Display errors using glDrawPixels with driver 6629

[blond]

Hi all!

I updated to driver version 6629 and now a get some strange display errors with my app that is using glDrawPixels(). Others like glxgears run fine. As I am a GL beginner, I don't want to blame the driver, maybe it's just me doing something bad...

To track down the problem, a small example is attached that simply shows a pattern in a loop (sorry, bad code, but it's just an example :-) ). But instead of a still image, I get some flickering, although the example uses DoubleBuffering. If I start a second instance of the example, the flickering is getting worse, so they seem to interfere.

I'm running Debian sid with kernel 2.6.8.1 on a 2GHz Pentium 4. Motherboard is an Asus P4B266-E.

cat /proc/driver/nvidia/cards/0 says:
Model: GeForce2 MX/MX 400
IRQ: 11
Video BIOS: 03.11.01.43.00
Card Type: AGP

I would be verry happy about any help and hints you can give me. Thank you in advance!

[blond]

Hi again,

now I replaced the glDrawPixels() with some polygon drawing stuff, just to verify that the problem is related to glDrawPixels(). And yes, drawing polygons works fine. Is there something special with glDrawPixels()?

blond.

[blond]

Now I'm pretty sure it's a driver problem. After reverting to 6111, the problem was gone.

Additionaly, I realized that the image with 6629 has vertical "stripes", with 6111 it has not. Attached you can find two screenshots, the gl-6111.png shows the correct output of the example program with driver 6111, the other shows the problems. The stripes remain constant, but the block-like structure is changing over time (what I called "flickering" above).

Any suggestions?

[blond]

Found out further details:

The error can be reproduced with other apps, too. Playing around with the drawpix demo from the mesademos, the "blocks" occure if you set PixelZoom to anything else but 1 (eg by pressing y, Y, x or X) and then generating expose events (eg by moving another window around) so the window gets redrawn.

So the problem is related to glPixelZoom(): if set to anything but 1, the blocks show up. If you set winwidth to 640 in my example code, pixelZoom will be 1 and the problem is gone. Set it to 641 and they show up again.

Another strange thing: If I move the window to the left or to the top, partially out of the visible area, the image "moves": a border shows up that is as wide as I move the window off the screen.

May anybody else reproduce this? I would be very happy if someone could try this, please! This would show if the problem is relateted to my installation, the hardware or if it is a general problem.

Thank you!

[macks]

May anybody else reproduce this? I would be very happy if someone could try this, please! This would show if the problem is relateted to my installation, the hardware or if it is a general problem.


In your test app I don't see the flickering artifacts with 6111 but do with 6629.

[blond]

In your test app I don't see the flickering artifacts with 6111 but do with 6629.

Thank you, macks!

Now I'm pretty sure it's not an installation problem, will send a bug report...