From CCRMA Wiki
This instrument uses the slorkian fret-based mapping to trigger notes. It has been modified to allow polyphony.
How to Play
Pressing alphabetical keys triggers notes. Releasing them releases notes.
Moving the trackpad along the x-axis performs a filter sweep with a moderately high resonance.
Moving the trackpad along the y-axis detunes the sound's multiple oscillators from one another.
Pressing any of the digit keys 0-9 selects a different amplitude envelope. These envelope settings are arranged logically so that towards digit 1, sounds are more percussive, while towards digits 9 (and 0), sounds are pad-like.
Here is the chuck file. Note that you may use a mouse rather than the trackpad to give the instrument a different feel.