This very thing could occur in an application that uses client memory
to store vertices, such with the Vertex Array Range extension. If the
range isn't properly flushed or is modified in system memory as the
video card is trying to use it to draw with it, then you will see
flashes like this. The fact that it occurs more often on a fast card
or when you are dragging a window around would be because this is a
timing issue between when the application writes to the memory and when
the video card is reading from the same exact memory.
Chris
On Mar 24, 2005, at 11:50 PM, Warren DeLano wrote:
Does this sound familiar?
I have a GLUT-based OpenGL app (PyMOL) showing a flickering behavior
that is
sensitive to other OpenGL rendering activity on the screen. For
example, if
I set a molecular surface "rocking" in PyMOL and then drag a window in
the
Finder, specular lighting in PyMOL gets all flickery and occasionally
the
PyMOL will flash with a solid background color corresponding to one of
the
current drawing primitives. The problem is more pronounced on certain
systems than on others, and especially on late-model high-end systems
(e.g.
2.2 Ghz dual G5 with a GeForce 6800 Ultra). Apparently some users are
experiencing such severe problems that the app has become unusable.
My diagnosis isn't yet complete, but this issue does seem to be
hardware-specific, and may only occur with late-model nVidia cards &
recent
10.3.x and 10.4 beta releases. I have plenty of older nVidia and
ATI-based
hardware that doesn't show this issue. In fact, of the hardware I have
access to, only my G5 iMac currently shows the problem.
No bug report filed yet because I am not yet convinced this isn't a
problem
in my code. However, I am posting here on the off chance that someone
else
might have come across a similar problem recently, and could thus save
me
some time...
Thanks in advance for any comments!
Warren
--
Warren L. DeLano, Ph.D.
Principal Scientist
_______________________________________________
Do not post admin requests to the list. They will be ignored.
Mac-opengl mailing list (email@hidden)
Help/Unsubscribe/Update your Subscription:
http://lists.apple.com/mailman/options/mac-opengl/email@hidden
