For our prototype we chose to use a ultrasounds sensor. This sensor calculate the distance of a user.
Writing the code was very difficult, even if the logic of the prototype is not difficult.
We used Processing, we recalled the serial ports of the computer, and recalled the next data alone from the door entrusted at the sensor.
There is a file .txt to download to see our code.
Tree of Life code
An another file to download to see the explanation of our code.
Explanation code