collection of tools for working with tetrahedra (3d simplex)

The main feature is tetrahedrasation (triangulation in 3d space)

### Optimization

Optimize tetrahedrons to reduce number of thin and long tetras ([link](https://gitlab.onelab.info/gmsh/gmsh/-/blob/master/contrib/hxt/tetMesh/src/HXTSPR.c))

## lighting
[Ray-Traced Irradiance Fields (Presented by NVIDIA)](https://www.youtube.com/watch?v=KufJBCTdn_o)
https://www.youtube.com/watch?v=pYY7iiVkyYE


References
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[Wikipedia - Delaunay triangulation](https://en.wikipedia.org/wiki/Delaunay_triangulation)
