Subject: Re: [stella] Light gun/pen From: Chris Wilkson - MCD <cwilkson@xxxxxxxxxxxxx> Date: Tue, 30 Sep 1997 10:34:42 -0700 (PDT) |
> I think it's more than that with Atari systems at least, otherwise light > pens would not work as paint programs or pointing devices. Such a system > as you describe is far too crude for anything but the early pong systems > and you wouldn't be able to differentiate between hitting one object or > another, etc.... > > The Atari 8-bit has discrete hardware registers for reading a light pen > (light pens work better than guns for obvious reasons). It does a fairly > rough job on the horizontal ;) The important thing isn't whether or not a > light gun detects light (which will just give you on or off), it is > finding a way for the computer to determine the X and Y coordinates of > where the beam is hitting the TV, and THEN cross referencing this with > your objects. Well, I've always just kinda assumed that you would sequence the targets. I.e. dont draw them every frame. A well designed light gun will have a fairly narrow field of vision, so could be pretty accurate. I don't know how it's implemented in the 2600 (anyone disassembled Sentinel yet? :) ), but I do know that the gun has to be the sensor. CRT's are output only. And if the lightgun has a photodiode or phototransistor rather than a photo- resistor, then it can be fast enough to sense within 20 pixels or so on the 2600... -Chris -- Archives updated once/day at http://www.biglist.com/lists/stella/archives/ Unsubscribing and other info at http://www.biglist.com/lists/stella/stella.html
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