How to texture a wall using two materials for the inner and otter side?

arkaneXXI

I'm making elements for a modular scene for Unreal Engine and I would like to texture the walls using two different materials, one for the inner side and another one for the outter side. So, I have added a different material ID to every side.
 

The problem is... what's the best way to make the uv mapping and textures for this simple model?

I just can imagine these methods:
1. Make a single UV for the whole mesh and a texture that includes the inner and outer side. The problem of this method is that I need to make a texture for every combination of inner and outter side possible (interior1+exterior1, interior1+exterior2, interior2+exterior1, etc.).
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2. Make a single UV for the whole mesh but every side will have its own texture.
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The problem of this method is that I waste lot of space in the UV.

3. Every side has its own UV and texture while all the wall is in a single mesh. I think this is the best way but I have never seen a model with two different UV in a single mesh. So I'm not sure if this is good or can cause some problems.
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4. The same than the previous method but every side it's in a different mesh. The problem of this method is that it will make the level design slower and complicated. Probably, I'll have snapping problems like this one:


So, my question is, is there a better method to texture a wall with two sides that allows me to put a material to on side and another one to the another side inside Unreal Engine?

srsface

Go with number 3. Sounds like the best for your purposes. It’s totally fine and common to have overlapping UVs in a mesh, especially if they are going to use a different material.

I think for exporting to Unreal you’ll want to have two separate materials already assigned to the mesh in Max. Then the model will end up in the engine with two material slots.

arkaneXXI

srsface said:

Go with number 3. Sounds like the best for your purposes. It’s totally fine and common to have overlapping UVs in a mesh, especially if they need to use a different material.

I think for exporting to Unreal you’ll want to have two separate materials already assigned to the mesh already in Max. Then the model will end up in the engine with two material slots.

Thanks for the tips!

I forgot that sometimes I overlap UVs when doing symmetry (making both identical clusters/isles overlapped). My idea is to make several materials for the same wall and then assign them during the level design to make different type of walls with a single model.

icegodofhungary

You can take one wall modular mesh, assign two materials to it as srsface said, and get two slots in unreal. You can UV that mesh once and use a tiling textures within your separate materials. You don't have to UV map the same wall for 10 different materials if your textures are made correctly. You can just slap them on as needed in unreal.

For example: Let's say you're making several houses. You have two tiling brick textures, and two interior wall textures. You make one modular mesh, UV it so it looks good with any one of your textures/materials. Then, since your other textures are in the same scale as the material you used to UV the mesh, they can just be applied on the fly in unreal as needed. You make the perimeter wall of the house using that modular mesh with a brick on one side, and interior on the other. But then you need a modular piece with interior wall on both sides for the interior walls of the house. So you just place one part of this wall using the existing interior/exterior wall mesh, then drag/apply the interior texture to the brick side on that specific mesh. Now you can duplicate it and do all your interior walls with one mesh. You have used one single mesh to do two types of walls.

If you get worried about your interior walls being too plain, you can use another set of modular meshes for the moulding and other details. You can also build it as a blueprint so you're not having to hand-place the same crown moulding and wainscotting for every piece of the wall in-level.

Even more so is you can design your textures to incorporate trim pieces so that you get both a texture for your baseboard or moulding and a tiling texture in one go. Like this:

https://polycount.com/discussion/144838/ue4-modular-building-set-breakdown/p1

The project above is available on the Unreal marketplace for free, I recommend downloading it and taking a look. It's about 2GB in total.

https://www.unrealengine.com/marketplace/en-US/product/modular-building-set

If you download other free example content you'll get a better sense how textures are used. You realize how much you can do with very little.