Subject: Problems with blitting blocks fast enough for HW scroller
From: Dave Cole <[email-masked]>
To: [email-masked] (Blitz)
Date: Wed, 3 Aug 1994 23:00:16 +1000 (EST)

G'day all,

  I am currently working on an 8-way hardware scrolling routine,
and have just come across a minor snag.
  Scrolling to the right is fine (as should to the left when I get
that going), but scrolling down (and consequently up), is causing
me difficulties.

  The problem seems to be that "block" doesn't blit to the screen
fast enough.  I'm trying to blit 20 blocks across the bottom of the
screen (just out of view), and across the top of the screen (again
just out of view.  I'm therefore trying to blit 40 blocks at once.
  When the scrolling is going, there is a very very minor jerk,
(hardly noticeble, but I can see it, and I don't like it!).  This
doesn't occur if I blit only 18 blocks on top and bottom (36 in
total).  

  I could just reduce the width of my displayed screen by 32
pixels, but would like full screen (and even overscan if possible),
but "block" isn't fast enough.

  What I would like to know is this:  Is there an even faster
blitting command than block??
  How have other people got around this problem??

Thanks in advance,
Dave

-----------------------------------------------------------
Dave Cole                      | Please contact me for info 
[email-masked]  | about
[email-masked]   |        The Warhammer 
[email-masked]   |         Compendium
-----------------------------------------------------------