Max to FBX export - Multiple UV Channels?

leechdemon

I'm exporting some files through FBX to be used in our engine, and we're noticing that the UV channels are being written to the FBX file incorrectly. Basically, what's happening is that our importer is taking the first UV channel listed and assigning it to UV1, second one listed as UV2, etc. When realistically, with 2 UV channels, it's listing UV2, UV1, and UV0 (in that order). They're all being NAMED correctly (UV1 is in the second "layer element", but is correctly named "UV Channel 1"), they're just ordered incorrectly.

While stranger behavior, I'm arguing that our importer should know the difference. Is that correct? Or is something going on wrong in my Exporter? (Max 2010, FBX 2011.3.1). Is it commonplace to look to the channel's NAME rather than it's location or layer ID?

Butthair

I'm not sure which it is, but I can qualify that I've exported .FBX files with multiple UV channels to UDK and it imports with the correct number of UV channels (in this case I've exported Channel 1 and 2 and they show up as 0 and 1 in UDk). They also are ordered correctly.

I run Max 2011 with FBX 2011.3.1. The FBX exporter use to give me problems too though, but by randomly adjusting some settings I've gotten it to export without error. You may need to test several settings...

leechdemon

Well, I've basically narrowed it down to "something with the exporter". If you export to FBX as ASCII, and open it up in a text editor, THAT'S where I'm reading that they're coming up "wrong". I know our importer assumes they're channels 0 and 1 (hence our issue), what I don't know is whether or not UDK, for example, does the same. Or, is UDK going "well, I'll take what they CALL "UV Channel 1" and assign that to UV1, rather than simply the first thing listed".

Glad to hear it's at least the same FBX version. I'm assuming UDK and others go by name and not by order (because "order listed" seems entirely arbitrary, imo...), but I'm just trying to check. Thanks for the info!