on 7/5/02 8:52 AM, KirkIsrael@xxxxxxxxxxxxx at KirkIsrael@xxxxxxxxxxxxx
wrote:
> the easiest thing might be to "throw away" a scanline, trial
> and error using NOPs 'til you're in the right place and then use
> RESP0/RESP1
That's the easiest way I could think of doing it. Is that pretty common? I
figured I should start checking out the Combat dissembly at some point...
> Currently my biggest issue is bounds checking. I've been trying to
> keep it mathematical, i.e. comparing the vertical position to certain
> constants for the floor and the ceiling, but I keep getting some odd
> behaviorial results...
Floor and ceiling are easy enough if you'll sacrifice a few scans to a solid
playfield the same color as the background. From the looks of the other
versions of JoustPong, you won't have a playfield graphic in the middle of
the screen either, so you could probably get away with using the same color
playfield [as background] for left and right as well. Then it's just an
issue of trapping collisions, which has to be easier.
That was my plan, anyhow. Course then when you start thinking about adding
variations on theme that do use a playfield, I suppose timing will rear its
head again. I've already had to dip into a two scanline kernel... Kinda
crappy wrt the player graphics. But checking for four things every line was
just too many cycles, quickDraw or no quickDraw.
Good luck,
Ruffin Bailey
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