Comment by jms55

There is no standard.

Filament is extremely well documented: https://google.github.io/filament/Filament.html

glTF's PBR stuff is also very well documented and aimed at realtime usage: https://www.khronos.org/gltf/pbr/

OpenPBR is a newer, much more expensive BRDF with a reference implementation written in MaterialX that iirc can compile to glsl https://academysoftwarefoundation.github.io/OpenPBR

Pick one of the BRDFs, add IBL https://bruop.github.io/ibl, and you'll get decent results for visualization applications.