Add Gouraud / per vertex shader support through the scene's lightloop

With PBR standardizing through things like Material X, it would make sense to also preserve older workflows. Gouraud shading specifically, through EEVEE. Especially since some workflows stopped working after 2.79.

The reason for the why:

People try to go for a certain look but will never be able to achieve it in modern EEVEE.

Currently we can reach newer heights in a real-time workflow, great. But certain stylistic workflows are being ignored as a consequence.

With Blender being more accessible since 2.8, it would have of course been beneficial to give people who come from a disadvantaged background an opportunity to touch on this tech without having to miss out on the current feature sets.

How would this be able to be implemented? I once read that the implementation would be difficult because it would have to create a new element to the buffer and of course, buffers are expensive.

What we would gain from it: Currently the biggest userbase that would use this kind of shading works in a low poly art style, it's more popular than ever, from people like:

Mallbat ( youtube.com/channel/UC9OFDumeHCcZfzUKZW8F7gw ),

Lee Griffin ( instagram.com/its_lit_lee/ )

and Nam Mac ( instagram.com/lordstingray/ )

I do not wish to imply that they would absolutely use such a feature but I believe that the renaissance of a nostalgic 3D workflow can evolve into something more if we give the opportunity to fall back to the things we back then, considered 'peak technology'. We can now do things we could not back then with the current tech.