I'm having some problems "downgrading" some textures from PBR to the traditional workflow, with diffuse, spec and normal. I just can't put the lighting information back into the diffuse. Should i generate an AO and put on top of it?
This is super hacky but when using Spec/Gloss PBR I had to use a metalness mask to mask off the parts of the specular map to replace parts of the diffuse map since metals on pbr spec/gloss are black. Then there were a few levels adjustments/etc and it worked pretty well.