On May 14, 2005, at 11:16 AM, Shawn Erickson wrote:
On May 14, 2005, at 10:54 AM, Lorenzo wrote:
I compiled my OpenGL app with XCode 2.0.
On Panther is everything ok. On Tiger I get this problem.
When another window of another application (e.g. a Finder window,
an XCode
window...) is over my OpenGL window (even partially), that
application runs
very very slow. If I drag that window out of the OpenGL window,
that program
turns back to work well.
A side note I don't see what you describe above happening on my
Dual 2GHz G5 with 6800 GT (and two 23" monitors attached) when
using one of the GLUT examples ("atlantis timing"). I however do
see the GLUT example slowing down its animation to the refresh rate
of the monitor when the shadow of another window is over the
examples content. The example uses glutSwapBuffers at the end of
each draw cycle. It stands to reason when the window is not
overlaid by any other window (aka opengl surfaces) then buffer
swapping can happen as fast as the hardware can do it. If a window
overlays things then it is likely clamped to the swap rate of
window manager for its surfaces which likely is no faster then the
display refresh rate (I have only LCDs at home so I cannot twiddle
with refresh rates to confirm).
This is a very real problem, and affects graphics performance for
most app's. In profiling, glFlush() takes approx 5 times longer to
complete on Tiger vs. Panther. Window dragging is slower, and drops
to 1/3 speed or less when a window spans more than one display, and
on my Radon 9000 is slower on the non-main display. It's as if CGS
is attempting to force VBL sync "again", competing with other sync
API's. Several bugs filed. I'd post the #'s but Radar is currently
down.
--
Shaun Wexler
MacFOH http://www.macfoh.com
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