Loading models

• Attach DRACOLoader and KTX2Loader to GLTFLoader before calling load.
• Scale by the Box3 maximum dimension, then recenter the model on the ground.
• Wrap Z-up BIM models in a Group rotated minus 90 degrees about the X axis.

import { GLTFLoader } from 'three/addons/loaders/GLTFLoader.js';
import { DRACOLoader } from 'three/addons/loaders/DRACOLoader.js';
import { KTX2Loader } from 'three/addons/loaders/KTX2Loader.js';

const draco = new DRACOLoader();
draco.setDecoderPath('https://cdn.jsdelivr.net/npm/three@0.160.0/examples/jsm/libs/draco/');

const ktx2 = new KTX2Loader();
ktx2.setTranscoderPath('https://cdn.jsdelivr.net/npm/three@0.160.0/examples/jsm/libs/basis/');
ktx2.detectSupport(renderer);

const loader = new GLTFLoader();
loader.setDRACOLoader(draco);
loader.setKTX2Loader(ktx2);

loader.load(
  '/models/block-a.glb',
  function (gltf) {
    const model = gltf.scene;
    model.traverse(function (obj) {
      if (obj.isMesh) {
        obj.castShadow = true;
        obj.receiveShadow = true;
      }
    });
    scene.add(model);
  },
  function (event) {
    if (event.total) {
      console.log('加载进度', Math.round(event.loaded / event.total * 100) + '%');
    }
  },
  function (error) {
    console.error('模型加载失败', error);
  }
);

const box = new THREE.Box3().setFromObject(model);
const size = box.getSize(new THREE.Vector3());
const maxDimension = Math.max(size.x, size.y, size.z);
const targetMeters = 120;
const scale = targetMeters / maxDimension;

model.scale.setScalar(scale);
box.setFromObject(model);
const center = box.getCenter(new THREE.Vector3());
model.position.x -= center.x;
model.position.z -= center.z;
model.position.y -= box.min.y;

• Progress totals are missing when the server strips the Content-Length header.
• model.clone shares skeletons, so rigged copies need SkeletonUtils.clone.