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Mail Archives: djgpp/1997/12/06/16:33:10

From: Shawn Hargreaves <Shawn AT talula DOT demon DOT co DOT uk>
Newsgroups: comp.os.msdos.djgpp
Subject: Re: Allegro graphics speed: 16 bit vs. 8 bit
Date: Sat, 6 Dec 1997 16:26:30 +0000
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To: djgpp AT delorie DOT com
DJ-Gateway: from newsgroup comp.os.msdos.djgpp

Dave writes:
>How does the speed of 15 or 16 bit graphics compare to 8 bit?
>(when blitting to the screen, etc.)

It depends on which functions you are using. The time required to copy
or draw a pixel will increase along with the color depth, but the
calculations to decide where and what to copy will be the same in any
mode. So simple brute-force routines like blit() will be approximately
half as fast in a hicolor mode as when using 8 bit color, but there will
be very little speed difference for the more complex functions like
image stretching and rotation...

>Sorry I haven't just run at test, but I am wondering if anyone has a 
>quick answer before I spend a couple hours downloading, installing, and 
>writing new code for the next addition of Allegro 

You shouldn't have to write any new code: none of the changes are likely
to break existing programs (if they do, please let me know ASAP so I can
fix it!). I'm probably going to release an offical version of 3.0 in the
next week or two, so if download time is a problem for you it might be
worth waiting for that. But on the other hand, I can also provide a
small patch that will let you upgrade the beta version to the final
thing without redownloading it all, and in terms of catching bugs it is
useful for as many people as possible to try out the beta version while
it is still in beta...


--
Shawn Hargreaves - shawn AT talula DOT demon DOT co DOT uk - http://www.talula.demon.co.uk/
"Pigs use it for a tambourine" - Frank Zappa

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