The big annoying texture bug

I found this posted 1 half year ago in these forums:

Hello,

When are you going to fix the longstanding Alpha bug, when items with alpha textures half disapear against other items with alpha texture?

Kelly Linden answered the question:

A fix for this is not currently in the development pipeline, although that doesn't mean it won't happen. Our development pipeline changes frequently, and there are many side projects that get completed without being on the official timeline. that said, it is not a trivial problem to fix.

The bug you are refering to is the infamous alpha sorting bug, and believe it or not it exists in most 3D applications and games. You don't see it most of the time because the artists and level designers take great care to avoid it. The following page has a small section about this problem at the bottom. It also has some other good modeling advice.

http://secondlife.com/badgeo/wakka....ealtimeModeling




I have spent a serious amount of time creating a cabinet model, I am planning to create many of them by using this same model. It looks great like it is now. I am using 1 alpha texture because I need some transparent windows, a normal thing.

However after doing some decent research and testing I noticed that this alpha texture is responsible for conflicts with other prim textures that are close to the alpha texture.

Yes it has to be this way, no I can't change the design or make parts stick out more etc....

SL = Build whatever you want!

I have spoken about this problem with other builders, helpers etc.... All of them said it's a SL related bug. I filed a bug report (tons of people must have done this).

In my case the textures show up fine if I use 1024 x .... sized ones.
However this makes the textures look blurry.
But when I use 512 x .... sized ones they don't show up because of the conflict with the alpha texture or they start flickering, this depends from what angle you look at them.

When I move them away from the alpha texture they are showing up just fine.

Now is there anybody who knows how to resolve this?

For example is there a way to create a texture in photoshop with transparant holes in it that function as windows without using alpha channels?

For example by changing the fill % to 98% on the parts of the image that need to be transparant? Is there some trick around this so I can accomplish a glass or windows effect without the use of alpha channels?

Is this bug going to be fixed in the next update? Anybody used the first look viewer to test this?


All help is welcome to fix this problem!

Thank you.

Count Burks

Like Kelly said, this is a problem that's not unique to SL. There's a reason for that: the theoretically "perfect" solution to this problem is so inefficient to implement that no computer can handle the computation it would require. SL would run much, much slower.

That said, apparently in the new version that's due out soon, there are some fixes to alleviate this problem (but not fix it entirely). Maybe that'll help with your cabinet.

The thing is, there really is no good solution for this. Any texture that has any alpha in it or has the transparency slider set to anything above 0 in the Texture window will potentially have layering problems with other alpha textures. The best thing you can do is try to build in such a way as to mask the effects of the bug. To answer your question, unfortunately there isn't any kind of workaround like you described.

You can find this problem in games as well. Most games, since their content is static have been optimized and instructions put in to make sure the textures layer properly. However, some games still have dynamic content that has alpha textures. The biggest is grass in many MMOs. If you stand just below the crest of a hill and look through the grass, you'll see that it behaves just like alpha textures and transparencies do in SL. It's just more noticeable in SL since everything is dynamic.

Thanks for the info, the weird thing is that when I use large sized textures 1024 x ..... in combination with the alpha channel layer those textures load fine without flickering or dissapearing but they look a bit blurry. I will see what happens with the next update and keep this in mind when I create the layouts for the new cabinets.

Thanks for the information.

Count Burks

I'm not sure why the resolution of the texture would help, but please, spare our framerates. Changing all of your alpha textures to 1024 is definitely not a good solution ;)

If you only have one alpha texture in the object you shoudl not get any alpha sorting problems. It sounds like some of the other textures that you're using are alpha (32-bit) textures, even though they don't actually have any transparent sections in the alpha channel. Try re-uploading the textures as BMP instead of TGA to make sure they're 24-bit non-alpha textures and not 32-bit alpha textures in drag. I've had to do this several times, including downloading and re-uploading a couple of textures I'd bought!