Path: utzoo!utgpu!jarvis.csri.toronto.edu!mailrus!shadooby!samsung!usc!apple!excelan!sjsumcs!33014-18
From: 33014-18@sjsumcs.sjsu.edu (Eduardo Horvath)
Newsgroups: comp.sys.amiga.tech
Subject: Re: Fast/smooth/easy vertical scrolling
Message-ID: <1989Nov12.203553.18251@sjsumcs.sjsu.edu>
Date: 12 Nov 89 20:35:53 GMT
References: <993@mit-amt.MEDIA.MIT.EDU>
Reply-To: 33014-18@sjsumcs.SJSU.EDU (Eduardo Horvath)
Distribution: na
Organization: San Jose State University
Lines: 23

In article <993@mit-amt.MEDIA.MIT.EDU> dlleigh@media-lab.media.mit.edu.UUCP (Darren Leigh) writes:
>I'm looking for various ways to do fast and smooth vertical scrolling
>of text.  Both up and down scrolling are necessary.  Prefereably the
>scrolling should take as little CPU time as possible.  I also need to
>have the sprites usable over the entire screen.
>

	You could consider creating a really big bitmap, and changing the
modulo for the start of the bitmap.  This takes almost zero cpu time.  If
the bitmap is 3x the height (width) of the screen, you can do a quick blit
to copy the bottom of the screen to the top, change the modulo to the top
of the screen, and then continue.


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