Old-school 3D / fixed-function pipeline emulation with current PBR renderer.

[bryanedds]

A lot of our potential target developers prefer old PSX and PS2 style graphics according to @reinux. Let's see how closely we can emulate that style of rendering by rendering a scene while doing something like the following -

• use black metalness image for all materials
• use gray roughness image for all materials
• use flat normal image for all materials
• use black ambient occlusion image for all materials
• disable ssao
• disable light mapping
• use a pure white sky box

This or something like it should give us a fixed-function like appearance.

[bryanedds]

I think we're satisfied with this as a current capability.