If the gun is pointed at the wrong spot on the screen, the sensor will only register black and you lose. How did this work with two ducks? When the game had two ducks on screen, the third frame showed the second white box. Easy peasy. Did you know that the second controller could actually control the duck? In the event of multiple targets, a white block is drawn around each potential target one at a time. This target flashing method helped Nintendo overcome a weakness of older light gun games: cheaters racking up high scores by pointing the gun at a steady light source, like a lamp, and hitting the first target right out of the gate.
BY Matt Soniak. Here's what happens. When playing Duck Hunt you pull the trigger to shoot a duck out of the air. When that trigger is pulled, the TV screen goes entirely black for one frame. The light sensor uses that black screen as a reference point, which helps it account for the wide variety of lighting situations in the rooms where the game is being played.
In the next frame, the area the duck occupied turns white while the rest of the screen remains black. If the light sensor detects light in that second frame, your gun is on target. If the light sensor does not, the dog is going to laugh at you. How does it work? How did the NES, which was far less advanced than modern pointing consoles like the Wii, know where we were aiming? It's a light gun. It has a single light sensor in the tip, which picks up light from the part of the screen it is aimed at.
Given that the CRT TVs used at the time essentially instantaneously displayed the signal sent from the console, this was quite sufficient. I've never used a Zapper myself, but according to the Wikipedia article, it worked as follows: when the trigger is pulled, the console would display a flash of light from the location of each target in sequence.
Whichever flash produced a pulse from the sensor indicated a hit target. Using even finer timing which, again according to the Wikipedia article, the Zapper was not capable of , arbitrary locations on the screen can be identified by detecting the pulses resulting from the sweep of the electron beam across the screen.
All of this is fundamentally dependent on the low-persistence nature of CRTs: each location on the screen emits light only when the input signal passes them as it sweeps out the entire image. This is very different from modern LCD displays, where each individual pixel is a device which changes state slowly! The NES Zapper is a simple photodiode connected to a switch.
A photodiode allows current to pass, but only if there is light present. When you pull the trigger, the following happens in quick succession:. The hit or miss is registered based on if the first check was "it's dark," and the second was "it's light. If there are multiple targets, and the game had to be able to tell which one you hit, the later steps were repeated, with just one of the objects set to white at a time.
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