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Old 05-16-06, 01:09 PM   #1
jrtimanu
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Join Date: May 2006
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Question GLSL texture coordinate generation broken in ver 8756

Hello All,

While trying to implement manual automatic texture coordinate generation in a GLSL shader with the following code, I've found that the gl_ObjectPlane* and gl_EyePlane* uniforms are not being properly assigned with the values provided by the application.

The following snippet of vertex shader code does not work as expected:

gl_TexCoord[0].s = dot( gl_Vertex, gl_ObjectPlaneS[0] );
gl_TexCoord[0].t = dot( gl_Vertex, gl_ObjectPlaneT[0] );

In the applicaiton I initialize the object plane vectors to be the standard orthogonal basis vectors, but the rendered image implies that a shearing matrix as been applied to my inputs. This behaviour happens regardless of the current state of the model view matrix or the texture matrix.

I first noticed this behaviour when upgrading my drivers to 8756. I've reproed the problem both on a Quadro FX 1100 and a Quadro FX 4000.

The operating system and machine type used to repro this behaviour are as follows:
Linux 2.4.21-27.ELsmp #2 SMP x86_64 GNU/Linux

Has anyone else noticed this behaviour? Is there a workaround? Will it be resolved in the next set of drivers?

Thanks,

Jeff
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Old 05-16-06, 02:21 PM   #2
netllama
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Default Re: GLSL texture coordinate generation broken in ver 8756

Please provide a reproducible test case along with an nvidia-bug-report.log.

Thanks,
Lonni
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Old 05-17-06, 06:23 PM   #3
retinalburn
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Default Re: GLSL texture coordinate generation broken in ver 8756

I am experiencing the same problem here with two of my own applications. One is using texgen for a 3D texture volume renderer, and the other is using texgen for shadow mapping. Using the gl_ObjectPlane with built-in uniforms with a 3D texture gives me sheared texture coordinates. With gl_EyePlane in the shadow mapping app, I'm not sure exactly what the transform is, but the texcoords are definitely wrong.

As a workaround, I switched to using generic uniforms and it works as expected. The built-in uniforms were working up until the 8756 driver. I've seen it on multiple cards: GeForce 6800 GT, GeForce 7900 GT, and Quadro 4400. It also happens with both 32-bit and 64-bit drivers, and I've seen it in RedHat Enterprise WS 3, FC4, and FC5.
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Old 05-18-06, 04:01 PM   #4
tachyon_john
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Default Re: GLSL texture coordinate generation broken in ver 8756

I'm also seeing this same texgen problem with GLSL, and I've also hit some
internal compiler errors on a different shader.

John Stone
johns@megapixel.com
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Old 05-18-06, 04:32 PM   #5
tachyon_john
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Default Re: GLSL texture coordinate generation broken in ver 8756

Hi,
The VMD test dataset I'm using to expose the various bugs in the 8756 drivers is a bit too large for the forum's upload limit (6MB) so I've posted them for you here in both zip/tar.gz formats:
http://www.ks.uiuc.edu/Research/vmd/alpha/test/

Even the nvidia-bug-report.log file is too big for the forum's 100KB limit, perhaps you guys ought to crank up the file size limits..... :-)

John Stone
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Old 10-17-06, 06:03 AM   #6
ocroquette
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Default Re: GLSL texture coordinate generation broken in ver 8756

Hi jrtimanu

I think I have the same problem as you.
How did you solve it out (if you did ) ?
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Old 10-17-06, 06:21 AM   #7
ocroquette
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Default Re: GLSL texture coordinate generation broken in ver 8756

Update: I just installed the 9625 beta drivers, they seem to solve my problem!
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