As someone who has seen this effect before, but was unclear how it was done, this article is very "and now draw the rest of the owl". They define a basic equation, it's about what I expected, but the end shader code doesn't use it in that form, and I found it pretty difficult to parse, I can't say I'm much better off in the end.

What I usually do in 2026 is copy the code and article and have Claude clarify the unclear parts for me. then is ok.