Modular texturing for UDK (Questions!)

RossHildick3D

The only way I can see having a really efficient texture atlas for modular environments, is to overlap your UVs. However, I want to create an environment in unreal engine which, unfortunately, doesn't allow overlapping UVs due to artefacts when it comes to building the lighting... So how do you get around this?

Lets say I have a brick texture within my atlas and I want it tiled many times on one of my assets to make the bricks really small... Without overlapping the UVs, its impossible right? so how do people do it?

RossHildick3D

Can someone tell me if I'm way off the mark with this one - What if I just moved the offending overlapping UV shell over to the right/left far enough that it tiles onto where it needs to be; Then it is not overlapping but also a bit messy! (does that matter, really?)

Obscura

You need 2 uv maps. First one can have overlapping or laid out in any way you prefer or satisfies your needs. And then there is a second one used for lightmapping, and that one should not have overlappings.

RossHildick3D

Obscura said:

You need 2 uv maps. First one can have overlapping or laid out in any way you prefer or satisfies your needs. And then there is a second one used for lightmapping, and that one should not have overlappings.

Hi again Obscura, thanks for the reply!

This is uncharted waters for me - Any tutorials you know of that you can firmly shove me in the direction of?

Eric Chadwick

What 3d modeling tool do you use?

RossHildick3D

Eric Chadwick said:

What 3d modeling tool do you use?

Hi Eric, I'll be using Maya for this.

Mirbobo

You can find the light mapping UV documents from https://docs.unrealengine.com/latest/INT/Engine/Content/Types/StaticMeshes/LightmapUnwrapping/

RossHildick3D

I have found this which is giving me a good understanding of the need for lightmaps.
https://www.youtube.com/watch?v=joKnmShAdJE

So its my understandiung that, if ever you have a uv shell that is flipped/inverted/outside of the initial UV space, you need a secondary UV layout for your lightmap? If not, it will just use the existing UVs by default?

Mirbobo

Essentially yes. I usually let Unreal to generate the lightmaps UVs eventho the UV0 would be ok just to make sure there is enough padding in the UV1.

The Polycount wiki has a good amount of tutorials/threads about modular environment workflows that should get you going (given some can be a bit outdated).
http://wiki.polycount.com/wiki/Modular_environments

RossHildick3D

Mirbobo said:

Essentially yes. I usually let Unreal to generate the lightmaps UVs eventho the UV0 would be ok just to make sure there is enough padding in the UV1.

Awesome!

Yeah, I've waded through that a few times now; its stupidly helpful thanks!


Right now I'm trying to figure out how I'd get things like detailed archways and unique sculptures in architecture onto an atlas as it'd obviously have unique normals. The only thing I can think of is having those details as a normal map decal... but that means importing a unique normal map decal for each section which, if im going to be importing a load of maps, makes having an atlas pretty pointless in the first place.

So take this alleyway, for example:
https://www.google.co.uk/maps/@55.9535362,-3.190611,3a,59.9y,270.29h,117.77t/data=!3m6!1e1!3m4!1sArW9WqYFt2h7AnApCW87iA!2e0!7i13312!8i6656

Lets say I wanted all of the architecture seen in this shot on one texture atlas... how would you go about the details on that building on the right?

(thanks so much for the help by the way guys - I learn so much more from you guys than many hours of tutorials!)

Eric Chadwick

You can break down the building details into strips of repeating elements, and stack those strips all together into one atlas, which tiles left-to-right. You could also pack a couple one-off elements into the same atlas.

Then the up/down+left/right tiling textures can be their own separate maps. Brick, stone blocks, etc.

The modular wiki page has lots of info about this. For example, see  Visually Appealing Building Guide and  UE4 Modular Building Set Breakdown.

Making it all into a single atlas is possible, but it places several limits on your workflow. For one thing, you have to add extra edges wherever you want a portion of the atlas texture to tile repeatedly. Or else you have to use extra shader instructions to extract a tile from an atlas.

http://wiki.polycount.com/wiki/Texture_atlas
http://wiki.polycount.com/wiki/ChannelPacking
http://wiki.polycount.com/wiki/MultiTexture

RossHildick3D

http://wiki.polycount.com/wiki/Texture_atlas

http://wiki.polycount.com/wiki/ChannelPacking
http://wiki.polycount.com/wiki/MultiTexture

Thanks, this is super helpful!

I've decided then to make a normal map of just horizontal "trims" and a few sculpts for the decor along the top and have this on a separate UV set. Everything else on the standard UVs for the atlas and also make a third UV set for each module for the lightmap.

Hopefully thats correct :P

Eric Chadwick

No better way to learn than failing.

(I kid!)

RossHildick3D

Hey again!

I was wondering if it is possible to have three UV channels in unreal on an asset? I was hoping to have three - one for diffuse that is unique to this asset, one for a shared normal map across all of my assets, and one for the lightmap.

If no, How do I make sure that unreal engine is using the proper UV set for the lightmap, and not the one for the normals?

I cant find this anywhere online so im thinking maybe you dont have more than two sets?

Eric Chadwick

I moved your thread from Tech Talk to the Unreal Engine section. 

Yes you can have more than 2 UV sets. For example:
https://forums.unrealengine.com/showthread.php?49503-Materials-UV-Channels-and-maps

However I believe the vertex count of each model will increase, which is generally frowned upon when making a real game, since there are memory budgets, and depending on the game the overall download size can also be a factor.

RossHildick3D

No problem, thanks

And yeah I did think that. I cant see any way around it though? Having two maps for the whole level at the cost of vertex count is surely better than lowering that count but having a unique normal map for everything?

RossHildick3D

So I had some time away from this and came back to it. Im having trouble getting my head around something... I wanted to make a "trim sheet" for some detailing on a building. My initial thought, as stated previously, was to have a seperate normal map and have a unique UV set dedicated to those normals... well what if I have a stone material with it own normal map - how can I layer the normals of the stone with the normals of the trim sheet in unreal? or am I going about this the wrong way completely?

Thanks if anyone can help me out with this!¬