To create rich and interactive 3D experiences in your React apps with Three.js, you often need to go beyond basic shapes and materials. This is where external models and textures come into play. Three.js provides dedicated loaders for importing a wide range of 3D model formats and textures, making it possible to bring complex assets into your scenes.

The most commonly used model loader in modern Three.js projects is the GLTFLoader, which supports the glTF format—a compact, efficient, and widely adopted standard for 3D models. glTF supports meshes, materials, animations, and even cameras. For older or simpler models, you might use the OBJLoader, which imports OBJ files but typically requires a separate material loader for textures.

Textures, which add detail and realism to your models, are loaded using the TextureLoader. This loader can import standard image formats like PNG and JPEG, allowing you to wrap images around your 3D geometry or models.

When you use a loader, you provide the path to your asset file, and the loader returns a ready-to-use Three.js object or texture. This process is asynchronous, which means your app can keep running while assets are being loaded. Loaders often provide progress and error callbacks, so you can show loading indicators or handle problems gracefully.

Once your assets are loaded, the next step is to integrate them into your React-managed Three.js scene. In a React app, you typically load models and textures inside a useEffect hook to ensure they load when your component mounts. You store the loaded asset in React state, and then use that state to add the asset to your Three.js scene graph. This approach keeps your asset management in sync with React's lifecycle, so updates and clean-up happen automatically.

By using loaders and integrating assets through React state and effects, you can efficiently manage complex scenes, keep your UI responsive, and deliver high-quality 3D experiences.