Header only C++ tiny glTF library(loader/saver).

TinyGLTF is a header only C++11 glTF 2.0 https://github.com/KhronosGroup/glTF library.

TinyGLTF uses Niels Lohmann's json library (https://github.com/nlohmann/json), so now it requires C++11 compiler. (Also, you can use RadpidJSON as an JSON backend) If you are looking for old, C++03 version, please use devel-picojson branch (but not maintained anymore).

Status

Currently TinyGLTF is stable and maintenance mode. No drastic changes and feature additions planned.

• v2.8.0 Add URICallbacks for custom URI handling in Buffer and Image. PR#397
• v2.7.0 Change WriteImageDataFunction user callback function signature. PR#393
• v2.6.0 Support serializing sparse accessor(Thanks to @fynv).
• v2.5.0 Add SetPreserveImageChannels() option to load image data as is.
• v2.4.0 Experimental RapidJSON support. Experimental C++14 support(C++14 may give better performance)
• v2.3.0 Modified Material representation according to glTF 2.0 schema(and introduced TextureInfo class)
• v2.2.0 release(Support loading 16bit PNG. Sparse accessor support)
• v2.1.0 release(Draco decoding support)
• v2.0.0 release(22 Aug, 2018)!

Branches

• sajson : Use sajson to parse JSON. Parsing only but faster compile time(2x reduction compared to json.hpp and RapidJson), but not well maintained.

Builds

Features

Probably mostly feature-complete. Last missing feature is Draco encoding: syoyo#207

• Written in portable C++. C++-11 with STL dependency only.
  • macOS + clang(LLVM)
  • iOS + clang
  • Linux + gcc/clang
  • Windows + MinGW
  • Windows + Visual Studio 2015 Update 3 or later.
    • Visual Studio 2013 is not supported since they have limited C++11 support and failed to compile json.hpp.
  • Android NDK
  • Android + CrystaX(NDK drop-in replacement) GCC
  • Web using Emscripten(LLVM)
• Moderate parsing time and memory consumption.
• glTF specification v2.0.0
  • ASCII glTF
    • Load
    • Save
  • Binary glTF(GLB)
    • Load
    • Save(.bin embedded .glb)
• Buffers
  • Parse BASE64 encoded embedded buffer data(DataURI).
  • Load .bin file.
• Image(Using stb_image)
  • Parse BASE64 encoded embedded image data(DataURI).
  • Load external image file.
  • Load PNG(8bit and 16bit)
  • Load JPEG(8bit only)
  • Load BMP
  • Load GIF
  • Custom Image decoder callback(e.g. for decoding OpenEXR image)
• Morph traget
  • Sparse accessor
• Load glTF from memory
• Custom callback handler
  • Image load
  • Image save
• Extensions
  • Draco mesh decoding
  • Draco mesh encoding

Note on extension property

In extension(ExtensionMap), JSON number value is parsed as int or float(number) and stored as tinygltf::Value object. If you want a floating point value from tinygltf::Value, use GetNumberAsDouble() method.

IsNumber() returns true if the underlying value is an int value or a floating point value.

Examples

• glview : Simple glTF geometry viewer.
• validator : Simple glTF validator with JSON schema.
• basic : Basic glTF viewer with texturing support.
• build-gltf : Build simple glTF scene from a scratch.

WASI/WASM build

Users who want to run TinyGLTF securely and safely(e.g. need to handle malcious glTF file to serve online glTF conver), I recommend to build TinyGLTF for WASM target. WASI build example is located in wasm .

Projects using TinyGLTF

• px_render Single header C++ Libraries for Thread Scheduling, Rendering, and so on... https://github.com/pplux/px
• Physical based rendering with Vulkan using glTF 2.0 models https://github.com/SaschaWillems/Vulkan-glTF-PBR
• GLTF loader plugin for OGRE 2.1. Support for PBR materials via HLMS/PBS https://github.com/Ybalrid/Ogre_glTF
• TinyGltfImporter plugin for Magnum, a lightweight and modular C++11/C++14 graphics middleware for games and data visualization.
• Diligent Engine - A modern cross-platform low-level graphics library and rendering framework
• Lighthouse 2: a rendering framework for real-time ray tracing / path tracing experiments. https://github.com/jbikker/lighthouse2
• QuickLook GLTF - quicklook plugin for macos. Also SceneKit wrapper for tinygltf.
• GlslViewer - live GLSL coding for MacOS and Linux
• Vulkan-Samples - The Vulkan Samples is collection of resources to help you develop optimized Vulkan applications.
• TDME2 - TDME2 - ThreeDeeMiniEngine2 is a lightweight 3D engine including tools suited for 3D game development using C++11
• SanityEngine - A C++/D3D12 renderer focused on the personal and professional development of its developer
• Open3D - A Modern Library for 3D Data Processing
• Supernova Engine - Game engine for 2D and 3D projects with Lua or C++ in data oriented design.
• Wicked Engine - 3D engine with modern graphics
• Your projects here! (Please send PR)

TODOs

• Robust URI decoding/encoding. syoyo#369
• Mesh Compression/decompression(Open3DGC, etc)
  • Load Draco compressed mesh
  • Save Draco compressed mesh
  • Open3DGC?
• Support extensions and extras property
• HDR image?
  • OpenEXR extension through TinyEXR.
• 16bit PNG support in Serialization
• Write example and tests for animation and skin

Optional

• Write C++ code generator which emits C++ code from JSON schema for robust parsing?

Licenses

TinyGLTF is licensed under MIT license.

TinyGLTF uses the following third party libraries.

• json.hpp : Copyright (c) 2013-2017 Niels Lohmann. MIT license.
• base64 : Copyright (C) 2004-2008 René Nyffenegger
• stb_image.h : v2.08 - public domain image loader - Github link
• stb_image_write.h : v1.09 - public domain image writer - Github link

Build and example

Copy stb_image.h, stb_image_write.h, json.hpp and tiny_gltf.h to your project.

