jkuhlmann/cgltf

Free

:diamond_shape_with_a_dot_inside: Single-file glTF 2.0 loader and writer written in C99

FreeFree tier

Type

Open Source

Visit Website GitHub (38 stars)

About jkuhlmann/cgltf

cgltf is a single-file, stb-style C99 library for loading and writing glTF 2.0 files. It supports both glTF (JSON) and glb (binary) formats, including meshes, accessors, buffer views, buffers, materials, textures, samplers, images, scenes, nodes, skins, animations, cameras, morph targets, and extras data. The library also supports several glTF extensions such as EXT_mesh_gpu_instancing, EXT_meshopt_compression, EXT_texture_webp, and KHR_draco_mesh_compression (requires an external library). It is used in popular projects like bgfx, Filament, gltfpack, raylib, and Unigine. Loading can be done from file or memory, and writing is similarly supported. cgltf does not automatically load external buffer or image files; users must handle those or call cgltf_load_buffers for buffer data. The writer does not output external buffer or image data either.

Key Features

Single-file, stb-style integration, requiring only one .h file

Supports both glTF (JSON) and glb (binary) file formats

Core glTF 2.0 support: meshes, materials, scenes, nodes, skins, animations, cameras, morph targets, extras

Extension support: EXT_mesh_gpu_instancing, EXT_meshopt_compression, EXT_texture_webp, KHR_draco_mesh_compression

Loading from file or memory

Writing to file or memory

cgltf_load_buffers helper to open and read buffer files (including base64 data URIs)

Used in major open-source projects like bgfx, Filament, gltfpack, raylib, Unigine

Pros & Cons

Pros

Single-file header – easy to drop into any C/C++ project
Supports a wide range of core glTF 2.0 features and popular extensions
Lightweight and minimal dependencies (standard C library only)
Proven in production by several well-known projects
Both loading and writing are provided in a consistent API

Cons

Does not automatically load external buffer or image files; user must handle file I/O or use helper functions
Writer does not output external buffer or image data either
Draco mesh compression support requires an external library
Only supports glTF 2.0; no support for older glTF versions

Best For

Loading glTF 2.0 3D models into game engines or rendering applicationsWriting glTF 2.0 assets programmaticallyIntegrating glTF support into C/C++ tools and pipelinesEducation and prototyping with minimal dependencies

FAQ

What glTF extensions does cgltf support?

cgltf supports EXT_mesh_gpu_instancing, EXT_meshopt_compression, EXT_texture_webp, and KHR_draco_mesh_compression (the latter requires an external library).

Does cgltf automatically load buffer and image files?

No. By default cgltf only parses the glTF descriptor. You must load buffer and image files yourself using URIs from data.buffers[] or data.images[]. Alternatively, cgltf_load_buffers can open and read buffer files via FILE* APIs, and cgltf_load_buffer_base64 can decode base64 data URIs in images.

Is cgltf used in any well-known projects?

Yes, cgltf is used in bgfx, Filament, gltfpack, raylib, and Unigine, among others.