CGTalk - Weird artifacts when using .tga transparency on texture.

bluedragon128

07-18-2003, 05:09 PM

I've had this happen to me back in 4.5. When I was building my character certain areas looked as if backface culling was on. This has been since December and if I remember right it was some normals got flipped around. Or it because the texture file I applied to my model had an alpha channel. If I could only find my old model I could tell you exactly what it was. Hope that helps.

GRMac13

07-18-2003, 07:10 PM

Dammit, this really sucks. I need to show a potential employer a screenshot of the textured model. I can't just show him a render because it's for a game, so he wants to see it with hardware texturing. This looks so ugly, there's no way I can show it like this. I guess the only option is turn off the transparency and explain that it's a maya issue that won't transfer into the game engine.

Thanx anyway, guys.

Levitateme

07-18-2003, 08:02 PM

you could just use another texture type? that would solve everything

GRMac13

07-18-2003, 08:05 PM

Originally posted by Levitateme
you could just use another texture type? that would solve everything

What do you mean? I tried using .tifs and even .jpegs with the same result. It seems I just can't view combined textures in the viewports for some reason.

Levitateme

07-18-2003, 08:14 PM

hmmm. wel maybe i am thinking of soemthign else than. can you post a pic of what its doing. and what do you mean by

It seems I just can't view combined textures in the viewports for some reason.

that came out of nowhere, of course you can view more then 1 texture in your viewport.

GRMac13

07-18-2003, 08:30 PM

Originally posted by Levitateme
that came out of nowhere, of course you can view more then 1 texture in your viewport.

I know, but I can't view them correctly is what I am saying. See where is says "textured channel." I am able to view the color channel fine, and if i select "transparency" I can even view the transparency channel (though nothing is transparent, it just shows the B&W alpha on the model). If I tried to view both the color and transparency channels (by choosing "combined textures") that's when I have the issue with the model looking all corrupted.

Levitateme

07-18-2003, 08:34 PM

hi GR< that sounds like a video card problem then. cause i have a ...oi... i dont even remember but its not very old nvida card but it works fine for me. that pic you attached taht isnt showing what the model is doing though. just your settings . you can email me your scene with the 2 textures your using, i can take a look at it if you like.

GRMac13

07-18-2003, 09:18 PM

Originally posted by Levitateme
you can email me your scene with the 2 textures your using, i can take a look at it if you like.

I'd love to, but I'm under a sort of non-formal NDA with this company. So I can't really show the model, and I definitely can't send out the file. Maybe I'll just make a new scene with a simple object and send that.

Thanx for the help.

Levitateme

07-18-2003, 09:42 PM

sure

bluedragon128

07-18-2003, 11:02 PM

Let me get this right, you are using the same file texture for both the alpha and the color information? Have you tried making two seperate files for alpha and one for color? If you are using one file for both alpha and color it will look funky. Make sure that you delete the alpha channels in photoshop before saying, that should prevent them from conflicting, and should give you the results you want in Maya.

johs

07-20-2003, 06:13 PM

I have that problem too, and it's a pain in the arse.

But i don't think it's a transperency problem. I have seen it when i'm using a procedural texture (checker, with no transperency), and i change the "Hardware Texturing Resolution" on the shader, to anything else than "default" (if i change it back to default, there is no problem).
But it also seems to only be a problem inside maya's wievport, there are no problems when it renders.
And i have seen it both on Nvidia cards and Wildcat cards, so don't think its driver problem, but rather a bug in maya or some sort of OpenGL problem.

Anybody know of a bugfix?

Atwooki

07-20-2003, 09:22 PM

Johs:

Same thing over here

NIGHTMARES!!!

Atwooki

Electrofirma

07-21-2003, 07:58 PM

I believe it is the gfx card.

I've got two setups... One with a GeForce 2 and one with a Radeon.

The GeForce has the problem, and the Radeon is fine.

I honestly believe this is a 'feature' nVidia has allowed to remain in their consumer level cards, to help drive sales of their highend workstation cards.

GRMac13

07-21-2003, 08:03 PM

Originally posted by Electrofirma
I believe it is the gfx card.

I've got two setups... One with a GeForce 2 and one with a Radeon.

The GeForce has the problem, and the Radeon is fine.

Well I have two PC's as well, both with different model GeForce cards, and I get the same issue on both.

This makes me wonder though...for those who have encountered this problem, what brand of vid card are you all using?

For the record, my main PC uses a GeForce 4 Ti4600.

My second system just has an older GeForce 3.

johs

07-21-2003, 08:11 PM

I have seen it both with a Gforce2 and with the 3D labs Wildcat II 5110

Electrofirma

07-21-2003, 08:11 PM

My GeForce is an old GF 2 MX 400, yet I have seen it on GF2-4... the Radeon is their Mobility laptop chip.

As I edited earlier... I believe this is a flaw, that has been allowed to remain in the nVidia consumer level cards, to add value to their workstation chipsets.

I could be way off base though.

Electrofirma

07-21-2003, 08:24 PM

From AliasWavefront... ( http://www.alias.com/eng/support/maya/qualified_hardware/QUAL/maya_50_win.html#cards )

nVidia GeForce256, GeForce2, GeForce3, GeForce4 series

There are many cards based on GeForce256, GeForce2, GeForce3 and GeForce4 chipsets. nVidia and Alias|Wavefront do not recommend these cards for use with Maya as you may experience various refresh, display and stability problems and inadequate performance.
We suggest you choose from nVidia's workstation cards instead, such as the Quadro families which are much better suited to high-end 3D packages such as Maya.

