Well just a cursory scan of this code seems to suggest it just initializes the MIDI channel and then
sends the current MIDI note that is computed from the pitch using current volume translated to MIDI Velocity:
sendNoteOn (MIDI Note Number, MIDI Velocity, MIDI Channel)
and then if the MIDI NOTE changes, it sends a note off for the current MIDI note
sendNoteOff (MIDI Note Number, MIDI Velocity, MIDI Channel)
then makes the current note the last note and just repeat the process. Not much else I see in the main sketch.
So basically its just "quantizing" pitch to MIDI notes and playing them as notes change.
This in and of itself is not going to be very useful - kind of like setting a Theremini into fully pitch corrected chromatic mode. However the MIDI library that is part of this distribution does contain routines to send pitch bend, program change, control change, aftertouch, sysex, etc., so I assume that its up to users to add code to the program to perform more sophisticated MIDI processing to their liking. Exactly what that should be however, I'm not sure yet. I might send volume translated as a CC that would be sent maybe based on some interrupt or every so often through the main loop. And maybe send pitch bend with that based on the current pitch offset from the current note. Note sure. Will be fun to experiment there later.
Well - now its time to actually build the darned thing. I ordered the knob version as well. I'll post back here when I get things all working.