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From: gbbrooks@sybil.cs.Buffalo.EDU (G. Brandon Brooks)
Newsgroups: comp.sys.amiga.tech
Subject: Re: Fast Scrolling
Keywords: scroll
Message-ID: <13962@eerie.acsu.Buffalo.EDU>
Date: 30 Nov 89 04:50:49 GMT
References: <13939@eerie.acsu.Buffalo.EDU> <6096@ucdavis.ucdavis.edu>
Sender: nobody@acsu.buffalo.edu
Reply-To: gbbrooks@sybil.cs.Buffalo.EDU.UUCP (G. Brandon Brooks)
Organization: SUNY/Buffalo Computer Science
Lines: 28

In article <6096@ucdavis.ucdavis.edu> rogers@iris.ucdavis.edu (Brewski Rogers) writes:
>
>ScrollVPort is actually pretty slow. Also, in the RKM's it is described
>as having a slight bug where it may flicker periodically.

	Having programmed an Atari 800 previously, and upon spotting this
command, I used it and noticed the flicker. It doesn't seem to be a bug
according to what my knowledge of the Atari is. I just use a Wsync(), or the
Amiga equivalent to this, WaitTOF. The flickering is then eliminated.
	
>Doesn't ScrollVPort do a MergeCopList (or whatever its called)?
	
	Maybe, but my "Amiga Programmer's Handbook", ScrollVPort, pg. 281
doesn't say that it does. It DOES get the screen's new copperlist and
fiddles with it.

>Basically, any system command is going to have to do some big data
>moving to get the screen's new copperlist to work with the screen-dragging
>the O.S. supports.
>
>It depends on how much CPU time you want to spend scrolling your view.
>

	I am in the midst of programming a scrolling game on my Amiga. So
far, using ScrollVPort seems to do the job very quickly. If someone knows
how to scroll a view faster, with less CPU time, please enlighten me!

		-Brandon!