static void
wait_for_vblank (ClutterBackendGLX *backend_glx)
{
if (backend_glx->vblank_type == CLUTTER_VBLANK_NONE)
return;
if (backend_glx->wait_video_sync)
{
unsigned int retraceCount;
CLUTTER_NOTE (BACKEND, "Waiting for vblank (wait_video_sync)");
backend_glx->get_video_sync (&retraceCount);
backend_glx->wait_video_sync (2,
(retraceCount + 1) % 2,
&retraceCount);
}
else
{
#ifdef HAVE_DRM
drm_wait_vblank_t blank;
CLUTTER_NOTE (BACKEND, "Waiting for vblank (drm)");
blank.request.type = _DRM_VBLANK_RELATIVE;
blank.request.sequence = 1;
blank.request.signal = 0;
drm_wait_vblank (backend_glx->dri_fd, &blank);
#else
CLUTTER_NOTE (BACKEND, "No vblank mechanism found");
#endif /* HAVE_DRM */
}
}
static void
glx_wait_for_vblank (ClutterBackendGLX *backend_glx)
{
/* If we are going to wait for VBLANK manually, we not only need
* to flush out pending drawing to the GPU before we sleep, we
* need to wait for it to finish. Otherwise, we may end up with
* the situation:
*
* - We finish drawing - GPU drawing continues
* - We go to sleep - GPU drawing continues
* VBLANK - We call glXSwapBuffers - GPU drawing continues
* - GPU drawing continues
* - Swap buffers happens
*
* Producing a tear. Calling glFinish() first will cause us to properly
* wait for the next VBLANK before we swap. This obviously does not
* happen when we use GLX_SWAP and let the driver do the right thing
*/
switch (backend_glx->vblank_type)
{
case CLUTTER_VBLANK_GLX_SWAP:
/* Nothing */
break;
case CLUTTER_VBLANK_GLX:
{
unsigned int retraceCount;
glFinish ();
backend_glx->get_video_sync (&retraceCount);
backend_glx->wait_video_sync (2,
(retraceCount + 1) % 2,
&retraceCount);
}
break;
case CLUTTER_VBLANK_DRI:
#ifdef __linux__
{
drm_wait_vblank_t blank;
glFinish ();
blank.request.type = DRM_VBLANK_RELATIVE;
blank.request.sequence = 1;
blank.request.signal = 0;
drm_wait_vblank (backend_glx->dri_fd, &blank);
}
#endif
break;
case CLUTTER_VBLANK_NONE:
default:
break;
}
}
