Mipmap selection in too much detail

Totally fantastic article. I don't do work that overlaps with this at all, but even after 37+ years as a C++ programmer, I found this enlightening, engaging and informative. Thank you very much.

Great writeup!

I can't tell from your GLSL if these would have forced FMAs for a lot of the intermediate product sums. That would probably be a non-trivial effect, particularly for your large anisotropy cases.

The Heckbert paper also describes the basic theory, but you would want to supplement with some of the offline rendering work that followed it. OpenImageIO (OIIO) is pretty widely used, and has gone through several iterations of bug fixing like https://github.com/AcademySoftwareFoundation/OpenImageIO/pul...

But for your purposes, you probably just need to find all the magic epsilons and sign checks to make it match.

There simply isn't another way to access registers from one 'thread' on another thread without using an intrinsic. You need that to calculate finite differences. For a long time, the only option was ddx()/ddy(). Now we also wave intrinsics, which you couldn't implement yourself either.