delorie.com/archives/browse.cgi   search  
Mail Archives: djgpp/1997/08/07/09:21:55

From: ao950 AT FreeNet DOT Carleton DOT CA (Paul Derbyshire)
Newsgroups: comp.os.msdos.djgpp
Subject: Re: [Q]: Allegro scrolling question
Date: 7 Aug 1997 05:58:50 GMT
Organization: The National Capital FreeNet
Lines: 25
Message-ID: <5sbo6q$iri@freenet-news.carleton.ca>
References: <33E17022 DOT 102F AT cat DOT csiro DOT au>
Reply-To: ao950 AT FreeNet DOT Carleton DOT CA (Paul Derbyshire)
NNTP-Posting-Host: freenet5.carleton.ca
To: djgpp AT delorie DOT com
DJ-Gateway: from newsgroup comp.os.msdos.djgpp

Jonathon Ralston (j DOT ralston AT cat DOT csiro DOT au) writes:
> Hello Allegro programmers!
> 
> I wanted to write a 640 x 480 x 256 horizontal scrolling program, like
> the ex19.c demo. I increased the screen bitmap size and changed the
> other screen size variables accordingly.  However, I found that
> *everything* on the screen was scrolled, including the text line.
> 
> Is it possible to scroll only *part* of the screen while in an SVGA
> mode, e.g., a 640 x 400 window?  I noticed that ex19.c uses a mode X
> modex_split type function.  Does this mean that the split screen
> text/scrolling only exists in mode X?  Is there a version of
> scroll_screen() that scrolls only part of the screen, or a BITMAP
> buffer?

In SVGA modes? I think the only easy way to do it in SVGA is to keep the
stuff you want to not scroll in a memory bitmap and blit it to the screen
after each scroll. Of course it might then flicker a bit.

--
    .*.  Where feelings are concerned, answers are rarely simple [GeneDeWeese]
 -()  <  When I go to the theater, I always go straight to the "bag and mix"
    `*'  bulk candy section...because variety is the spice of life... [me]
Paul Derbyshire ao950 AT freenet DOT carleton DOT ca, http://chat.carleton.ca/~pderbysh

- Raw text -


  webmaster     delorie software   privacy  
  Copyright 2019   by DJ Delorie     Updated Jul 2019