Normal Maps with mirrored UV's again...

Accipiter · Nov 2013

I hate to bring this subject up because I think I've read every post about this problem...but for some reason I can't solve my issue.

Normal Maps with mirrored UV's in UDK.

This object is a Static Mesh, just for a test, it will unfortunately need to be a Skeletal later. But lets not worry about that at the moment.

I've read through the posts:
http://www.polycount.com/forum/showthread.php?t=116922
(haven't done the Material trick, which might be my only solution at this point)

http://www.polycount.com/forum/showthread.php?t=108243

Here is my example:

http://www.rhinton.com/images/Polycount/Monitor_01.jpg

And here are my Max FBX export settings and my Unreal Import settings, what am I missing?

http://www.rhinton.com/images/Polycount/Monitor_02.jpg

Fingus · Nov 2013

Well like we concluded in my thread, turning off Explicit Normals will fix it. As far as I understand the problem is with Autodesk's FBX exporter that doesn't handle flipped UV's correctly, or at least differently from what UDK expects.

However if you need it for a character I guess you'd have to do the material hack I came up with.

r4ptur3 · Nov 2013

on export, export tangents and binormals. on import, uncheck import tangents (keep explicit normals turned on). I know this sounds counter intuitive, but it usually works for me.

Accipiter · Nov 2013

Yes, does seem counter intuitive and here is my result. Really don't understand the problem.
It's only a normals thing, as when you pull off the normal map everything is fine.
Picture on the right shows the normal into the diffuse channel, no seam.

r4ptur3 · Nov 2013

is your green channel flipped by chance?

ZacD · Nov 2013

Don't you need to offset the UVs for the mirror half?

Accipiter · Nov 2013

If by offset you mean Fingus' technique then I'll have to do that. Haven't tried it yet because I was trying for other solutions that were figured out by what r4ptur3 had stated.
Doesn't seem to work for me however.
I'll also try flipping the green. (forgot to do that)

Monster and Fingus had talked about it being something to do with the FBX exporter. So I'm on that end with some UDK folks to figure that out too.

A real pain for sure.

Accipiter · Nov 2013

So basically to close this thread with solid information, and after a couple of days BSing around trying to get things to function, just don't do this.

The quote I got from some UDK people, "You will just have to work around the flipped UVs issue. We as a rule avoid doing this and usually end up with our maps non-overlapping for mirrored parts."

So if you try and conserve space, but you want to add a Normal Map to your object, you'll have to perform Fingus' solution, especially if you're working with Skeletal Meshs.

Unfortunately I couldn't get this to work when I tested it as a Static Mesh.
I tried and on export, export tangents and binormals. Then on import, uncheck import tangents (keep explicit normals turned on).

I think in the future I'll just lay everything out flat without Mirroring.

Fingus · Nov 2013

I haven't tested this in a while, but I'm pretty sure that it's the Explicit normals you need to have turned off.

Accipiter · Nov 2013

I ended up trying it that way too. Still couldn't get the result I needed.

Obscura · Nov 2013

I also wasnt ever been able to fix this issue. I tried out the offset, different import settings, placing my symmetry axis to a flat surface, but nothing helped.

edit:

But...I dont know yet if it can be related to a similar thing as the rotation/lighting issue with the modular pieces in UDK, but if yes, then maybe this can help:
http://www.polycount.com/forum/showpost.php?p=1867453&postcount=2

Just ignore this, if its bullshit

Havent tried it out.

Normal Maps with mirrored UV's again...

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