3Dlabs Wildcat II 5110

Model Version Driver Settings ON OFF
3Dlabs Wildcat II 5110 (3Dlabs) Windows XP Pro:
06.05.05.16 Settings > Performance
Driver Setting: Maya x
Limitations and Solutions
Limitation Hardware shadows, CubicReflections and Hardware Rendering not supported. This card is not recommended for use with Hardware Rendering as not all features are supported.
Solution None

Good info at the page I linked above.

gmask

07-21-2003, 08:24 PM

Here's the answer..

In order to use an embedded alpha chanel as transparency you will have to invert the alpha. You can either do this in Photoshop or by inserting an reverse utility node and the connection editor.

If you use the latter method your OpenGL display will still use the alpha correctly for hardware textur edisplay.

Or you can save the alpha as a seperate image file and assign it to transparency.

For whatever reason white is transparent in maya whereas in ost other programs black is transparent.

Electrofirma

07-21-2003, 08:35 PM

Here's the answer..

No! what they are speaking of is a different issue than simply opacity vs. transparency. It is a zbuffer miscalculation that appears in the workspace viewports, but not in the finished renders.

Objects affected by this appear proper in their transparency, but they are depth sorted wrong. In fact what makes it excedingly goofy is that, in the case of hair, you will see hair from the otherside of the head as if both the front faces, and the head, were gone. Also strange is that the back faces will shine through, but only where their is a front face. It is as if the object gets boofed without any regard for the surrounding scene.

Electrofirma

07-21-2003, 08:49 PM

Here's a quick shot to help illustrate the issue... this is really a minor case here. Wouldn't you know that I'm having trouble finding a real messed up one :)

Electrofirma

07-22-2003, 12:45 AM

BTW... I fought through replacing vid drivers and setting up SoftQuadro as outlined in this thread... http://www.cgtalk.com/showthread.php?s=&threadid=17331&highlight=slowdown

I don't think I had the slowdown problem the thread mentions, but I thought having the card recognized as a Quadro might help this issue... But alas, it was not meant to be.

This issue is still going to be the driving force behind my next gfx card upgrade.

GRMac13

07-22-2003, 12:58 AM

Originally posted by Electrofirma
No! what they are speaking of is a different issue than simply opacity vs. transparency. It is a zbuffer miscalculation that appears in the workspace viewports, but not in the finished renders.

Objects affected by this appear proper in their transparency, but they are depth sorted wrong. In fact what makes it excedingly goofy is that, in the case of hair, you will see hair from the otherside of the head as if both the front faces, and the head, were gone. Also strange is that the back faces will shine through, but only where their is a front face. It is as if the object gets boofed without any regard for the surrounding scene.

Thanx Electrofirma, you articulated the issue much better than I could have.

In terms of vid cards, I am running SoftQuad on my GeForce 4, and I still encountered the problem.

Bah, I've been thinking of upgrading soon anyway. Although, I assume the issue would still be present with a GeForce FX card. I may just break down and get the Quaddro.

Still, I want to hear from people who have this problem and are NOT using a GeForce card.

Electrofirma

07-22-2003, 09:52 AM

Just as a final note... After going through and replacing drivers and setting up SoftQaudro I started getting other issues in Maya.

I got image tearing (Horizontal flicker) when panning views, and improper redraws when displaying menus.

Anyhow, I've reverted back to previous setup, and all is good. I usually don't get off that cleanly. Under normal circumstances on my system, fiddling with third part video driver utilities, causes the system to spontaneously reinstall.

I'll be looking at the Radeons next time I think.

johs

07-22-2003, 12:40 PM

This is what it looks like on my Wildcat card, so I don't think it's Nvidia specific problem, I think its a bug in maya.

Normal (http://johannessebastianjoergenerikmoegelvang.dk/ost/ZsortNormal.avi) Wrong (http://johannessebastianjoergenerikmoegelvang.dk/ost/ZsortWrong.avi)

Its a brand new lambert shader with a brand new checker procedural tekture on, and there are no sorts of transparency involved.
The problem ocures when I change the Hardware Texturing to anything else than default

http://johannessebastianjoergenerikmoegelvang.dk/ost/ae.jpg

And yes, I know that wildcat cards have problems with many of the more advanced Hardware rendering fearures, but this should not be one of them. This is planley texturing.

GRMac13

07-22-2003, 12:46 PM

That's exactly the problem I have (except so far only with transparencies). Also, I have the problem no matter what I set my Hardware texturing to, default or otherwise.

That's really weird. The only thing that throws me off is that if this is just a bug in Maya, why aren't more people experiencing it?

Do you get the problem with transparencies too? That's the only time I get thateffect is when I'm trying to view transparencies, so it's strange that in your case it happens regardless.

Electrofirma

07-22-2003, 05:19 PM

johs,

Yeah, that certainly acts the same, but my problem on the gForce is directly related to transparencies.

I don't think it is a bug in Maya or we would have alot more people in here complaining. I think it is a bug in the graphics cards implementations of OpenGL.

I did an animated gif of a thing that shows it without transparency, and again with transparency set to .001.

gmask

07-22-2003, 06:15 PM

Originally posted by Electrofirma
Here's a quick shot to help illustrate the issue... this is really a minor case here. Wouldn't you know that I'm having trouble finding a real messed up one :)

Oh in that case I would say you can't depend on your OpenGL display . I there is only card that is approved for the recent hardware rendering.. otherwise everycard is going to behave differently.