[visionegg] Re: Motion tearing on PC

Hi Andrew,

I tried our motion stimuli on 2 different PC's
1) OpenGL 2.0  and a Radeon 9550
2) OpenGL 1.5 and a Radeon 9700

and I am happy to report that both systems
showed no tearing and I could draw 4000
anti-aliased points @ 60HZ refresh(1600x1200 resolution).
Fantastic!
Thanks much,

Doug

Andrew Straw wrote:

Hi Doug,

This seems like it's most likely a driver issue.

The first thing to do is to make sure the Vision Egg is actually using
the latest ATI OpenGL drivers. The exact driver information should be
displayed on the console and saved in the log file. If you do have the
latest OpenGL drivers and you still have this problem, I think you have
2 options: 1) install card without such driver issues (e.g. the nVidia
5200 at less than $50) or 2) play around with the new, unannounced
win32_vretrace module to achieve (via your own blood, sweat, and tears)
what the drivers should be doing for you.


Douglas Taylor wrote:



Hi All,

I have a motion stimulus that is made up of dots
that I've tested on a Mac and a PC and it runs fine
on both systems except on the PC it tears. It is synced
with the VBL(both thru Visionegg and the ATI control panel)
and I get back the correct frame rate
so it looks like the PC is blitting from the back to front
buffer during a swap buffers whereas the MAC is
page-flipping. The card in the PC is a AGP Radeon 7000.
Not the fastest of cards but they work fine on the MAC.
I experienced this before on MACS when OS9 came out
and you could allocate GWorlds in VRAM a CopyBits
would always tears in VRAM but not in normal ram.
It's consistent with blitting from the bottom up cause the
bottom portion of the stimulus is ahead of the top portion and
the higher your resolution the further down the screen the tear
appears. I know the Mac page flips
but I don't know about Windows or whether this is in the ATI
driver or the Windows side. If it's on the Windows side it should
appear on all cards unless the blit speed is so fast that a whole
frame can be blitted during the VBL. Has anyone else seen this?
Thanks much,

Doug Taylor


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