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A central part of the TXTris concept is that the virtual interacts with the real, when the falling computer projected words drift on the physical cardboard structures placed in front of the projection screen. Here’s some information on how we did that, by making the computer ‘aware’ of the physical obstacles so it could interact with them.

Step 1 - create a cardboard city (or horse, or race car - it’s up to you). Squarish, large, blocky shapes work best with mk I of the system. Attach your city immediately in front of the projection screen.

Step 2 - put the TXTris application into calibration mode. This projects a grid and the mouse pointer over top of the screen. Using the mouse and some simple drawing techniques to mark the grid blocks that are filled by the cardboard objects.

Step 3 - flip out of calibration and into live mode. The application is now aware of where within its projection the physical objects are located.

Now the app starts grabbing live SMS messages sent to our SMS server. Those messages appear one at a time, falling slowly down the screen until the individual letters reach the skyline of our city, and there they sit.

There you have it. That’s how to build a physically aware SMS wall. Well that, a few hundred lines of Processing code and a hand-made cardboard skyline.

You’re on your own with the skyline building (don’t worry, it’s fun), but if you’re interested in the code drop me a line. The TXTris app too full of hacks and kludges to release as open source right now, but I’m happy to share what I learnt in writing it.