Path: utzoo!utgpu!jarvis.csri.toronto.edu!cs.utexas.edu!tut.cis.ohio-state.edu!ucbvax!ucdavis!iris!rogers
From: rogers@iris.ucdavis.edu (Brewski Rogers)
Newsgroups: comp.sys.amiga.tech
Subject: Re: Fast Scrolling
Summary: pain and suffering
Keywords: scrolling,spam
Message-ID: <6072@ucdavis.ucdavis.edu>
Date: 29 Nov 89 02:40:57 GMT
References: <762@milton.acs.washington.edu>
Sender: uucp@ucdavis.ucdavis.edu
Reply-To: rogers@iris.ucdavis.edu (Brewski Rogers)
Organization: U.C. Davis - Department of Electrical Engineering and Computer Science
Lines: 48

In article <762@milton.acs.washington.edu> zeno@milton.acs.washington.edu (Sean Lamont) writes:
>
>This is a repost, since nobody wanted to answer my question.
>
>I am trying to do horizontal smooth scrolling.  I have tried two methods,
>one using SCROLLRASTPORT and one using SCROLLVPORT.
>
>Problems I want to solve:
>
>1)  I can't GET SCROLLVPORT to work at all!!! I gave it the VPORT record    
>    of my screen, but it did nothing.  I've tried this in several
>vport environments. 
>
>2) It's TOO SLOW!  A SCROLLRASTPORT takes far too much time to scroll
>anything of any substance. (like a 400 x 200 5-plane bitmap) I know
>it's possible to move bitmaps much faster (for example, Screen sizing)
>How would one go about making a FAST scroll?
>
>|      Sean T. Lamont          |                                         |
>|University of Washington      |  "Wave upon wave of demented avengers   |
>|ZENO@milton.acs.washington.edu|   march cheerfull y out of obscurity    |
>|   Savery hall, room 135.     |         into the dream"- P. Floyd       |

The only really *FAST* (That I know of, anyhow) way to scroll a view
is to take control of the copper list, or create your own copper list.

Once you have done this, you can simply change a couple of bytes in the
copper list, which takes almost zero cpu time, and you will have smooth
scrolling. Of course the whole thing tends to be a major pain in the
ass if you want intuition compatibility, but at least its possible.

One cheapo way you might want to experiment with, is to have intuition
allocate your copper list for you (simply open a screen) And then
search through it looking for the copper commands you want to modify.
Of course, that's not OS friendly, but it's probably a fairly quick
and dirty way to do it.

Basically, there are NO fast intuition routines to scroll your
screens View. This may be connected to the fact that most screens
can be dragged up and down the screen...

Good Luck.

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