Path: utzoo!mnetor!uunet!lll-winken!lll-tis!ames!ncar!gatech!bloom-beacon!mit-eddie!mit-amt!dlleigh
From: dlleigh@mit-amt.MEDIA.MIT.EDU (Darren L. Leigh)
Newsgroups: comp.sys.amiga.tech
Subject: Horizontal scrolling problems
Message-ID: <2465@mit-amt.MEDIA.MIT.EDU>
Date: 10 May 88 04:46:15 GMT
Reply-To: dlleigh@media-lab.media.mit.edu.UUCP (Darren L. Leigh)
Organization: MIT Media Lab, Cambridge MA
Lines: 21

I am trying to create a hi-res, interlaced horizontally scrolling
display for use in my heart monitor project.  I have been having some
weird problems with wide bitmaps and with the ScrollVPort function.

When the bitmap I am using is 1024 or fewer pixels wide, the display
is fine and I just get some hashing when I call ScrollVPort (I know
the docs said there would be some hashing, but that much?!?).  When
the bitmap is 1025 or more pixels wide, I get junk on the screen (even
after clearing the associated rastport, and without doing any
scrolling).  The junk seems to scroll OK, but jumps around a lot.  I
don't seem to be able to draw onto the junk either.

The bitmap in question is attached to the second rasinfo structure of
a dual playfield display (many thanks to those who helped me get that
working), but I get the same problem with single playfield displays.

Am I doing something wrong?  Is there a bug?  Or am I just going crazy?

=============================================================================
 Darren Leigh			dlleigh@media-lab.mit.edu
 362 Memorial Dr.               mit-amt!dlleigh
 Cambridge, MA 02139