Multitouch on a Mac without a Touchscreen

fingerpinger

As you may have noticed it’s been a little quiet around here lately. The reason for this is that since the end of 2013 I have been keeping myself busy with a studio remodel (more on that later) followed by concentrating on preparations for a performance (I’m pleased to announce) at Echofluxx 14 in Prague, May 2014. Here’s a quick note about Echofluxx 13 from their site:

The Echofluxx 13 is a festival of new media, visual art, and experimental music produced by Efemera of Prague with Anja Kaufmann and Dan Senn, co-directors. In cooperation with Sylva Smejkalová and early reflections, the Prague music school (HAMU), and Academy of Fine Arts (AVU), Echofluxx 13 will present international and Czech presenters in a five-day festival at the Tracfačka Arena in Prague, Kurta Konráda 1, Prague 9, May 7-11, 2013. For more information contact: info@echofluxx.org

I’ll discuss more details about this upcoming performance in another post. For now I would like to bring attention to the possibility of using the Mac trackpad and/or Apple’s Magic Trackpad for multitouch. My performance at Echofluxx involves using custom built software to loop granular audiovisual media. This idea evolved from projects in the past that used a 32″ touchscreen. This time the media will be projected, so I naturally decided to use the iPad as the controller. I built the project using Cycling ’74 Max and MIRA, which was very convenient, but I couldn’t get over the latency using the iPad over WiFi for multitouch controls.

I decided that the most convenient alternative would be to use the trackpad on the Mac laptop. Max has an object called “mousestate” that polls button-status and cursor-position information from the default pointer device. However, it is not designed to take advantage of multitouch data. This is where Fingerpinger comes in. Fingerpinger was able to detect ten independent touch points (perhaps more but I was out of fingers) on the built in trackpad on my MacBook Pro. Which begs the question; how did I take that screenshot?

Ten touchpoints on such a small surface is probably impractical, but I only need two; one for X-Y data and a second one for volume. Most importantly I wanted the audiovisual content to be activated simply by touching the trackpad rather than having to click or hold down a key. Fortunately Fingerpinger has a state value for each touchpoint that I was able to use to activate on touch and release. The latency is hardly noticeable compared to an iPad over WiFi, and I have also simplified my setup meaning I can travel with less equipment and rely on fewer technologies. I still like the idea of using an iPad for multitouch controls, mostly because of the opportunities for visual feedback. But for this particular application Fingerpinger is a great solution.

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About John CS Keston

John CS Keston is an award winning transdisciplinary artist reimagining how music, video art, and computer science intersect. His work both questions and embraces his backgrounds in music technology, software development, and improvisation leading him toward unconventional compositions that convey a spirit of discovery and exploration through the use of graphic scores, chance and generative techniques, analog and digital synthesis, experimental sound design, signal processing, and acoustic piano. Performers are empowered to use their phonomnesis, or sonic imaginations, while contributing to his collaborative work. Originally from the United Kingdom, John currently resides in Minneapolis, Minnesota where he is a professor of Digital Media Arts at the University of St Thomas. He founded the sound design resource, AudioCookbook.org, where you will find articles and documentation about his projects and research. John has spoken, performed, or exhibited original work at New Interfaces for Musical Expression (NIME 2022), the International Computer Music Conference (ICMC 2022), the International Digital Media Arts Conference (iDMAa 2022), International Sound in Science Technology and the Arts (ISSTA 2017-2019), Northern Spark (2011-2017), the Weisman Art Museum, the Montreal Jazz Festival, the Walker Art Center, the Minnesota Institute of Art, the Eyeo Festival, INST-INT, Echofluxx (Prague), and Moogfest. He produced and performed in the piece Instant Cinema: Teleportation Platform X, a featured project at Northern Spark 2013. He composed and performed the music for In Habit: Life in Patterns (2012) and Words to Dead Lips (2011) in collaboration with the dance company Aniccha Arts. In 2017 he was commissioned by the Walker Art Center to compose music for former Merce Cunningham dancers during the Common Time performance series. His music appears in The Jeffrey Dahmer Files (2012) and he composed the music for the short Familiar Pavement (2015). He has appeared on more than a dozen albums including two solo albums on UnearthedMusic.com.

One thought on “Multitouch on a Mac without a Touchscreen

  1. Yes I’m commenting on my own post… In any case, here’s how I made the screenshot. In terminal type the following:

    screencapture -T 10 myscreenshot.png

    You’ll have 10 seconds to prepare the screen before the screenshot is taken.

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