Question FBX export/import only supports Vector2 in UV (but the uvs can contain upto Vector4 in Unity)

Hi, I have a procedurally generated mesh in Unity, and I have some Vector4 data stored in UV3 and UV4 that I use for custom shader effects. All is well within the Unity editor, but I want to save the mesh so that I don't have to generate it every time for performance reasons. I tried saving to FBX with the FBX exporter, and importing the resulting FBX. Now, all the UV channels only have Vector2s and I lose half my data.

I don't know if this is a limitation of the FBX file format, the FBX exporter, or the FBX importer.
I'd love to hear thoughts from someone who might know more.

Alternately, is there another file format, where I can save Vector4 in UV channels (or a format that supports arbitrary vertex streams)?

Thanks

 

Hi! It looks like this might currently be a limitation of FBX, which uses Vector2 for the UVs:
https://help.autodesk.com/view/FBX/2017/ENU/?guid=__cpp_ref_class_fbx_layer_element_u_v_html
(FbxLayerElementUV based on FbxLayerElementTemplate<FbxVector2>)

It might be possible to include the additional data as extra information in the FBX, however I don't think it would be loaded by the Unity importer (would potentially need to write a custom importer).

If you do not need to transfer the data to a different software, an alternative could be saving the Mesh into the Unity .asset format: https://docs.unity3d.com/ScriptReference/AssetDatabase.CreateAsset.html

 

@vkovec Thanks! Saving to an *.asset file works wonderfully, and I found a github to do just that:
https://github.com/pharan/Unity-MeshSaver

Btw, do you know if there's a way to use a different extension for this asset? That would help configuring git LFS, since mesh assets tend to be very large, but I don't really want to blanket enable LFS for every *.asset file.

Thanks!

 

Hi! glad it works

I think the extension needs to stay the same for Unity to reload it. See supported extensions in CreateAsset: https://docs.unity3d.com/ScriptReference/AssetDatabase.CreateAsset.html

Maybe a possible solution could be to add to the extension/filename? e.g. foo.mesh.asset
Or specifying git lfs to track particular files/folders in this case instead of by extension.