Re: [stella] Have kernel, need game!

Subject: Re: [stella] Have kernel, need game!
From: janhagelskamp@xxxxxx
Date: Sat, 21 Jun 2003 17:29:01 +0200 (MEST)

this scrolling is great work. I dont want to respond on your work but want
to come up with an idea for this scrolling work. There is a game for the palm
software called "SFcave" that is a really great and simple game and I allways
thought this would be a great game for the Atari 2600. When i saw this code,
I thought the SFcave would be a great Game Idea.

There is a homepage for this game here:

And there is even a java Version on the web:

Just try it, its really a great gameplay

I´m not very good in programming games for the 2600. But maybe there is
somebody who is taking this idea for a new Atari 2600 Game. As you can see on the
SFcave Homepage, the source is free for porting on other systems. So what do
you think?


> Hi,
> I have been always wondering how it would be possible to create a
> horizontal scrolling cave which is a bit more complex and flexible than
> the usual 2600 ones.
> The idea I had was to combine segments with different gradients. And I
> needed to do that inside the kernel. The minimal width of a segment
> should be 7 pixel, so that there are no more than two segments in one
> PF block.
> Then I "somehow" had to combine the two segments. This was a problem,
> because simple ORing or ANDing didn't work. It took a while until
> it finally "clicked". This is the basic kernel code:
>   lda (seg0),y
>   and (seg1),y
>   eor eorVal   ; !!!
>   sta PFx
> So the whole trick is EORing the result when necessary! :-)
> I am quite happy with this solution, but before I continue working on
> it, I would like to ask for comments. Maybe anybody knows an even better
> (faster, compact) solution.
> The attached binary and code shows the current WIP.
> The kernel is still very basic.
> - It isn't using PF0 at all, so the width is limited. Adding PF0 looks
>   possible, but it may need too much RAM and kernel CPU time, which
>   might be more useful for other things.
> - The top and bottom of the cave are currently completely separated. But
>   I am planing to let them overlap, so that the cave gets really tricky.
>   And I want to adjust the boundaries on the fly, so that the cave can
>   go up and down without being restricted to screen height.
> - Therefore the routine for the generation of the next segment will
>   probably get way more complicated than it is now.
> - Currently I am using 4 different gradients (+/- 0..3), adding more
>   will "only" require some ROM.
> Finally I will need some game IDEAs. Here are mine:
> - a paddle game, with a really fast scrolling cave, where you have to
>   avoid crashing into the walls and occasionally or evade shoot some
>   enemy objects
> - a game like this helicopter Jave applet where you only have to press a
>   button to control the height
> You see, this is going to become a quite simple, but hopefully fun game.
> So, what do you think? Which one is better? Any even better ideas?
> Have fun!
> Thomas                            
> _______________________________________________________
> Thomas Jentzsch         | *** Every bit is sacred ! ***
> tjentzsch at web dot de |

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