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3D Texture Problem with Linux

Started by Ben_C Jan 7, 2003 at 8:56 PM 2 replies 550+ views

Original Post

Jan 7, 2003 at 8:56 PM

I''ve been working on a volume rendering application that uses large 3D textures with NVidia hardware. I''m currently testing it with a GeForce 4600 with 128 MB. I was unable to load a 3D texture larger than 64 MB in Windows, and no larger than 32 MB in Linux (textures have been 512x512x128 x 1 byte or 512x512x128 x 2 bytes). OpenGL did not return any errors, but anything rendered with the texture showed up as solid black. Oddly enough, I haven''t been able to find information on texture size limits on the 4600. But mainly, I''m curious why a 64 MB texture would work in Windows but not in Linux. I realize that''s a bit vague, but I''m wondering if anyone has heard of any similar problems. Thanks!

JonnyQuest

Jan 8, 2003 at 11:07 AM

Even if you're using OpenGL, run the DirectX Caps Viewer program and inspect your hardware's texture extent limits, it might be insightful.

EDIT (more ideas): Unless your card has 256MB video memory (does the NV25 support that?) it's not surprising that you can't load textures larger than 64MB. The next step (thanks to POW2 restrictions) would be 128MB, which would fill the VRAM beginning-to-end, leaving no space for the frame buffer, etc.
An idea as to why Linux doesn't want the big texture: maybe the VRAM is fragmented, and there's no single 64MB block unallocated? What's your framebuffer size, what kind of depth surface are you using? Are you allocating anything else as well?

- JQ
Full Speed Games. Are back.

[edited by - JonnyQuest on January 8, 2003 12:11:12 PM]

Ben_C

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Ben_C

Jan 8, 2003 at 11:47 PM

Thanks for the response.

I didn''t know whether textures were compressed on the card, allowing larger sizes than 64 MB.

The only other texture I''m using is 256x256x4, almost nothing. Texturing works fine at 1600x1200 resolution in Windows, so the frame buffer size probably isn''t the problem. I hadn''t considered fragmentation in the VRAM though. Probably need to try running a few more tests.

And sorry I didn''t post this in the GL forum

Yann L

219

Yann L

Jan 9, 2003 at 6:13 AM

You should check out the NV_texture_compression_vtc extension. It allows a s3tc-alike compression for 3D textures.

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