Smoothing groups fbx import bug

My team keeps getting:

“Warning No smoothing group information was found in this FBX scene. Please make sure to enable the ‘Export Smoothing Groups’ option in the FBX Exporter plug-in before exporting the file. Even for tools that don’t support smoothing groups, the FBX Exporter will generate appropriate smoothing data at export-time so that correct vertex normals can be inferred while importing.”

However, we’re exporting the smoothing groups correctly from 3ds Max and we’ve verified the smoothing groups are importing correctly by importing 2 versions (1 with and 1 without).

Seems like people have been having this issue for a while now, so is there anyway Epic could take a look into this?

Hey Cirralisis,

Just to be clear, you’re exporting with smoothing groups disabled, but when you import, the smoothing groups still appear to work on import (even with the error)?

I’m having some trouble reproducing this on my end. Could you perhaps provide your max file?

Hey ,
Not quite. Our test here was with 2 fbx files. One exported with smoothing groups, one without. So, clearly the smoothing groups are being “found” and imported correctly… just wondering if you’re planning on removing this false warning?

That’s the issue though, they SHOULDN’T be found and imported correctly with “Export Smoothing Groups” disabled. I’m trying to figure out if this is an issue with the fbx exporter or with the engine.

What version of Max are you using? Which FBX version are you using as well?

So we’re using the 2014 version of Max with FBX 2014 binary assets.

But let me rephrase, because there’s still confusion:
We created 2 FBX files in Max. With_Smoothing_Groups.fbx and Without_Smoothing_Groups.fbx. We only selected “Export Smoothing Groups” in “With_Smoothing_Groups”

Then we imported both into Unreal.

Without_Smoothing_Groups gave us the error, and as you can see in the image, there are no smoothing groups.

With_Smoothing_Groups also gave us the error, but then it’s still obvious that it was found and applied by looking at the mesh.

So the issue is that we’re getting the error message even though the smoothing groups were imported correctly.

You can pick any random tutorial off youtube and see this bug replicated when they try to import any mesh.

Well, looks like the Answerhub ate my comment on this thread.

Anyways, thanks for the clarification. Now that I have a better grasp on the issue, I’ve been unable to reproduce it on my end when exporting with smoothing groups enabled. I’ve tried with 3dsMax 2014, 2015, and 2016.

Can you send me your fbx and max files, by chance? You can attach here in a zip file or PM me a download link on the forums.

The test files

The Max file

Well, I definitely get it with your fbx files, but I cannot reproduce this when I manually export from your max scene with 3ds Max 2014 (which is what I need to be able to do to enter a bug report).

Can you take screenshots of your entire export and import settings from Max and Unreal, respectively? Please make sure to expand all fields.

Hi Cirralisis,

You get this warning when exporting with “Split per-vertex Normals”:

Reading it, it shows that with “Split per-vertex Normals” enabled, “Hard edges and smoothing groups are also lost”. Please disable “Split per-vertex Normals” if you want to export smoothing groups.

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