nVidia: Bug with s3tc and automatic mipmap generation?

[Jan]

Hi

I stumbled across something, which seems to me like a driver-bug. I could not find anything wrong in my app, so please have a look at it:
http://www.artifactgames.de/FILES/START.PHP?where=BUG.PHP

For all screenshots i used trilinear filtering, but the same happens with all filtering modes.

Jan.

[jwatte]

It's been my experience that letting the driver have anything to do with generating S3TC data is a receipe for disaster:

1) It won't perform well at all
2) It won't look as good as offline generated DDS files

Thus, if you need MIP maps, you should pre-generate them and store them on disk.

Note that auto-generation of MIP maps is only useful for formats that the card can GENERATE natively, which usually means RGB(A)8 and possibly the 5-bit and float versions thereof. S3TC isn't on that list; the CPU will generate the MIP map in that case (if it's generated at all).