So as the title says, I’d really like a good explanation of how the tangent input on a Hair Shader even works. tried pluging in a normal map, tried the derivative of the normal map can’t for the life of me figure it out and really I haven’t seen anything that even attempts to explain it. I’d really like to start experimenting with it but I can’t really do anything with it so far since I don’t even know how to use it.
I would also like to know…bump
The tangent is just a vector along which the specular lobes will lie. As with any anisotropic material, you’ll want to specify which direction (U or V) the highlight is to stretch. Make a 3 constant with 0,1,0 and plug that in to have the spec stretch along the U axis.
basically you can use anything to author your vectors. They should point along the direction of the strand.
https://support.allegorithmic.com/documentation/display/SPDOC/Flow+map+painting