by Yong Li for YafaRay (Yet Another Free Raytracer)
SubSurface Scattering material is very common in daily life, such as jade, marble, and human skin, and a lot of algorithms and models are proposed for rendering this material. However Yafaray still doesn't support this material up to now. So this project will implement subsurface scattering shader for Yafaray, and this shader should work across all Yafaray lighting methods. The main goal of this project is to make user could easily render organic materials, plastics, human skin, etc.