It utilizes vertex colours RGBA to mask out areas of hair and give the user the ability to specify a colour and how strong the effect is.
It can be used to subtlety add variation or strongly for stylized visuals.
Works well with an already existing albedo texture, or can work with a flat colour as well.
Ideally would benefit most with a grey scale albedo texture with variation in lights and darks, with the overall tone around 128 grey, similar to a detail map.
Feel free to throw some $ at this, as it will help support me in creating more custom shaders that will benefit artists.
Example of shader in use - https://www.youtube.com/watch?v=LrxzEM8p1gw
Portfolio - https://www.artstation.com/codyalday
Email if any issues - email@example.com