TGen

This is a very basic tangent generator, written in C++. The main purpose of this project is to facilitate adoption of, and discussion about, the proper setup of tangent spaces for glTF 2.0 assets.

Current Features:

Generation of per-corner tangents for triangle data with UVs
Computation of per-wedge / per-UV-vertex tangent spaces
Tangent frame orthogonalization
Encoding of 4-component tangents (with "flip factor") for avoiding explicit bitangents
Simple C++ implementation, no dependencies
Compilable to asm.js and WebAssembly (right now, only the functions are exported, there is no web demo yet)

The code consists basically of one header + .cpp file. For debugging and visualization, there is also a simple X3D exporter in a separate file, which was used to generate the 3D visualizations shown below. The baked tangent-space normal maps are just provided for demonstration purposes, the actual baking code is not part of this repository.

So far, the C++ code from this project has been compiled and tested with VS 2015, gcc 6.3 / 7.0 trunk, clang 5.0 trunk and emscripten 1.37 (clang 3.9).

Feedback and contributions are always welcome.

Building and installing

TGen has no external dependencies and can be built using CMake 3.4 or newer:

cd <this-repo>
mkdir build
cd build

# Native targets
cmake .. [-DCMAKE_BUILD_TYPE=Release] [-DTGEN_STATIC_LIBRARY=0] # Default is building as a shared library
cmake --build . [--target install]

# Emscripten
emconfigure cmake .. [-DCMAKE_BUILD_TYPE=Release] [-DTGEN_WEBASSEMBLY=1] # Default is asm.js instead of WebAssembly
cmake --build .
emrun --port 8080 bin