From: "Johnny P." <gimli AT interaccess DOT com>
Newsgroups: comp.os.msdos.djgpp
Subject: Scrolling using Allegro...
Date: Tue, 9 Jun 1998 14:11:22 -0500
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To: djgpp AT delorie DOT com
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Hi,

I need to scroll around a virtual screen.  I am using Allegro's
scroll_screen() fxn and it works perfect when scrolling vertically.  When
scrolling horizontally, it is very jumpy and redraws incorrect parts of the
image.  Does Allegro's scroll_screen not use the pixel-panning register for
planar modes?  If not, is there an easy way to get this to work with djgpp?
I am in a 640 X 480 graphics mode using at least a 1024 X 1024 virtual
screen.  Is there a good 256-color mode with similar screen dimensions and
stability, BTW?

If scrolling horizontally is a problem, would it be easier to draw all
graphics to a 1024 X 1024 buffer (1,048,576 bytes for a 256-color
mode--kinda large) and then blit the active section to the screen?  What
would be a good way to do this?

Thanks,

Johnny P.