IDirectDraw2::GetVerticalBlankStatus
HRESULT GetVerticalBlankStatus(LPBOOL lpbIsInVB);
Retrieves the status of the vertical blank.
·Returns DD_OK if successful, or one of the following error values otherwise:
lpbIsInVB
Address of the variable that will be filled with the status of the vertical blank. This parameter is TRUE if a vertical blank is occurring, and FALSE otherwise.
To synchronize with the vertical blank, use the IDirectDraw2::WaitForVerticalBlank method.