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Lights Guns And Projectors

Discussion in 'Nintendo Forums' started by Chaos Star, Sep 17, 2003.

  1. Chaos Star

    Chaos Star
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    Is it possible to get a light gun to work with a projector ?

    :hiya:
     
  2. Pulsar

    Pulsar
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    Nope, but I would love to be proved wrong.
     
  3. Chaos Star

    Chaos Star
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    Same hear, I was 99.9% sure it wasnt currently possible. Its a damn shame as it would be awesome to play house of the dead etc. on a huge screen.
     
  4. SeaneyC

    SeaneyC
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    I'd imagine that a CRT projector hooked up in the most basic way (running at 576i PAL) would work with a light gun.

    And i also believe that there are 100Hz light guns available now, i'm not sure how they work.
     
  5. Taz

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    To create this effect, the gun contains a photodiode (or a phototransistor) in the barrel. The photodiode is able to sense light coming from the screen. The gun also contains a trigger switch. The output of the photodiode and the switch are fed to the computer controlling the game.

    At the same time, the computer is getting signals from the screen driver electronics. If you have read How Television Works, you know about the horizontal retrace and vertical retrace signals used to align the picture on the screen. The screen driver electronics send pulses to the computer at the start of the horizontal and vertical retrace signals, so the computer knows where on the screen the electron beam is located during each frame.

    The computer normally uses one of two different techniques to figure out whether or not the gun is pointed at the target when the user pulls the trigger:

    The computer blanks the screen and then paints just the target object white. If the photodiode senses darkness after one vertical retrace signal and then light after the next, the computer assumes that the gun is pointed at the target and scores a hit.

    The computer blanks the screen and then paints the entire screen white. It takes time for the electron beam to trace the entire screen while painting it white. By comparing the signal coming from the photodiode with the horizontal and vertical retrace signals, the computer can detect where the electron beam is on the screen when the photodiode first senses its light. The computer counts the number of microseconds that pass between the time the horizontal and vertical retrace signals start and the time the photodiode first senses light. The number of microseconds tells the computer exactly where on the screen the gun is pointing. If the calculated position and the position of the target match, the computer scores a hit.



    :D
     
  6. Mr.D

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    And if there is any delay introduced to the video signal from say a scaler or deinterlacer or 100Hz or digitally sampling TVs the gun won't work.

    Numerous mention has been made of 100Hz capable guns but not one person has reported them working...plenty have reported them not working however.
     
  7. Chaos Star

    Chaos Star
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    You can but 100HZ guns for the XBOX, could one of these possibly work with a Panasonic PT 100, or would this still not do the job. It cant be that hard to design a gun that would work as the arcade has light gun shooters with huge screens...
     
  8. NeilMcRae

    NeilMcRae
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    All of which have CRT displays.

    Neil.
     
  9. Mr.D

    Mr.D
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    Nope . I've not seen one report of them working reliably with 100Hz TVs.
    They most definitely will not work with a panasonic ae100 because of the deinterlacing and scaling stages.

    I doubt there ever will be a lightgun that uses the normal principles that will work on these type of displays. Even if they managed to compensate for the delay introduced by the sampling stages you've got no guarantee that the delay will remain consistent across models or even a single unit..

    We might see large screen guns but they won't work on the same principles and I suspect you'd need a different type of console: ie it won't happen for the PS2 or Xbox.
     
  10. Taz

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  11. hencole

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    I've never managed to get any light gun to work on my CRT projector.:(
     
  12. Taz

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    Im not surprised. ;)
     

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