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  • Joined: 28 Sep 1999
  • Posts: 1197
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Anyone have lightgun info?
Post Posted: Thu Feb 17, 2000 10:38 pm
I've been thinking of adding support for the SMS lightgun, but
the documentation that's available doesn't really cover it well.

I know you read the line and pixel position from ports 7E/7F.
What I'd be interested in is how the lightgun bits in port DD
are supposed to work, and if anybody has some theories about
how the gun 'senses' target objects. I'm guessing it's like
the NES where it can see bright objects, like white sprites
and background tiles.

And I know I've asked this before, but can anyone point out
where the backdrop color (reg 7) is actually used? I'm fairly
certain it has nothing to do with the screen enable bit nor
the color showing through transparent background tiles.
That said, I haven't found any games that look incorrect by
my method of totally ignoring the backdrop color. :)


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  • Joined: 24 Jun 1999
  • Posts: 1732
  • Location: Paris, France
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Post Posted: Fri Feb 18, 2000 5:54 am
Quote
> I've been thinking of adding support for the SMS lightgun, but
> the documentation that's available doesn't really cover it well.
> I know you read the line and pixel position from ports 7E/7F.
> What I'd be interested in is how the lightgun bits in port DD
> are supposed to work, and if anybody has some theories about
> how the gun 'senses' target objects. I'm guessing it's like
> the NES where it can see bright objects, like white sprites
> and background tiles.

LIGHTGUN TECHNICAL INFORMATIONS
The bit in port DD is 0 when the lightgun point to a while pixel.
That's *everything* you have to know, truly.

[..]
Quote
> And I know I've asked this before, but can anyone point out
> where the backdrop color (reg 7) is actually used? I'm fairly
> certain it has nothing to do with the screen enable bit nor
> the color showing through transparent background tiles.
> That said, I haven't found any games that look incorrect by
> my method of totally ignoring the backdrop color. :)

Cool! then I first got it right a while ago ;-)
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