Screen tearing with direct draw

Assuming your using the DdFlip function, its one of the flags in the DD_FLIPDATA structure.  DirectDraw has been the name for a few API's that might not be the one you're asking about.

Hi No im not Flip I am using blit from back buffer to primary surface in a windows form not full screen

Hello again nchannon, always a enjoy your questions.

Gimme a clue, what variety of DirectDraw is this and what version of Windows?  Are you not using DdFlip because that function doesn't exist in the DD in question?

Hi Im glad you enjoy my questions your answers have been very helpful in the past.
I am using DD version 7 running on XP.
No Im not using the Flip function m_pddsPrimary->Flip( NULL, DDFLIP_WAIT ) because im running in windowed view and have set lpDD->SetCooperativeLevel( hwnd, DDSCL_NORMAL)
When I copy my backbuffer to the primary surface to display on the monitor I call this:
 m_pddsPrimary->Blt(&rcDest,   m_pddsBackBuffer,  &rcSrc,  DDBLT_WAIT,  NULL); but I get this tearing effect due to the refresh rate from my monitor and the refresh rate from DD not being in sync
hope you can help me out with this.

Hi I think this is the solution to my tearing problem:

dd->WaitForVerticalBlank(DDWAITVB_BLOCKBEGIN, 0);
m_pddsPrimary->Blt(&rcDest,   m_pddsBackBuffer,  &rcSrc,  DDBLT_WAIT,  NULL);

if not ill post back

Yeah, you've got it, problem solved I think.  Feel free to delete the question, I wont object.

Thats interesting, the two methods are waiting for the same event.  Maybe WaitForVerticalBlank stops both cores or skips a frame?

I guess the most CPU efficient way to do this would be to have some kind of vertical blank callback, so that the program doesn't wait at all.  You could get a decent approximation with a timer.  Get it to trigger an event after 20 milliseconds, do the frame processing, wait for the vertical blank then wait another 20 milliseconds.  That way the program would be idle some of the time.

On the plus side, the program is running 0.6%, if vertical blank takes it to 10%, that suggests it could do about 16 times as much work between each frame.

I found the solution my self