Subsurface Scattering

Implemented a new shader effect, subsurface scattering, that is very important for rendering "plausible" skin. Here is the final result: (ignore the seam at neck + eyes/eyebrows)

Without this effect, here is what the skin looks like:

But this picture isnt exactly representative because even in previous posts, I implemented the easier half of the effect, so it looks more like this:

But even so, the skin is still a bit too harsh so a post processing effect is required to soften it up even further, which brings us to picture #1: