3D on Android (Geekcon 2011)

I’ve recently participated in Geekcon 2011. It is similar to Garage Geeks but the thing is that people actually build stuff during the two and a half days of staying there.
My friends, Ofer Gadish and Gil Shai from Acceloweb and I worked on displaying stereoscopic 3-D images on an Android device. Those were exciting three days of sleeping very little, coding a lot, soldering, drinking beer and having a lot of fun.

When we initially discussed the idea we thought about using 3-D glasses controlled by Bluetooth but we realized that in the short time we had we would probably not be able to study the control protocol and also figure out how we directly control the Bluetooth transmitter of the mobile device, if it is at all possible to do it on such a low level from a user application.

Instead we have chosen to control the glasses through the audio jack output of the mobile phone. We found another pair of glasses controlled using quite an old VESA standard. The glasses are supplied with 3-pin mini-DIN receptacle. The idea is very simple: high voltage means logical “1” means opening the left eye and low voltage means logical “0” means opening the right eye.

To supply ground, +5V and an accurate square wave synchronization signal to the glasses we’ve done some soldering and connected the mini-DIN to an Arduino, that was in turn receiving the output from the mobile’s audio jack.

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The Android software was a bit of a mess, reaching a switching rate of 60 Hz wasn’t very simple considering the slow performance which I don’t exactly know what to attribute to, whether it is a slow refresh rate of the display or the technique we used to draw the images (although we accessed the canvas directly, bypassing any higher level APIs for displaying a picture). On Saturday afternoon we had it running, with some glitches occurring every couple of seconds, but giving some feeling of 3-D depth. Or was it our exhausted imagination after not sleeping too much during this crazy and awesome weekend?

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