Question about making or not making texture sheets for UT3

Hayden Zammit

I'm on team working on a mod for UT3. I've just got a question about the best way to use texture sheets.

I'm used to using one model per texture sheet. Is this an okay way to do it? I mean will it cause any problems. I know in cases Epic have used texture sheets for meshes in UT3, but it seems they don't always. Is it alright to just have one mesh per sheet?



cheers.

PieJesu

In my experience with the Source Engine, textures are a major factor in the performance of the game. It's starting to get to the point where things are no longer transform bound, but fill bound.

If you can have more than one mesh on a single texture sheet then you're doing good. Say, a map you're working on has many different rock shapes required. You're going to have lots of rocks but, why waste memory by having a different sheet for each rock. It's pretty easy to get them patched to the same sheet thus reducing the amount of memory required.

Also, if you don't think you can get away with just a diffuse map, keep it that way. No need for unnecessary detail in highly populated scenes, especially for smaller objects.


Basically, if you have numerous small meshes that you know will be used on the same map, just keep it to a single sheet for all of them. It's no harm, shouldn't cause any problems.

sprunghunt

Texture atlasing/sheets doesn't matter in UT3 since each object is a new batch anyway. Just avoid putting more than one material on a single mesh.

Ott

Speaking of small meshes or background props, it's pretty easy to finagle a very simple specular using just your diffuse if you want to save time / memory. Using a desaturate / multiply / vector combination can give you some passable specularity on some of your props, and save you the memory and time of creating a brand new spec map.

Obviously it depends on your object, but that might give you some extra memory. Also, learn about using the different channels for your maps, and if you can get away with using just black and whites you can always use multiple channels of a targa file. (Keep in mind each channel will compress differently, but if you can get 3-for-1 out of your "spec" that's always going to be better than creating brand new maps when reusability is an option)

cman2k

texture re-use and sharing across meshes is great, but the only savings there is texture memory savings. This doesn't affect the transform-bound/fill-bound issue that was brought up.

If you have rock A and rock B, they are both going to be seperate batch/draw calls to the GPU, regardless of whether or not they share a texture.

As sprunghunt said, avoid using multiple textures/materials per-mesh and you should be alright on the fill-bound issue. Otherwise, your efforts are just going towards saving texture memory (which may or may not be necessary or impact your performance, depending on your usage).

PieJesu

cman2k wrote: »

This doesn't affect the transform-bound/fill-bound issue that was brought up.

Ah, yeah, I see.

Hayden Zammit

Ah, thank you all for the info.

This may seem silly, but if I want a bunch of models to share the same texture sheet does that mean my work flow should bear that in mind? A lot of the time I'll finish a mesh and UV map it so it uses up as much space as possible. I usually then texture. But then if I were to make another mesh that I wanted on the same texture sheet as the previous model I'd made does that mean I have to go and re-size all the UVs so that both meshes fit the one sheet? Is there any easy way to do this?


cheers.

ImSlightlyBored

yeah you just need to consider it when making a mesh, thats the easiest way to do it (theres probably/there is a way to cut a tex page up in the shader but why go so complicated?)
what I do is create a texture sheet of the size i want, visibly cut it in to 4, then when I'm UV'ing, use it as a template. Probably best to stick to square sections of map just in case you later want to expand it to a single map by scaling up and so on

does that make sense, I have a bad feeling ti doesnt.

Hayden Zammit

Yeah, I'm a little lost with it all, sorry. It just seems like its going to be a hell of a lot of hassle if I have to go back and arrange everything onto sheets. We're using UT3 editor by the way.