Re: [stella] Dragons & Dragsters

Subject: Re: [stella] Dragons & Dragsters
From: "Eckhard Stolberg" <Eckhard_Stolberg@xxxxxx>
Date: Mon, 9 Sep 2002 21:24:23 +0200
> My idea was now, to use this trick in a Sea Wolf port, and to downsize
> it to 3 or 4 sprites. This'd provide ships & subs with 24/32 pixels
> resolution.
> would be doable per (2LK?) scannline, plus setting different sprite
> colors per line.
> Maybe Eckhard or Rob would like to comment on the idea in general, and
> if they'd consider it doable that way?

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.

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.

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.

Ciao, Eckhard Stolberg

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