We were discussing video games with a friend some time ago and ended up reflecting on the old duck hunt nintendo game which, if you don't remember, let you shoot ducks on your tv screen with a video gun, plugged in to your console.

Well that seems something fairly common those days with the likes of touch screens, nintendo wiis etc innundating the market but how on earth did they manage to achieve this technicality about 20 years ago.

How does the console know that the video gun is aiming at the duck when you pull the trigger, and not somewhere else?

Well a little bit of research gave me the solution and I thought I would share it here as well as I'm sure this is an existential problem for lots of use, or not :-)

Basically the gun contains a photodiode which is able to detect the light coming from the screen. When the trigger is pressed, the screen is quickly reset and redrawn from scratch in white line by line. The console is able to figure out how long it took before the colour hits the sensor and therefore where exactly the gun is pointing at on the screen. That's the first way of doing it, the second one being that only the target is redrawn.

In both cases it seems to work perfectly, and I think this is a pretty good trick. Also in contrary to all beliefs, fhe gun is not firing at anything but the TV is in fact firing at the gun!

For more information read on the howStuffWorks website to understand. The page also includes a link to the patent nintendo filled in 1989 for that technology.

Labels: old stuff, old technology, video game