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Potatopopper 03-09-2005 05:40 AM

OpenGL screensaver screen tearing
 
Hi, I am using

kde 3.3.0
slackware 10.1
Xorg 6.8.2 with latest radeon snapshot for radeon 7500
kernel 2.4.29

and when I have an opengl screensaver displaying, I see tearing all over the screen. I'm thinking maybe there is an option for vsync that I can append to the xorg.conf? I'd really like to know why this is happening, so if anyone knows how to stop this, please let me know :).

Thanks for your time.

Seppel 03-24-2005 12:01 PM

Hi Potatopopper,

if you're using XScreensaver (especially 4.19), please try a search around this forum about your problem.

It might be related to your graphics drivers (I've heard that the ATI support for Linux is a mess). If that's the issue, I think you have to wait until ATI (or somebody else) releases working drivers for your Video Card.

Greetings,

Seppel

wrb 05-05-2007 07:51 PM

Screensaver screen tearing
 
It's been my experience that tearing is usually the result of drawing during screen refresh. If the window is double-buffered, the buffers are being swapped in the middle of a (video) refresh. This was happening when I was using the "really slick screensavers" code ported to OpenGL by Tugrul Galatali (with many thanks, BTW). So I defined GLX_GLEXT_PROTOTYPES, included <GL/glxext.h>, and a call to "glXSwapIntervalSGI(1);" at the bottom of the createWindow() function. This ensured only a single "swapbuffer" can occur per video refresh. Drawing faster than the video refresh rate generally yields diminishing returns (visually & computationally). If your screen refresh rate is 60hz, calling glXSwapIntervalSGI(2) will yield 30 fps, (4) for 15 fps, etc.

Hope that helps,

=>Bill


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