Need Help: Shape file with multiple UV maps

[TrainGuy6550]

I'll write it in very simple jargon with a CUBE and avoid the complexity of my real shape altogether.

So suppose a cube with 6 faces (name: CUBE)
1) 3 faces of the cube are assigned Mat 1, and the other 3 are assigned Mat 2.
2) The cube is a single, stitched object with no modifications.
3) Mat 1 has its own UV Map (name: UV_1) for the cube with the 3 faces completely taking up the space of the WORKING AREA of the UV Editor (idk what's that called) and the rest of the faces are out of the WORKING AREA.
4) Mat 2 has its own UV Map (name: UV_2) for the cube's remaining 3 faces completely taking up the space of the WORKING AREA of the UV Editor and the rest of the faces (those that were major in Mat 1) are out of the WORKING AREA.

Now Mat 1 and Mat 2 are present in 2 slots for the SAME object CUBE.
I click on Mat 1, under MSTS Materials, I select the Mat_1 image texture and similarly, for Mat 2, I select the Mat_2 image texture.
I then go to the Shading tab, and select the respective UV maps for each in the UV Map node that the MSTS exporter automatically adds.

When I try to export, the exporter throws an error (maybe an info?!) that my CUBE lacks a UVMap. WTF??? I just manually assigned 2 UV Maps?

Why not just separate the objects (P -> Separate -> Selection)? Becuase it duplicates edges and makes unneeded creases.

What am I trying to do here? Trying to split the texture so that it gets a bigger surface area while keeping the model performant. 4096x4096 textures lag terribly on my computer, so I resort to 512x512, 1024x1024 and 2048x2048 max.
Is that not possible? Is there any alternative / better way of doing it?

Version of the addon I'm using: https://github.com/pwillard/Blender_...ases/tag/4.8.2
Blender: v2.93.18

[superheatedsteam]

From what I recall with exporting .S files, shapes have to have a UV Map called the default 'UVMap' when exporting.

I have just used the default cube in Blender, applied two materials, each using a different texture file, one blue the other red, applied those materials to different faces on the cube exported it OK without error. I opened and viewed the file OK in Shape Viewer. Either post your blender file with a cube with the problem so we can see what you did or I can post my blender cube for your reference to see how I did it. I'm using Blender 4.5.1LTS.

[TrainGuy6550]

Here you go.

[TrainGuy6550]

So, it seems like multiple UV maps are really unsupported. Is there any other hacky way to split a texture for an object into multiple files?

[TrainGuy6550]

Sorry, I forgot to reassign the UV Maps. Here's the corrected version

[pwillard]

Its true. Only the UVMAP named UVMAP will work for the S file export. There are scripts and ADD-ons that can fix this for you. The script is discussed at Elvas Tower and the ADD-ON is available from https://github.com/pwillard/Blender_...tools/releases.

The exporter is rather picky about naming as well. But, this does not mean that you can't assign multiple textures to a single object.

[superheatedsteam]

As Pete noted, you only want to have 1 UV map and it needs to be called UVMap when exporting to .S.

Also both your UV_1 and UV_2 UV maps have 3 faces of the cube out of the UV space boundaries. This is probably not something you want to do as those 3 faces will just be mapped (tiled) to a relative location within the bounds of the UV space.

Try the following to see if this is what you want to achieve:

In the UV Editing tab, with the cube selected in the 3D View port, put the cube into edit mode, face select mode and select all the faces. Then use the – Remove UV Map button to remove the UV_1 and UV_2 UV Maps in the Object Data Properties tab.

With all the faces still selected, click the '+' button to create a new UV Map called UVMap.

Each of the 6 faces will be overlapped and mapped across the entire UV space.

Then select just the 3 faces that have box_tex1 applied and then press 'U' to unwrap those faces. The 3 faces will then be aligned to the left of the UV space. Move/rotate the faces in the UV editor to where you want them on the box_tex1 texture. Then just select the faces that have box_tex2 applied to them and press 'U' to unwrap them. Again they will be mapped to the left side of the UV space. Move/rotate them in the UV Editor where you want them on the box_tex2 texture.

Export the cube as .S to view in shape viewer and the respective faces will be mapped to the respective texture files.

Hope this helps.

[TrainGuy6550]

This works flawlessly, although it is somewhat messy. How do I ONLY select the faces + their respective UV islands of UV_1 without touching UV_2?

The shape file is exported correctly with 1 UVMap and the textures are mapped correctly in the export.

Edit: Nevermind, you select both individually by pressing L (Select Linked) and choosing Material in the bottom left popup.

[pwillard]

Yeah, sometimes Blender lets you do some things the really hard way before you figure out the easy way.