Re: [stella] 11 Invaders "Reloaded"

Subject: Re: [stella] 11 Invaders "Reloaded"
From: "Thomas Jentzsch" <tjentzsch@xxxxxx>
Date: Thu, 27 Nov 2003 09:42:33 +0100
Andrew wrote:
> I think the invaders are vertically spaced too far, so I'd suggest you have
> a look at that optimisation sooner rather than later.  

Done that already (-3 scanlines). :-) 

But I may (have to) sacrifize one of those scanlines, so that I can display 
the missile (or missiles) during the spacing scanlines too. Do you think
that this would be an important improvement? 

> Probably only 10 invaders/row would be all you'd be able to fit and have 
> reasonable horizontal movement - 

I think I would let the player decide how many invaders he wants to 
fight. And even with the current 11 invaders they could move to 11 
different positions, which still is a one position improvement. ;-)

> ...but hey, it's pretty impressive right now.  


> My gut feeling, though, is that since we have Space Instigators - ANY 
> future Space Invaders effort will need to be a perfect clone.

100% agreed. If I'll make a game out of it, there will be a mode that 
will matches the arcade as close as possible on the Atari 2600. But I 
am planning to include a lot of variations, like in Space Invaders 2600
(depending on the ROM/RAM space). And maybe we'll find find some 
new variation ideas while discussing.

I am not sure about the bunkers yet. My old demo featured 3 quite
larger bunkers, while the original arcade game had 4 of them, which 
would be ~11(?) pixels wide when converted to the 2600.

So what would be better, 3 x 15 pixel bunkers or 4 x 8 pixel bunkers?

Dennis wrote:
> looked at the source (very briefly). How much of this is your old code 
> and how much was changed? I wish I had it with me now. 

I have rewritten this from scratch, only the invader graphics have been 
copied, plus a few ideas. The old code used a different kernel trick and
a different storage for the invaders status. But since it was a bit more
advanced in progress I might be able to copy some more code.

> I want to know how many RAM bytes the code takes up. 

Currently 46 bytes (I already managed to optimize one byte) and maybe I
will use RTS or BRK instead of the jmp, so that will save another two bytes
there (but increase stack usage).

Albert wrote:
> I haven't had a chance to try it yet--I will endeavor to do so soon.   
> :)  Since you said it doesn't work well in emulation, I need to try it  
> on a real system..

Definitely, but I hope "someone" will improve one of the existing 
emulators soon.


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