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? :-)
Greetings,
Manuel
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