From: Shawn Hargreaves <Shawn AT talula DOT demon DOT co DOT uk>
Newsgroups: comp.os.msdos.djgpp
Subject: Re: Tile based scrolling?
Date: Fri, 17 Jan 1997 20:30:00 +0000
Organization: None
Lines: 25
Distribution: world
Message-ID: <QgYHvlAIF+3yEwIc@talula.demon.co.uk>
References: <5bjnrh$bu2 AT dailyplanet DOT wam DOT umd DOT edu>
NNTP-Posting-Host: talula.demon.co.uk
MIME-Version: 1.0
To: djgpp AT delorie DOT com
DJ-Gateway: from newsgroup comp.os.msdos.djgpp

James Jeffrey Benjamin writes:
>I'm slowly working on a tile based engine using Allegro (mainly for
>640x480) and it has become prone to bugs. Anyway, what I'm doing is double
>buffer with blitting (moving) the virtual screen around as I add new rows
>of sprites. Is this faster or slower with the conventional way of just
>rewriting every (compiled) sprite onto the screen buffer? I know my way
>will get quite complex when I introduce parallex srolling. Sprite by
>sprite is easier, but is it faster?

It really depends on the details of your program (sorry, I don't have
any easy answer for you :-)

If a lot of the screen stays the same from one frame to the next (true
for many tile-based systems), your approach will probably save a lot of
time. If it scrolls every frame, though, rather than just when you reach
the edge of the screen, and certainly if you are doing parallax effects,
a brute-force redraw would almost certainly be faster (I can't think of
any way to do as-required redraws on a parallaxed screen, unless you
restrict the display to each different horizontal line belonging to a
single parallax layer).

/*
 *  Shawn Hargreaves - shawn AT talula DOT demon DOT co DOT uk - http://www.talula.demon.co.uk/
 *  Ghoti: 'gh' as in 'enough', 'o' as in 'women', and 'ti' as in 'nation'.
 */