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The light gun is a fondly recalled (though often financially unprofitable for the makers) control device for [arcade games]? and console video games. The device is modeled after some sort of weapon, usually a pistol and is used for targeting characters on the screen. The most popular example of this would be Nintendo's Zapper gun for the Nintendo Entertainment System, though there are light guns for Sony PlayStation, Sega Dreamcast, and undoubtedly several other console and arcade systems. It is similar in principle to the [Light pen]?. |
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The light gun is a fondly recalled (though often financially unprofitable for the makers) control device for [arcade games]? and console video games. The device is modeled after some sort of weapon, usually a pistol or bazooka, and is used for targeting characters on the screen. The most popular example of this would be Nintendo's Zapper gun for the Nintendo Entertainment System, though there are light guns for Sony PlayStation, Sega Dreamcast, and undoubtedly several other console and arcade systems. It is similar in principle to the [Light pen]?. |
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Essentially the diode tells the computer whether or not you hit something, and the sequence of the drawing of the squares tell the computer which target you hit after 1 + ceil(log2(n)) refreshes (one to determine if any target at all was hit and ceil(log2(n)) to do a binary search for the object that was hit). An interesting side effect of this is that often one can point the gun at a light bulb, pull the trigger and hit the first target every time. The second method, used by the Super Nintendo Entertainment System's Super Scope and the EGA?'s light pen is pretty elaborate, but more accurate. After the screen blacks, the screen is then painted white. The trick to this method relies on the nature of the [cathode ray electron tube]? inside the video monitor. The screen is drawn by a scanning electron beam that essentially travels across the screen starting at the top until it hits the end, and then moves down to update the next line. this is done repeatedly until the entire screen is drawn, and appears instantaneous to the human eye as it is done very quickly. The computer simply times how long it takes the electron beam to excite the phosphor? at the location the gun is pointed at, and calculates the targeted position based on the monitor's horizontal refresh rate (the fixed amount of time it takes the beam to get from the left to right side of the screen), perhaps in conjunction with the display adapter. |
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Essentially the diode tells the computer whether or not you hit something, and for n objects, the sequence of the drawing of the targets tell the computer which target you hit after 1 + ceil(log2(n)) refreshes (one to determine if any target at all was hit and ceil(log2(n)) to do a binary search for the object that was hit). An interesting side effect of this is that on poorly designed games, often a player can point the gun at a light bulb, pull the trigger and hit the first target every time. Better games account for this by not using the first target for anything. The second method, used by the Super Nintendo Entertainment System's Super Scope and the EGA?'s light pen, is more elaborate but more accurate. The trick to this method relies on the nature of the cathode ray tube inside the video monitor; it does not work with LCD projectors. The screen is drawn by a scanning electron beam that essentially travels across the screen starting at the top until it hits the end, and then moves down to update the next line. This is done repeatedly until the entire screen is drawn, and appears instantaneous to the human eye as it is done very quickly. When the player pulls the trigger, the game brightens the entire screen for a split second, and the computer (often assisted by the display circuitry) times how long it takes the electron beam to excite the phosphor? at the location the gun is pointed at, and calculates the targeted position based on the monitor's horizontal refresh rate (the fixed amount of time it takes the beam to get from the left to right side of the screen). |
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However, many guns of this type (including the Super Scope) ignore red light, as red phosphors have a much slower rate of decay than green or blue phosphors. |
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Games that used more than one gun could have both diodes connect to the same internal register and then assign a target to one gun or the other by which trigger was pulled. As stated before, people love the light gun. It is very popular for arcade games, but has never caught on in the home video game console market. This is most likely because it was often a peripheral that had to be purchased separately. Consumers rarely ever buy even a second controller for their system, let alone a special-purpose and often pricey device, and so games centered around the gun were often found to be unprofitable. Ironically, the lack of games is a significant factor as well in people deciding not to buy the peripheral. |
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A game that uses more than one gun reads both triggers continuously and then, when one player pulls a gun's trigger, the game poll that gun's diode until it knows which object was hit. |
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As stated before, people love the light gun. It is very popular for arcade games, but has never caught on in the home video game console market. This is most likely because it was often a peripheral that had to be purchased separately. Consumers rarely ever buy more than one extra controller for their system, let alone a special-purpose and often pricey device, and so games centered around the gun were often found to be unprofitable and later re-tooled to use a standard joypad or especially a computer mouse. Ironically, the lack of games is a significant factor as well in people deciding not to buy the peripheral. |
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