000,

transparent: true,

opacity:0.2,//设置透明度 

visible: true

});