threejs-loaders

Use GLTFLoader from three/addons/loaders/GLTFLoader.js and call loader.load with the model URL and a callback. The callback receives a gltf object whose scene property you add to your Three.js scene, and whose animations array can be played with AnimationMixer.

Create a THREE.LoadingManager and pass it to each loader's constructor. Set manager.onProgress to update a progress bar with loaded/total counts, and manager.onLoad to detect when all assets finish loading.

Yes, GLTFLoader supports Draco compression through DRACOLoader. Create a DRACOLoader, set its decoder path to the Draco decoder files, call preload, then attach it with gltfLoader.setDRACOLoader before loading the compressed GLB.

Use RGBELoader to load .hdr files or EXRLoader for .exr files, then set texture.mapping to THREE.EquirectangularReflectionMapping. For PBR rendering, pass the texture through PMREMGenerator.fromEquirectangular before assigning it to scene.environment.

The texture color space is likely wrong. Set tex.colorSpace to THREE.SRGBColorSpace for color and albedo maps, and use linear color space for data maps like normal or roughness textures, then set tex.needsUpdate to true.

Yes, wrap loader.load in a Promise that resolves in the onLoad callback and rejects in onError. You can then await individual loads or use Promise.all to load multiple models and textures concurrently.