Hi all,
has anyone ever considered using the video overlay for 3D page flipping?
It always bothered me that the page-flipping method used by the radeon
drivers is so complicated WRT 2D/3D interaction and it would even stop
working when (if?) we switch to allocating back buffers per-client. So I
thought, couldn't you use the video overlay to display the front buffer
and do page flipping by switching the video overlay between two front
buffers?
Potential advantages:
* 2D drawing would not be complicated by page flipping
* would work with per-client back buffers (just allocate two color
buffers instead of one and switch the overlay between them
instead of copying to the front buffer)
* would be configurable per-application (driconf, .drirc) instead
of per screen (xorg.conf)
* one page-flipping client could run even with other
non-page-flipping 3D clients active at the same time (currently
page flipping is completely disabled as soon as the second 3D
window opens)
* page-flipping client could have a different color depth from the
normal frame buffer
* smooth scaling of arbitrary resolutions to full screen size
would be possible
Disadvantages:
* watching movies via the Xv extension and page-flipping would not
be possible at the same time
* requires more dynamic memory management than currently exists in
most drivers with a static back buffer
* requires two off-screen buffers instead of just one
* on some hardware an enabled overlay may reduce 3D performance
slightly (it does on Savage hardware)
I have no immediate plans to implement such a page-flipping scheme. I'd
wait for some off-screen memory management to be in place first. Just
wanted to write down the idea before it catches dust.
Cheers,
Felix
--
| Felix Kühling <[EMAIL PROTECTED]> http://fxk.de.vu |
| PGP Fingerprint: 6A3C 9566 5B30 DDED 73C3 B152 151C 5CC1 D888 E595 |
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