From:	a DOT gillett AT virgin DOT net (Andrew R. Gillett)
Newsgroups:	comp.os.msdos.djgpp
Subject:	Re: Allegro and blitting to screen
Date:	Sun, 19 Jul 1998 23:24:54 +0100
Organization:	Virgin Net Usenet Service
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Message-ID:	<MPG.101c82922011ae85989999@news.virgin.net>
References:	<6onnuh$12p$2 AT oravannahka DOT Helsinki DOT FI> <MPG DOT 101ad9bbc1569c84989988 AT news DOT virgin DOT net> <mvparvia DOT 900873261 AT snakemail DOT hut DOT fi>
NNTP-Posting-Host:	194.168.236.12
To:	djgpp AT delorie DOT com
DJ-Gateway:	from newsgroup comp.os.msdos.djgpp

In comp.os.msdos.djgpp, article <mvparvia DOT 900873261 AT snakemail DOT hut DOT fi>, 
Mikko V.I. Parviainen (mvparvia AT kvartsi DOT hut DOT fi) wrote:
> a DOT gillett AT virgin DOT net (Andrew R. Gillett) writes:
> >I've never understood the point of double-buffering. Are there any 
> >advantages over page flipping?
> 
> Some time ago I made some tests in 640*480*256 mode. I have an P100
> machine, with some very bad SVGA card. 
> My test program used the whole screen. First, I tried page flipping.
> It was annoyingly slow, so I decided to try double buffering, 
> because it was very quick to code. The speed gain was unbelievable.
> The blit was about two times as quick as with double buffering.
> I think that the cause of this effect was the slowness of
> video memory, but I am not sure. 

I can't see how double-buffering could be faster than page flipping. Were 
you using vsync() in the double-buffering version? If not, that's why it 
ran faster.

-- 
Andrew Gillett
http://argnet.fatal-design.com/
ICQ: 12142937

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