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From: jms@tardis.Tymnet.COM (Joe Smith)
Newsgroups: comp.sys.amiga.hardware
Subject: Re: Text changes color while scrolling.
Summary: Setting up the blitter is a lot of overhead.
Message-ID: <1194@tardis.Tymnet.COM>
Date: 26 Aug 90 08:58:26 GMT
References: <7137@helios.TAMU.EDU> <35188@ut-emx.UUCP> <1180@tardis.Tymnet.COM> <35790@ut-emx.UUCP>
Reply-To: jms@tardis.Tymnet.COM (Joe Smith)
Organization: BT Tymnet, San Jose, CA
Lines: 21

In article <35790@ut-emx.UUCP> lshaw@walt.cc.utexas.edu (logan shaw) writes:
>What?  Why not just do it like this:
>
>for scanline = 1 to however_many_scanlines_there_are
>  for bitplane = 1 to however_many_bitplans_there_are
>    blit_a_single_scanline ();    
>
>That would _not_ require the neato Agnus, and would not take any longer.

Blitting 400 lines one line at a time takes a lot longer than doing all 400
in a single blit.  My guess is that it would take at least 10 times longer.

One of the arguments for not using the blitter (as opposed to a tight loop
running on a 68020) is that it takes several milliseconds to wait for the
blitter to finish its previous operation and then set up all the parameters
for a new blit.
-- 
Joe Smith (408)922-6220 | SMTP: jms@tardis.tymnet.com or jms@gemini.tymnet.com
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