Why do my walls keep disappearing?

I have been building in SL for over a year now, but have experienced a problem with my builds, especially my larger scale ones, that I suspect is the result of newbie-like ignorance on my part.

When viewed at from certain angles, walls, floors, or even particular sides of smaller objects will simply vanish. When I shift my camera perspective, they reappear again. The result is that, from some angles, entire portions of my buildings will appear to be not there. It's not as though the entire prim disappears: just one particular facet of it.

At first I thought the problem was with my rather old computer, but I have a new machine now, and the issue seems if anything worse.

I am beginning to think that the problem may be with the textures that I have made for these. I use pretty much exclusively PNG textures. Might there be a problem with the way that I am saving them in Photoshop?

Any help that anyone can provide with this would be much appreciated.

a couple of threads that might point you in the right direction for your answer:


/111/79/334820/1.html

/8/d8/325619/1.html

It's alpha sorting. Read the sticky thread on Alpha textures and transparency at the top of the Texture Tips forum. It is very easy to accidentally save a PNG texture as a 32-bit image. Even if you do not have any intentional transparency in it, the extra 8 bits will cause a potential sorting problem.

Thank you both very much for this. I'll check out the threads that you suggest.

I had an uneasy feeling that it was the textures likely causing the problem. Sadly, it looks as though I will soon need to be re-importing and re-applying hundreds of textures as a result. Such is the cost, I suppose, of not adequately researching these things before leaping right in.

Again, thanks.

If your textures do NOT contain an alpha channel, the problem might be the current viewer. It makes about 50% of the prims disappear of a cave that I've built over 2 years ago.

You might want to double-check your build with an alternative viewer like the Green Life Emerald viewer. Using the Emerald viewer fixed the problem for me.

Quite simply, stop uploading PNGs as they have an alpha channel built in. JPG or BMP only for non-alpha textures or they'll clash.

No, that's not true. PNG images can be 24-bit, just as TGA images can. The big difference is that PNG files can contain a few pixels that have 8 extra unnecessary bits, even if you didn't plan any transparent areas at all. If you save an image that has even a single 32-bit pixel in it, the whole thing gets saved as 32 bits. The way to avoid it (in Photoshop) is to use the "Save for Web" option that forces the file to save as 24 bits. If a PNG file is truly a 24-bit image, there's no way you will have a sorting problem.

Read the sticky thread on Transparency and Alpha channels at the top of the Texture Tips forum for a longer and much better desciption than this short one.