Re: [stella] parallel efforts / Invaders

Subject: Re: [stella] parallel efforts / Invaders
From: "Eckhard Stolberg" <Eckhard_Stolberg@xxxxxx>
Date: Wed, 14 Mar 2001 21:21:41 +0100
> One thing that disturbed me a little bit was the recent clash with the
> 'crazy valet' program - where two brilliant programmers independantly
> decided to work on a secret project of essentially exactly the same game.
> I felt very sad when both the crazy-valet variants showed up - for it
> to me that both programmers, to some degree, must have felt a bit
> disappointed that somebody else was working on the same idea.  (I still
> to think about how the colour version was done).

Actually I wasn't disappointed either. I knew that Brian already
was selling his version, so I knew that mine wasn't the only one.
In fact it was Brian's version that introduced me to this fascinating
game. But there were some things that I didn't like about his version
(mainly the lack of colour and the fact that you couldn't chose the
level), so I decided to try to write one of my own. I didn't want
to release it at all, since I was using the levels from the board game,
but when Thomas posted his version and said that Brian didn't mind
some competition, I thought I'd share my code as well.

The colour version is pretty simple BTW. I just keep the colour
values for all the squares in an array, and then change the
background colour in every line on the fly. Since there are only
six squares per row, the VCS is fast enough to load the colour
values from the array. No need for self modifying code or anything.

> I do not plan, for the while, to take over Space Invaders.  I think that
> this sort of coding is probably still a bit beyond me.  I was delighted at
> the chance to have a good hack, though.  Personally, I don't think the
> 'together' invaders at the right of the columns is a problem.  During
> gameplay this will barely be noticeable.  I also don't think that one
> worry about pixel-resolution in horizontal movement.  In fact, every 3
> pixels is just fine (or even courser).  These things are distractions.
> invaders need to be as large as possible (ie: 8 pixels wide)... it makes a
> big difference to the look/feel.

The problem with 'together' invaders is that it happens to all invaders
that don't have a copy of the same player directly behind them. So if
you remove one invader from the formation, the invader two spots left
of him will be shifted two pixels to the left. You can see it, if you
look closely at Erik's version. And getting any missiles into the invaders
display of my version might be very tricky.

Ciao, Eckhard Stolberg

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