I was hoping to be able to set faces to specific material index and use the node to separate node flow within the same material, but I can’t find a way to do it. The material index in the solidify modifier works by assigning different material slots, which seems the same as assigning faces to different materials.
Maybe it’s not possible? If not possible, what on earth is it supposed to do then?
My idea was to have anisotropic shading along some faces and turn off anisotropy for other faces, but all in the same material slot. So if my “per face assigned material index” was 0, material sets some anisotropy value, for remaining faces material turns off anisotropy.
I’ve found a way around it by UV location checking (my isotropic faces will be in the top of my UVs), but I’m still interested in knowing what the intended use for the node is.