Re: [stella] Dragons & Dragsters

Subject: Re: [stella] Dragons & Dragsters
From: Manuel Polik <cybergoth@xxxxxxxx>
Date: Mon, 09 Sep 2002 23:14:27 +0200
Hi Eckhard!

>I can see two possible problems with this setup. First 
you need to
>set the players to use multiple copies for displaying 
one large sprite.
>This also affects the missile graphics, so for 32-pixel 
ships you
>could only use the ball for torpedos. For 24-pixel 
ships you would have
>the ball and one missile, but if you need to display 
three torpedos
>in the same row, you can only have 16-pixel ships.

Aha. I thought about allowing six torpedos at once on 
screen, that is three per sub with 25/30Hz flicker.

So doing the 24 pixel resolution here seems to be the 
most reasonable compromise, with a max. of 4 torpedoes 
onscreen, 2 per sub.

>The other problem is that preloading the GRP registers 
and timing
>the writes to them takes a lot of cycles. It can be 
done during the
>76 cycles you have per scanline, but depending on where 
on the screen
>the ship is positioned, the display of your topedos 
might be off by
>one scanline.

I see. But fortunately, we are hopefully on safe grounds 
this time. The torpedos are going straight vertically, 
so no one can notice the *jump* we'd experience with 
horizontal movements, right?

>There is so much overhead that you can't start the 
positioning routine
>directly after a WSYNC, because then you wouldn't be 
able to display
>anything in the left part of the screen. You have to do 
one WSYNC at the
>start of the routine and then go through the actual 
display without using
>any WSYNCs during those lines. In the first karate demo 
I tried to change
>the background colour on some lines to give the picture 
some depth. But
>the change of colour would always happen in the middle 
of a scanline,
>depending on where the fighter was positioned. If you 
only use 24 pixels
>this might be manageable though.

Well, I thought about dividing the screen in fixed 
stripes, so the background color change can happen 
easily in a not-so-busy scanline between ships.

But I thought it'd be nice to have the ships colored 
themselves, which'd either require one additional color 
read and two writes of this value, or if that is not 
possible, maybe only some simpler color shading. Or 
clever graphical design of the ships, where for example 
the middle part wouldn't change it's color at all, but 
only the the sides.

Under this conditions, do you think we slowly reach a 
'doable' scenario? :-)


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