Texture compression and mipmaps


OS X: 10.4.2
Renderer: NVIDIA GeForce2 MX OpenGL Engine
Version: 1.1 NVIDIA-1.4.6
API: Carbon

What I’m trying to do is get the driver to compress my original uncompressed texture data using the GL_ARB_texture_compression extension. Problems I’ve found at the moment are…

  1. If I try and use this extension along with GL_SGIS_generate_mipmap, it fails completely (as in it does not compress at all) on my Mac but works fine on the GF2 on my Windows box, I presume this should be valid for the card to hardware generate mipmaps?
  2. If I disable the automipmap and use gluBuild2DMipmaps, it works but one (or more) of the mip levels are corrupted and just has purple stripes running along it, not sure how/why this is happening possible bug again?
  3. I tried just using the base compressed texture and used GL_LINEAR for no mipmaps and the image came out fine, so compression does work on it’s own it seems, but not with mipmaps. Without mipmapping the textures shimmer too much so it’s not really a great option to use.

Both aglGetError and glGetError are checked and seem to not complain apart from problem 1 which just causes a texture not to be compressed anyway. Anyone got any more information on why mipmaps don’t seem to work, is this a known problem with compression?

This is, again, either a bug or an unimplemented feature in Apple’s bugware.

<<flamebait removed>>

“Advanced” features like this are slow in getting implemented (if they ever do) or debugged.

BTW, if you absolutely must use a mac for whatever reason, why are you using Carbon??

I think you’re being a little harsh, but I agree there are a few stupid problems I’ve seen in other areas in their drivers.

I’ve had a deeper look at the 2nd problem and the corruption seems to only effect certain textures as you can see in this pic


So I’ll have to see if I can narrow down why this is happening.

The reason I went with Carbon was because this app/engine is cross-platform and I didn’t really have the time to work out the nuances of Cocoa/Objective-C so played safe with the C style API.

Sounds like yet another bug. File yet another bug report :rolleyes: http://bugreport.apple.com/

At least it’s not as bad as the situation with ARB_texture_compression + SGIS_generate_mipmap on the GeForce 6800, which outright crashes :wink:

Oh, and don’t trust Apple’s gluBuild2DMipmaps, it likes to overrun array bounds for non-power-of-two images in formats other than RGBA/UNSIGNED_BYTE.


I also have some troubles using SGIS_generate_mipmap / ARB_texture_compression with cube map textures…

I am runing on a power book 12’’ so it’s a Geforce FX5200 Go
It’s a bug in apple’s drivers…

Ok thanks all for the feedback, I’ll file a report with Apple, was going to do it quickly but it seems you need to add specific machine exported info, so I’ll have to follow the steps to get that data out.

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