threejs-loaders

## When to use this skill **ALWAYS use this skill when the user mentions:** - `GLTFLoader`, `DRACOLoader`, `KTX2Loader`, `FBXLoader`, `OBJLoader`, progress and error handling - `LoadingManager` for global progress, `Cache` for HTTP caching control - Export: `GLTFExporter`, `OBJExporter`, HDR/KTX2 export pipelines - IES, UltraHDR, or domain-specific loaders listed under Addons Loaders in docs **IMPORTANT: loaders vs textures** - **threejs-loaders** = fetch/decode/parse files into three objects. - **threejs-textures** = `Texture`/`DataTexture` parameters, sampling, PMREM after you already have image buffers. **IMPORTANT: loaders vs dev-setup** - Import path issues belong to **threejs-dev-setup**; this skill assumes imports resolve. **Trigger phrases include:** - "GLTFLoader", "DRACO", "KTX2", "LoadingManager", "export gltf" - "加载模型", "导出", "进度条" ## How to use this skill 1. **Pick loader** by format; prefer glTF for PBR interchange when possible. 2. **Wire LoadingManager** for multi-asset batches; surface `onStart`/`onLoad`/`onProgress`/`onError`. 3. **glTF + Draco**: instantiate `DRACOLoader`, set decoder path, attach to `GLTFLoader.setDRACOLoader` per current docs. 4. **glTF + KTX2**: configure `KTX2Loader` with transcoder path and connect to `GLTFLoader` when using Basis textures. 5. **Export**: use `GLTFExporter` with options matching round-trip needs; note large scenes and binary vs JSON. 6. **Security**: only load user URLs with validation; mention CORS for cross-origin assets. 7. **After load**: traverse scene for materials/meshes—hand off material tuning to **threejs-materials**. See [examples/workflow-gltf-draco.md](examples/workflow-gltf-draco.md). ## Doc map (official) | Docs section | Representative links | |--------------|----------------------| | Core Loaders | https://threejs.org/docs/LoadingManager.html | | Core Loaders | https://threejs.org/docs/GLTFLoader.html | | Addons Exporters | https://threejs.org/docs/GLTFExporter.html | | Addons Loaders | https://threejs.org/docs/DRACOLoader.html | Extended list: [references/official-sections.md](references/official-sections.md). ## Scope - **In scope:** Loader and exporter classes, manager/cache, format choice, plugin wiring for Draco/KTX2, export basics. - **Out of scope:** Server-side transcoding pipelines; physics or game engine asset tooling outside three docs. ## Common pitfalls and best practices - Draco/KTX2 **decoder paths** must match deployed files; broken paths fail silently until onError surfaces. - Duplicate texture instances after merge—consider `renderer.initTexture` implications when cloning materials. - Exporters may not round-trip custom shaders; document limitations. - Always dispose geometries/materials when replacing loaded scenes to avoid GPU leaks. ## Documentation and version Loader and exporter APIs (especially `GLTFLoader` + `DRACOLoader` / `KTX2Loader` wiring) change between three.js versions. Follow [Loaders](https://threejs.org/docs/#Loaders) and **Addons → Loaders / Exporters** in [three.js docs](https://threejs.org/docs/); decoder WASM paths are deployment-specific, not library-version alone. ## Agent response checklist When answering under this skill, prefer responses that: 1. Link `LoadingManager`, `GLTFLoader`, or the relevant format page on https://threejs.org/docs/. 2. Separate **loading** (this skill) from **texture/material tuning** after decode (**threejs-textures**, **threejs-materials**). 3. Document Draco/KTX2 **decoder path** and CORS when assets fail silently. 4. Mention exporter limitations (custom shaders, extensions) honestly. 5. Encourage `dispose()` when replacing entire loaded scenes. ## References - https://threejs.org/docs/#Loaders - https://threejs.org/docs/LoadingManager.html - https://threejs.org/docs/GLTFLoader.html - https://threejs.org/docs/GLTFExporter.html ## Keywords **English:** gltf, gltfloader, dracoloader, ktx2, loadingmanager, cache, exporter, asset pipeline, three.js **中文：** GLTFLoader、加载器、Draco、KTX2、导出、资源、进度、three.js