On Thu, 17 Jan 2002, Martin Pottendorfer wrote:
hi,
Mark Vojkovich [EMAIL PROTECTED] wrote on Wed, 16 May 2001 11:32:20 -0700 (PDT)
On Wed, 16 May 2001, Peter Ronnquist wrote:
Hello,
I am trying to figure out how to update the screen
during vertical retrace. Is this possible with Xfree?
No. Not in any portable way. Only if the client knows
hardware specifics and runs as root and pokes registers.
If you are using OpenGL, your OpenGL implementation may
be able to do buffer swaps synced to the retrace. Probably
not though.
Mark.
Sorry to quote a quite old posting.
Just a short question related to the topic above:
Isn't the following fairly portable without OpenGL (at least to
architectures where DGA2 is available)?
Yes, if you want to be limited to running under DGA2.
It's not useful outside of DGA.
Mark.
[ From README.DGA ]:
void XDGASetViewport(
Display *dpy,
int screen,
int x,
int y,
int flags
);
[...]
viewportFlags
Any of the following may be OR'd together:
XDGAFlipRetrace
Indicates that the hardware can switch viewports during
the vertical retrace.
XDGAFlipImmediate
Indicates that the hardware can switch viewports immediately
without waiting for the vertical retrace.
[...]
I'm using this to get smooth animations with DGA2, and to some extent
it works. As it's not perfect (probably my fault) I'm still interested
in this topic.
thanx,
martin
PS: please CC to my address above, as I'm not subscribed to the Xpert
list. Thanx.
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