From:	ao950 AT FreeNet DOT Carleton DOT CA (Paul Derbyshire)
Newsgroups:	comp.os.msdos.djgpp
Subject:	Re: VESA DoubleBuffer flicker and SetGetDisplayStart func 0x07h
Date:	3 Mar 1997 05:31:46 GMT
Organization:	The National Capital FreeNet
Lines:	22
Message-ID:	<5fdno2$n7n@freenet-news.carleton.ca>
References:	<5f77ph$bf8 AT news DOT cableinet DOT net> <aI4FlBBCW2FzEw+5 AT talula DOT demon DOT co DOT uk> <5fblr1$a0r AT news DOT cableinet DOT net>
Reply-To:	ao950 AT FreeNet DOT Carleton DOT CA (Paul Derbyshire)
NNTP-Posting-Host:	freenet2.carleton.ca
To:	djgpp AT delorie DOT com
DJ-Gateway:	from newsgroup comp.os.msdos.djgpp

In my "pet project" I am using a double buffer like described. (I allocate
for three buffers, and use the third to hold the parallaxing background to
speed up redrawing, using fast aligned mode x blits.)
I never get any flicker running under DOS, and only wait for one retrace,
immediately before request_modex_scroll(newx,newy).
I also get from 20-50 fps...

(I have a "brake" to limit it to at most 50 fps, and a "smart motion"
routine so anytime something's x or y increases by a delta value, the
delta is effectively multiplied by 50 and divided by the true fps, which
is monitored at run time. Every loop a framecount is ++'ed. Every second,
using an Allegro timer int, it is compared with the old frmecount.)

Note: 20 fps is as fast as most peoples' eyes will update the picture to
the brain. 60 is the max possible because of the mode x 60Hz retrace.

--
    .*.  Where feelings are concerned, answers are rarely simple [GeneDeWeese]
 -()  <  When I go to the theater, I always go straight to the "bag and mix"
    `*'  bulk candy section...because variety is the spice of life... [me]
Paul Derbyshire ao950 AT freenet DOT carleton DOT ca, http://chat.carleton.ca/~pderbysh

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