Micro Scratch Shader

There’s an amazing article by Hang Li that talks about how to make the “swirl micro scratch” look(in Chinese). Simply put, the theory is to match the scratch stroke direction with anisotropic direction. The approach used in the article is by file texture. Here I implemented a procedural shader that generate proper texture for you.

Source code and example scenes: https://github.com/cuckon/scratched

And here’s how the result looks:

Besides the physical swirl scratch specular, you can achieve some interesting look by tweaking the “offset” parameter:

And it’s very easy to be used in Clarissa or Arnold or any other DCC that support OSL:

For detail and source code and example scene, take a look at the github link I gave above.