[haiku-appserver] Re: drawing thread

  • From: Adi Oanca <adioanca@xxxxxxxxxxxxxx>
  • To: haiku-appserver@xxxxxxxxxxxxx
  • Date: Mon, 01 Nov 2004 12:53:42 +0200

Good day,

Rudolf wrote:
> Adi,
> 
> 
>>      What I don't get:
>>      Where is the third buffer?
> 
> All three on graphicscard memory.
> two buffers for flipping, one as the replacement for the current 
> visible buffer.
> 
> 
>>      Why not just draw into the offscreen buffer then page flip?
> 
> Because the third buffer will make the whole doublebuffer things 
> 'invisible' to apps etc. The stuff will behave transparant, as if you 
> would be drawing directly onscreen.
> That's also the reason why I think I can set this up inside the driver 
> to work with standard R5. as the 'proof of concept'. 
> I am not entirely sure if in the end some support is needed in 
> app_Server or if I can keep it entirely local. (engine management gets 
> more tricky)
> 
> 
>>Blit from front buffer to the back one so the two buffer be identical 
>>at this moment.
> 
> So, can be done, but adding the third buffer makes the whole setup 
> 'transparant' to the system and apps, while without this a lot of 
> app_server support is needed, and also BDirectWindow apps get into 
> trouble (I think?)

        I have some doubts.
        Are you talking about page flipping? Once we've done that, if I'm not 
wrong, we loose compatibility 
with R5 - BWindowScreen; as it writes to the location which is now the 
backbuffer.

        IMHO, the only solution, is to always draw into the backbuffer and then 
blit into front buffer 
during retrace.

        I don't see how triple buffering could solve our/(this?) problem. (??)


bye,
Adi.

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