Re: A86: SCrolling
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Re: A86: SCrolling
Ah, that's neat to know. Redrawing that one pixel edge is really a pain.
It's a map lookup, putsprite and findpixel all rolled into one nice, neat
mess of code. I can't wait to see your new engine.
Is anyone making or thinking about making a 4 way scroller, like Mario 3 or
Commander Keen? A game like that would really be awsome.
-----Original Message-----
From: Jimmy Mårdell <yarin@acc.umu.se>
To: assembly-86@lists.ticalc.org <assembly-86@lists.ticalc.org>
Date: Tuesday, October 27, 1998 7:36 PM
Subject: Re: A86: SCrolling
>
>At 16:09 1998-10-27 -0600, you wrote:
>>
>>Could you shed some light on the more complex and faster ways? rotate \
>>increment/decrement instructions are the fastest ways that I can see to
>>shift bytes around. I thought about using port 0 for hardware scrolling,
>>but would only work for up and down, and that would only scroll it in
>>increments of 256 bytes, or 1/4 of the screen.
>
>Actually, the scrolling part can't be made faster, but that's not the
point.
>When you scroll left<->right, you always have to fill in the newly appeared
>column to the left/right, and that takes quite some time actually. I've
>developed another scrolling engine which is about the same speed, but
>much much more flexible. For instance, you can scroll two or three
>pixels at a time instead of just one. As I said, it's very complex
involving
>using of all register & shadow registers, 2k lookup tables, dynamic
>code creation (the 16k at RAM page 1 comes in handy :) ) Also, sprite
>routines with the new engine (where the scrolling is already working)
>are extremely fast and doesn't require clipping (that's done
automatically).
>
>I will release the engine (and source of course) when I've finished with
>the sprite routines and put together a cool demo.
>
>--
>Real name: Jimmy Mårdell
>Email: mailto:yarin@acc.umu.se
>Homepage: http://www.acc.umu.se/~yarin/
>
>Icarus Productions homepage: http://icarus.ganymed.org/
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