nanogui: Flicker with dynamic images
Subject:
Re: [nanogui] Re: Flicker with dynamic images
From:
"Aaron J. Grier" ####@####.####
Date:
28 Apr 2009 00:19:14 -0000
Message-Id: <20090428001904.GI22974@arwen.poofy.goof.com>
On Mon, Apr 27, 2009 at 08:34:19AM -0400, Robert S. Grimes wrote:
> Aaron J. Grier wrote:
> >have you attempted to write some small simple standalone nano-X
> >programs to check the blit operations?
> No, not yet - I kind of hoped the demos would serve that purpose.
> I've been a bit reluctant to sort out the Makefile requirements, but I
> suppose that's not terribly difficult, right? Is there a good sample
> to start from?
for this level of testing, you could get by just by adding the proper
link flags to your standalone program. (-L and -l)
the demos exercise things in aggregate -- it would be nice to know the
smallest sequence of nano-X calls that demonstrate your shearing issues
and work on a solution from there. I suspect this may not be a nano-X
specific problem.
> A tip from Aaron Grier led me to realize I could rule out (or in!) the
> framebuffer as the culprit, by simply writing directly to it using
> open(), lseek(), and write(). Doing so, I have been able to confirm
> that the framebuffer appears to be working just fine. So I'm pretty
> sure it ain't the hardware...
the linux framebuffer driver mmap()s the framebuffer and writes to it
directly. did you also check this with your standlone test? the
framebuffer device driver may be doing additional locking / retrace for
a write() vs direct mmap() access. doing repeated framebuffer writes in
a tight loop may also be triggering problems.
> >which low-level driver is nano-X using? (one of the stock fblin
> >ones?)
>
> I believe so, but I'm not sure how to check that - how do I determine
> which driver is in use? Or for that matter, which are available?
(short brute force answer)
trace through GdOpenScreen() and see where you end up. (:
(longer brute force answer)
what functions are pointed to in the global scrdev struct ?
--
Aaron J. Grier | "Not your ordinary poofy goof." | ####@####.####
