Wiggle your Hips to Propel the Jellyfish

You can teach Houdini a gesture, and then repeat the gesture along with the beat of the music. A gesture in CHOPs is any set of channels that gets recorded over a frame range. This is a technique that was developed after the Interactive Dance Club. At the IDC, proximity detectors produced midi 0 when the player's hips were to the left, and MIDI 1 when they were to the right. We later replaced the proximity detector with a MIDI slider box.

You can use the Record CHOP to record its incoming channels, whether the channels are coming from a MIDI device or from any other part of Houdini. But the new Gesture CHOP goes further. You hold a button (like from the Keyboard CHOP) that says "I'm recording something now" and let the button go approximately when you are finished recording. The Gesture CHOP extends or shrinks the recording slightly to match exactly a multiple of the beats, represented as ramps in another channel. The ramps are generated from CHOPs like the Beat CHOP.

So any imperfection in the start or stop time of the recording are adjusted by the Gesture CHOP to match the beats, and it also blends the end of the cycle to the start of the cycle.

In the network here, fetch_s1 gets the first slider of a MIDI slider box (Peavey 1600), which is the thing you want to record. A 2/10 second filter is applied to the slider data to smooth it a bit. fetch_b1 gets the first button, and is used to tell the Gesture CHOP "I'm recording".  fetchramp gets the output of the Beat CHOP and tells the Gesture CHOP when the beats are. The remaining CHOPs is just channel naming and recording the time-history for the graph.

The graph contains the beat ramps, plus the results of beat-matched gesture. The outcome is the capture of a 4-bar gesture and the exact repeating of it after the capture. The effect ripples down the length of the jellyfish.

In another network, the speed (Slope CHOP) of the MIDI slider affects the thrusting forward of the jellyfish. SOPs and CHOPs are used to time-delay the ripple going down the length of the tentacles of the jellyfish.