Re: How do I sync output changes to vertical retrace?

Mark Vojkovich wrote:
>   The only mechanism I know of is OpenGL.  Most OpenGL drivers have
> a mechanism to allow buffer swapping at vblank.
>   
Using DRM/DRI this works:

void waitForVSync()
{
if( card_fd < 0 )
card_fd = open( "/dev/dri/card0", O_RDONLY );

drm_wait_vblank_t wait_vblank;
wait_vblank.request.type = _DRM_VBLANK_RELATIVE;
wait_vblank.request.sequence = 1;
wait_vblank.request.signal = 0;

int rc;
do
{
wait_vblank.request.type = _DRM_VBLANK_RELATIVE;
rc = ioctl( card_fd, DRM_IOCTL_WAIT_VBLANK, &wait_vblank );
}
while( rc != 0 && errno == EINTR );
}


Barry