Loading glTF 2.0 model

// Define these only in *one* .cc file.
#define TINYGLTF_IMPLEMENTATION
#define STB_IMAGE_IMPLEMENTATION
#define STB_IMAGE_WRITE_IMPLEMENTATION
// #define TINYGLTF_NOEXCEPTION // optional. disable exception handling.
#include "tiny_gltf.h"

using namespace tinygltf;

Model model;
TinyGLTF loader;
std::string err;
std::string warn;

bool ret = loader.LoadASCIIFromFile(&model, &err, &warn, argv[1]);
//bool ret = loader.LoadBinaryFromFile(&model, &err, &warn, argv[1]); // for binary glTF(.glb)

if (!warn.empty()) {
  printf("Warn: %s\n", warn.c_str());
}

if (!err.empty()) {
  printf("Err: %s\n", err.c_str());
}

if (!ret) {
  printf("Failed to parse glTF\n");
  return -1;
}

Loader options

• TinyGLTF::SetPreserveimageChannels(bool onoff). true to preserve image channels as stored in image file for loaded image. false by default for backward compatibility(image channels are widen to RGBA 4 channels). Effective only when using builtin image loader(STB image loader).

Compile options

• TINYGLTF_NOEXCEPTION : Disable C++ exception in JSON parsing. You can use -fno-exceptions or by defining the symbol JSON_NOEXCEPTION and TINYGLTF_NOEXCEPTION to fully remove C++ exception codes when compiling TinyGLTF.
• TINYGLTF_NO_STB_IMAGE : Do not load images with stb_image. Instead use TinyGLTF::SetImageLoader(LoadimageDataFunction LoadImageData, void *user_data) to set a callback for loading images.
• TINYGLTF_NO_STB_IMAGE_WRITE : Do not write images with stb_image_write. Instead use TinyGLTF::SetImageWriter(WriteimageDataFunction WriteImageData, void *user_data) to set a callback for writing images.
• TINYGLTF_NO_EXTERNAL_IMAGE : Do not try to load external image file. This option would be helpful if you do not want to load image files during glTF parsing.
• TINYGLTF_ANDROID_LOAD_FROM_ASSETS: Load all files from packaged app assets instead of the regular file system. Note: You must pass a valid asset manager from your android app to tinygltf::asset_manager beforehand.
• TINYGLTF_ENABLE_DRACO: Enable Draco compression. User must provide include path and link correspnding libraries in your project file.
• TINYGLTF_NO_INCLUDE_JSON : Disable including json.hpp from within tiny_gltf.h because it has been already included before or you want to include it using custom path before including tiny_gltf.h.
• TINYGLTF_NO_INCLUDE_RAPIDJSON : Disable including RapidJson's header files from within tiny_gltf.h because it has been already included before or you want to include it using custom path before including tiny_gltf.h.
• TINYGLTF_NO_INCLUDE_STB_IMAGE : Disable including stb_image.h from within tiny_gltf.h because it has been already included before or you want to include it using custom path before including tiny_gltf.h.
• TINYGLTF_NO_INCLUDE_STB_IMAGE_WRITE : Disable including stb_image_write.h from within tiny_gltf.h because it has been already included before or you want to include it using custom path before including tiny_gltf.h.
• TINYGLTF_USE_RAPIDJSON : Use RapidJSON as a JSON parser/serializer. RapidJSON files are not included in TinyGLTF repo. Please set an include path to RapidJSON if you enable this feature.
• TINYGLTF_USE_CPP14 : Use C++14 feature(requires C++14 compiler). This may give better performance than C++11.

CMake options

You can add tinygltf using add_subdirectory feature. If you add tinygltf to your project using add_subdirectory, it would be better to set TINYGLTF_HEADER_ONLY on(just add an include path to tinygltf) and TINYGLTF_INSTALL off(Which does not install tinygltf files).

// Your project's CMakeLists.txt
...

set(TINYGLTF_HEADER_ONLY ON CACHE INTERNAL "" FORCE)
set(TINYGLTF_INSTALL OFF CACHE INTERNAL "" FORCE)
add_subdirectory(/path/to/tinygltf)

Saving gltTF 2.0 model

• Buffers.
  • To file
  • Embedded
  • Draco compressed?
• Images
  • To file
  • Embedded
• Binary(.glb)
  • .bin embedded single .glb
  • External .bin

Running tests.

glTF parsing test

Setup

Python required. Git clone https://github.com/KhronosGroup/glTF-Sample-Models to your local dir.

Run parsing test

After building loader_example, edit test_runner.py, then,

$ python test_runner.py

Unit tests

$ cd tests
$ make
$ ./tester
$ ./tester_noexcept

Fuzzing tests

See tests/fuzzer for details.

After running fuzzer on Ryzen9 3950X a week, at least LoadASCIIFromString looks safe except for out-of-memory error in Fuzzer. We may be better to introduce bounded memory size checking when parsing glTF data.

Third party licenses

• json.hpp : Licensed under the MIT License http://opensource.org/licenses/MIT. Copyright (c) 2013-2017 Niels Lohmann http://nlohmann.me.
• stb_image : Public domain.
• catch : Copyright (c) 2012 Two Blue Cubes Ltd. All rights reserved. Distributed under the Boost Software License, Version 1.0.
• RapidJSON : Copyright (C) 2015 THL A29 Limited, a Tencent company, and Milo Yip. All rights reserved. http://rapidjson.org/
• dlib(uridecode, uriencode) : Copyright (C) 2003 Davis E. King Boost Software License 1.0. http://dlib.net/dlib/server/server_http.cpp.html