From:	John Allensworth <tarquin AT texas DOT net>
Newsgroups:	comp.os.msdos.djgpp
Subject:	Re: Quake isn't the be all and end all
Date:	03 Jun 1997 11:48:09 -0500
Organization:	Texas Networking, Inc.
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References:	<199705302154 DOT QAA24261 AT sendit DOT sendit DOT NoDak DOT edu>
	<5n0rk1$kc1$2 AT grissom DOT powerup DOT com DOT au>
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To:	djgpp AT delorie DOT com
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phreadd AT powerup DOT com DOT au (David Orme) writes:

> Apparently Michael Abrash used the brute force method to shove the screen 
> buffer do the screen (not paging). This is noticable even in the 320x240 

yes. In Zen of Graphics Programming, 2nd Ed., Abrash noted that during 
development, page-flipping was faster. They couldn't explain it, since they 
assumed that memcpy would be using movsd's, which should be faster. For a while
they took it as an unexplainable bonus, until while playing with the pentium's
profiling registers, Abrash noticed that the brute force memset was making
64000 writes (for 320x200), not 16000. It turned out that their version of the
DJGPP C library had a less than optimal memcpy. After they fixed that, the 
brute force was faster than page-flipping.

> resolution, but if you use a higher res it gets worse. During play I have 
> noticed that at times the lower half of the screen is at a different frame 
> than the top half. This may be due to the "blast" not being linked to the 
> retrace correctly, since it is most noticable when the sound is turned on.

Quake checks for retraces, it's just that it seems that your CPU/vid card 
can't shovel that many pixels per frame (wild guess) or perhaps they didn't use
the retrace checks in qtest.The requirement list doesn't say pentium for 
nothing (though a lot of that is because of the FPU)

> These problems are probably not noticable to those of you who use Pentiums, 
> but I use a 486DX100 and, since I don't have the speed that you do, I see 
> these things which are hidden by the Pentiums speed.

see above.

BTW, Zen of Graphics is a GREAT book. Also known as the one where he almost 
gives you the Quake engine :)

> +----------------------------------------+
> |   David                          \/\   |
> |   phreadd AT powerup DOT com DOT au         /\/   |
> |   powerup.com.au/~phreadd              |
> +----------------------------------------+
> |   "Striving for Excellence"            |
> +----------------------------------------+

-- 
John Allensworth --- tarquin AT texas DOT net --- ReaperMan on the QuakeServers
Author of XtraWeapons (except the homing missile, eject, and throwing axe) 
Industrial Strength Gaming    http://www.uk.digiserve.com/whiteoak/punktc/
Skrew Actura! Dem bastards stole my Bouncing Bettys! (incl. in XW19)

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