miz1q2w3e on 11 September 2010
Some TVs actually use the same principle you mentioned for their glasses-less 3D, they track a person's eye so that they don't have to have a fixed position in terms of the TV
This however is not necessary in the 3DS because unlike a TV where you can sit anywhere in the room, with a handheld device you're usually holding it the same way all the time which is in front of your face (think about it, why would you hold it on an angle away from yourself on purpose?) - reminds me of LCD screens and how they have a limit to what angle you can view them on (although it's not the same reasoning behind it)
what you mentioned is "eye tracking" : http://en.wikipedia.org/wiki/Autostereoscopy
hope that helps :)
