It seems that using a PresentInterval of one in
windowed mode causes my application to miss frames periodically. About 1/10th
of a second every couple of seconds. This doesn't happen in full screen mode.
Now what's really weird is that if I hibernate my computer with the program
running, when it comes back the windowed mode doesn't vsync at all. I get about
30 FPS with lots of tearing, and Present() taking lots of time (sometimes 40
milliseconds). Full screen mode still works. Switching back to windowed mode
(tearing down the DirectX device, and creating a new one) doesn't solve the
problem. It still doesn't sync. Re-running the application fixes the
problem.
So I decided to write my own sync in a high
priority thread. Come to find out that Thread.Sleep() has a resolution of 1
millisecond until I hibernate the computer. When the computer comes back to
life, Thread.Sleep() now has a resolution of 10 milliseconds. This happens even
if I use timeBeginPeriod(1) and timeEndPeriod().
My guess is that DirectX (in windowed mode only)
uses a high resolution timer to synchronize, and then fails miserably when the
timer switches back to a resolution of 10 milliseconds.
So anyone know what's going on, and how to get
DirectX to synchronize to frames in Windowed mode without having these
problems Or, point me to a better forum if this isn't the right
place
Thanks,
Jeremy
Vsync and timer problems
veeta
If you do use ONE for both, I don't know -- sounds weird to me. Does hibernation affect the timer resolution for your application only, or for all applications (Try launching a new app that tests the timer). Hibernation requires driver support, so maybe some driver isn't restoring its state correctly.