Date:	Fri, 10 Mar 2000 20:33:14 +0600 (LKT)
From:	Kalum Somaratna aka Grendel <evilgrendel AT gmx DOT net>
X-Sender:	root AT darkstar DOT grendel DOT net
To:	djgpp AT delorie DOT com
Subject:	Re: Page Flipping with Allegro?
Message-ID:	<Pine.LNX.4.10.10003102032460.5016-100000@darkstar.grendel.net>
MIME-Version:	1.0
Reply-To:	djgpp AT delorie DOT com

On Thu, 9 Mar 2000, Al Morgan wrote:

> What is a good method to to page flipping with allegro?  I tried using
> blit(), along with a virtual screen for drawing on, but it wen't d4amned
> slow.  

Understandably this method is very slow mecause the amount of memory blit
has to transfer from the "virtual screen" to the screen memory per frame.

>I tried using scroll_screen, with calling set_gfx_mode with twice the
> y value, 

scroll_screen should do the trick but you might want to check it's return
value to see whether the particular driver or mode *supports this kind of
hardware scrolling*. 


>and some more code along with it to handle the flipping and such,

?? AFAIK scroll_screen does wait for the vsync before modifying any
registers, so what exactly is this code that you wrote to handle the
flipping.


> but there's horrible flicker.

Could you please tell us what graphics mode you are programming in etc..
Actually posting your code (if it is too large at least the smallest
possible portion that shows this problem) would help the most.

Grendel 

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:)

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