We used the visual programming language VVVV which is available for free for non-commercial purposes. Unfortunately it is made for the Windows operating system only (working on Intel-Macs is fine, but limited in some points). For more details please visit vvvv.org
Some words about our patch (this is the VVVV-programme)
Our VVVV-patch consists of several subpatches. If you want to use it for your own project, please download the zip-file below, unzip it and move the subpatches to the appropriate folders on your computer. For the visuals we set images (png-files) as textures for boxes. The boxes themselves are completely transparent, only the textures are displayed.