Overlapping UVs poll
polycounter lvl 9
I was having an argument with my co-worker other day about overlapping UVs. We both work in game industry.
We talked about AAA fps and his opition is that overlapping UVs on props are still relevant. (He also likes to not have same texel desity in UVs 
)
) I am trying to prove him he is wrong 
Do you still use overlapping UVs on your models or not?
Replies
If you're giving unique UV space to every single part of every single model you're probably being wasteful with your UV space.
Like Crack said, giving unique space to every UV shell can waste a lot of pixels, cause you to use big textures to get a decent texel density and all of that unique detail might not be required. If you give everything it's own unique space and are dogmatic about texel density you're going to have a lot of large textures that waste a lot of space. But of course that depends on the project and the art style.
Tiling textures and trim sheets exist for a reason. Both of those are stacking UVs. Imagine doing stairs with 100% unique space dedicated to each face, most of them look similar and can use the same texture, maybe offset a little to break up repetition. But again that depends on project and the art style.
If you're doing stairs like this, you can totally use tiling textures and trim sheets.
If you're doing stairs like this that have a ton of unique detail, you're probably going to generate unique textures, at least normal maps.
I also agree with him on texel density. It is a noble goal to strive for a consistent texel density. That is important but not all pieces are created equal, some pieces that just don't need the pixels and eat up a lot of space.
Maybe its a piece that needs to be capped to stop light from leaking into a room, but that cap isn't seen and doesn't need a lot of pixels.
If you go 100% unique unwrap, you end up forcing all of your other (important) pieces to be a little smaller, so a handful of unimportant polys can "technically" be the "correct" texel density, but it ends up hurting the overall piece. What good is checking off a technical rule if it made your stuff look like garbage?
Players don't care about your texel density adherence quotas.
- said no gamer ever
Your boss probably doesn't care either as long as something doesn't stands out egregiously. For players its visually for your boss it's probably visually and technically.
-said the artists ex-boss
You learn why the rules exist, so you can ignore them, when they don't apply. If you just blindly follow rules and apply them to everything all the time, you can end up in a mess that isn't easy to clean up.
On weapons I would beg, borrow, and steal whatever I could to maximize density on shells close to the player’s view.
What, pray tell, are nurnies?
[edit: Oh! They're the same as greebles. I should have known.]
Really, something like a FPS weapon is a good example of an asset that generally should be mapped unique, or at least mostly unique (areas behind the camera without specific handedness detail like butt stocks can sometimes get away with it). For something like a FPV weapon, you should be able to devote enough texture memory to it so that it looks nicely detailed, and doesn't have mirroring artifacts like it's 1999. You'll only ever have the one asset on screen, so memory can be managed in a sensible way (page textures in/out of vram when switching guns).
Though a FPV weapon asset is a good example of when non-uniform texel density can be very helpful. Generally areas further away from the camera or behind the camera should have less density, while focal points or anything like iron sights that the player can zoom in on should have more texel density.