Arvīds KokinsDec 6, 2024

Was thinking again a while ago what waste PBR textures can be under most lighting.

Kind of weird to do a 4x texture memory increase - assuming BC1-5 and no alpha/metalness, e.g. BC1 base color + BC5 normal map & BC4 roughness - that will only show up under specific lighting conditions and elsewhere appears flat.

Though doubling texture resolution in both dimensions is also a 4x increase that might never show up (esp. with upscaling) so all things considered, maybe 4x isn't that bad.

#gamedev

Show threadMatt PettineoDec 7, 2024
@archo I’m not sure what you mean by this, all of your typical “PBR” maps will be active in all lighting scenarios unless you literally have no lighting.
Show threadArvīds KokinsDec 8, 2024

@mjp I meant that it would be possible to replicate huge chunks of scenes even with the PBR textures removed (may need baking/keeping lighting into the color map aka old-school diffuse maps).

Depends on the game and the scene of course but most materials have high roughness and a good amount of games have lots of heavily shadowed areas or cloudy/foggy skies.

Attached some examples where the numerous flat-appearing areas should be easily visible:

Show threadMatt PettineoDec 8, 2024
@archo those two scenes would look wildly different without roughness/normal/maps, and *especially* if you dropped specular entirely. Even if you had infinite resolution baked diffuse response through VT or similar they wouldn’t look the same, and you’d have no ability to do dynamic lighting.
Show threadMatt PettineoDec 8, 2024
@archo the whole “wet look” of the road in the left screenshot is coming from normal and roughness maps. I’m not sure how you would replicate that with just diffuse. Or even if you could, it would surely not look right from multiple view angles.
Show threadArvīds KokinsDec 8, 2024

@mjp I'm not saying that the entire screenshot/scene doesn't benefit from PBR textures, just that there are huge parts that don't - for example, the walls in the first screenshot and grass/most trees in the second one.

My note on diffuse baking was about being able to assume that lighting will generally come from known average directions, which allows the normal map to be baked into base color with hard-to-notice loss assuming (near-)max roughness (e.g. for the characters in the screenshots).

Show threadMatt PettineoDec 9, 2024
@archo I very much doubt that assumption would hold for all viewing angles or lighting conditions in which that wall material ends up getting used. Grass has tons of specular, especially up close! Very few materials have effectively no noticeable specular, especially at grazing angles.
Show threadMatt PettineoDec 9, 2024
@archo if you were to bake lighting/normals into the color map you would effectively be having a gigantic combinatorial explosion on your texture sizes, MegaTexture-style. That's a very tough pill to swallow for all kinds of reasons, both in terms of dev workflow and end user experience. People already complain about filling up their HDDs. Which is why that idea of shipping unique VTs never went anywhere post-Rage.
Show threadMatt Pettineo
@archo VT page generation at runtime is very much a thing though, since you still get the massive compression benefit of shipping tiling textures that can be used over and over again throughout the game. But even then the VT system will still spit out normal + roughness maps, since you want that for dynamic lighting. Or you can go even further and do full texture-space shading using the bones of a runtime VT system.
Dec 9, 2024 at 12:22amWeb