Hair rendering in Nvidia's "A New Dawn' demo

[zhugel_007]

Hi,

The hair in Nvidia's 'A New Dawn' demo looks amazing. But I couldn't find any document online that explains how it was done.

After taking a capture, it seems that the hair geometry is entirely generated from Domain/Hull /Geometry shader. Lighting seems using deferred light with alpha test only(I guess it is to avoid sorting problem.). Lighting mode doesn't look like Marschner because I couldn't find the typical Marschner textures.

Anyone has more detailed information on the way of shading the hair in this demo? I am very interested in the lighting model it is using, and how the back lighting for the hair is done.

 

[Davros]

quote]“Because hair is so thin, aliasing is a major problem. Traditional antialiasing doesn't work well here, as a strand is often smaller than a pixel and may not be picked up by any of the four-or-so sample points. To alleviate this problem, A New Dawn has a special hair smoothing shader that inspects each strand and blurs them in the combing direction.[/quote]
https://developer.nvidia.com/sites/default/files/akamai/gamedev/files/sdk/11/HairSDKWhitePaper.pdf


something related
http://www.techpowerup.com/180675/amd-tressfx-technology-detailed.html

 

[zhugel_007]

Thanks for the reply.
I agree the hair generation part is probably following the 1st paper. the shading in Tomb Raider is the same as the AMD Ruby demo in 2004, cheap fake of Marschner. They are using OIT to solve the sorting problem which is a bit overkill in my opinion. My feel is that in the New Dawn demo, they are using something else for the shading part.

 

[NThibieroz]

You will find that "cheap" solution to approximate hair strand transparency such as blurring or even MSAA have a dramatic impact on image quality. You may get away with it if you hair is fully black but other hair colors will suffer greatly.