[haiku-appserver] Re: drawing thread

  • From: "Rudolf" <drivers.be-hold@xxxxxxxxxxxx>
  • To: haiku-appserver@xxxxxxxxxxxxx
  • Date: Mon, 01 Nov 2004 13:11:51 +0100 CET


ADI wrote:

> > The difference between the setup as below, and the triple setup, is 
> > that in the setup below the blit from back to front buffer has to 
> > be 
> > done and completed _during_ retrace (doable I would guess);
> > While with the triple version you only need to flip during retrace. 
> > Actual drawing from back to 'front' buffer may here be much slower.
>       True. But then again, in the triple buffering schema, don't you 
> need to draw everything in every 
> flippable buffer? Isn't it twice slower?
I guess you have to make sure the shown buffer is upto date in both 
setups. So it doesn't matter then if you update the same buffer over 
and over again, or if you do both alternatively (it's needed never at 
the same time)
Maybe it depends on implementation details like 'only updating on 
actual changes made in backbuffer' (or not).

>       What about apps that are directly using the frame buffer? Won't 
> they always draw into the first 
> flippable buffer?
No: back buffer. As far as they are concerned this _is_ the framebuffer 
I'd say. It's up to 'another process' to make that buffer shown after 
the next upcoming retrace.


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