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Blender import: 1 UV for entire model vs 1 per material. Validation needed (+ why model so dark?)

Greetings,

The following Blender model needs to be exported to Unreal - see first screenshot.

The 2 workspace files are available in the following zip:
https://new.dercetech.com/wp-content/uploads/2019/10/model_export_from_blender_one_or_many_uvs.zip

The second screenshot is the import result of option 1 (left, bad) vs option 2 (right, good)

I started with the “option 1”: having one UV Map per material.
Main steps:

  • attempt to have no more than one material per mesh
  • assign the same UV Map name to objects that use a similar material so that when joining the objects, meshes using the same material will have an identical UV Map.
  • join the meshes
  • for each material, add an UV Map input pointing to the right map.
  • export fbx
  • import in Unreal: bad result, only one material is rendered

Result: Only one material is rendered.

Option 2: having one UV Map for the entire model
Main stemps:

  • same
  • assign the same uv map name to all meshes
  • join meshes
  • no need to add input uv maps to materials
  • export fbx
  • import in Unreal: good result, every material is rendered

So I’m obviously tempted to think option 2 is good.

Is it really a good practice to have to assign the same name to all uv maps before joining the meshes in Blender? I’m too unexperienced to foresee the problems / limitations of this approach.

Moreover, secondary question: why is my “good import” so dark? It’s supposed to be worn by a character, so I understood it doesn’t need a “lightmap”. I’d be thankful you could fingerpoint at what I’ve done wrong :slight_smile:

NB regarding the workspaces linked above. There’s two of them, each have:

  • a collection of separate meshes
  • a collection containing the joined mesh based on the option 1 or option 2 technique
  • both have some texture / material / cleanup / etc. python scripts I wrote to ease the renaming of UV Maps, meshes, etc.

Thanks a lot for your attention!