Multiple UV Channels in Max 2008...

Dakkon

Hey guys.. So I'm trying to apply a 2nd and 3rd uv channel to an object in Max. I do a UV Map modifier, select channel 2, and apply it. I go into the Unwrap, and it's using the same UVs as channel 1... I've tried applying it in different ways, and nothing works. One thing I have noticed is that in the past when I've used the UV Unwrap modifier, it gives me a little warning every time I switch between channels. That warning isn't there anymore... Any ideas?

Dakkon

Ah, just checked Max 9, and it works... so I think I might have hit a setting somewhere that screws this up in the Unwrap UVW modifier. No clue where that might be though

MoP

I think by default it will just use Channel 1's UVs if Channel 2 doesn't have any UVs already assigned?
Try doing something like adding a UVW Map modifier (plane/box/whatever) and make sure it's set to channel 2, then add an Unwrap UVW and see if that makes any difference in channel 2.

Dakkon

It's a little weird.. I have this shader up that uses channels 1 and 2. If I UV Map on channel 2, it shows up working fine in my shader. If I try to unwrap, and go to channel 2, it resets the UVs back to use channel 1... it's very odd.

Joshua Stubbles

Strange. I don't have that issue at all in 2008.

Mark Dygert

1st use UVW Unwrap, it does almost everything that UVW Map does, with the exception of one option which game artists rarely use.

2nd If you're switching back and forth between 1 and 2 it sounds like its resetting to default which is the last "baked" layout. So either be prepared to do a lot of loading/saving each time you switch (by changing the channel) or instead use two UVW unwrap modifiers. One set to channel 1 and the other set to channel 2. Toggle on and off the visibility of the upper most (click the light bulb in the history stack) normally 2, when you need to work on the bottom.

You can edit channel info (delete any unnecessary channels) by going to Edit > Channel Info. Know that every object has a few channels to start with so not everything is useless. Extra UV map channels will show up as #:map. The following are normal and shouldn't be removed: mesh, vsel, -2:Alpha, -1:Illum, 0:vc.

Dakkon

Yeah, I'm using a mix of UV Map and UVW Unwrap. It's the UVW Unwrap that's screwing up somewhere. And you're right, it seems like it's resetting the uv channel back to channel 1 for everything when I'm cycling though.

Snight

Every time you change your Map Channel you must press the "Reset UVWs button". A prompt will appear asking if you're sure you want to reset, press Yes. Now go into your UV Editor it should display the Map Channel you chose. Hope that helps you.

Note: Make sure you collapse your stack first or add another edit poly and unwrap before doing this. Otherwise you will overwrite your UVs.

Jesse Moody

Yeah I was gonna say make sure you collapse your stack every now and then to "save" your uvs on that channel


I have to do this for light maps for ue3 so I will do all my unwrapping on channel 1 for my diffuse, spec, normal, etc and then once done collapse.

I get my textures fully painted and complete and before exporting I will work on my second uv set for the light map and once that is complete I will collapse the stack and then save and export.

Ryno

It'll always display UVs for channel 1 unless you hit the edit button, and in the Edit UVs dialog box, choose File > Reset UVs, to show any other channel.

jbrophy

This is a horrible Bug(Update) that autodesk added to max.

http://area.autodesk.com/index.php/forums/viewthread/1110

Joshua Stubbles

You know for the life of me, I can't get different UV channels to display in the viewport at all. If I'm working on channel 3, I have to change it to channel 1 in order to see it. That in turn, makes the UV edits apply to channel 1....
Not sure if that's exactly related to the above issue, but it's beyond frustrating.

Ruz

why why why did they do this. what a gigantic pain in the ass

Joshua Stubbles

I understand resetting of the UVs - that doesn't bother me so much anymore. Instead of asking now, it auto-copies UV channel 1 into the new channel, as a starting point (without asking). Once you layout the chan3 UVs and collapse the stack, it's easy to edit them again. You just apply the unwrap, hit chan3, hit ResetUVW's, hit "yes" then "edit" and you're good to go.

What's burning me now, is that I cannot farkin SEE my UV channel 3 edits in the viewport. How the hell am I supposed to know the texel density if I can't see my damn texture! GRRRrr

Ruz

Vassago, can't you just change the id in the material editor to channel 3?

Mark Dygert

[ QUOTE ]
What's burning me now, is that I cannot farkin SEE my UV channel 3 edits in the viewport. How the hell am I supposed to know the texel density if I can't see my damn texture! GRRRrr

[/ QUOTE ]
Thats because your diffuse map material is set to use channel 1.

You could copy your material to a new slot, and change the Map Channel to 3, then just assign that material when you want to view Channel 3. It wouldn't be too hard to write a script that does that for you, then you can bind that to a key stroke or a button.

Joshua Stubbles

Well I'm a moron, so leave me alone
Damn, I could have sworn I saw them work in the viewport (on a single material) in the past.
That's what I get for being out of art for 2 years.
Thx Vig, Ruz

Eric Chadwick

Wow, this Unwrap change makes me glad we stayed with Max 9. I guess it would make sense though if the UV channel you were changing to didn't have UV data yet (copying #1 in would make sense then), but if it already has data? Ouch.

Joshua Stubbles

It doesn't erase the UVs though, Eric. It wipes the slate clean, yes, but not permanently. All you have to do is hit "reset UVs" and you have your UV's back.

So if you go to map chan3, it will auto-copy the chan1 UV's into it. You can then hit 'reset' if you want it to default to a generic planar map. From there you just map as you normally would. Once you collapse the stack, you can still access everything just fine. If you apply a UVW UNwrap and channel 1 is selected, if you hit channel 3 it will re-copy channel 1 UV's again. But then you hit "reset uvws" and it will bring back the UV's you made earlier. So while it temporarily erases the UV's, they're not really gone.
Though if a person didn't know about the issue (as most of us do not) it would seem like a HUGE bug.

Eric Chadwick

No, I understood the reset functionality, I just don't agree with the way it works. It only makes sense to auto-copy UV1 if the channel you're changing to doesn't have any data yet. Otherwise it's just a stupid design choice.

Joshua Stubbles

I agree, it wasn't a smart thing to do.

Mark Dygert

Another backwards feature of the UVW GUI is that it doesn't allow you to remove UV channels. You either need to use the "UWV Mapping Clear" modifier.
Or go to Edit > Edit Channel Info find the channel and "clear it" which does the same thing. To me it makes sense to have that in the modifiers GUI and not handle it with another modifier but, meh, semantics...