Hookpad translates incoming midi messages to the corresponding notes or chords in the key of your project. So for example if you’re in the key of C Major and you input G4, it would add a scale degree 5 in the melody region or a V chord in the chord region.
We don’t currently have a setting that allows midi messages to enter in scale degrees directly by number, although that’s an interesting use case that we hadn’t considered before. To do this, we would do something like map the C major scale to scale degrees 1 through 7, regardless of the key, but also respecting the octave of the input.
For chords, if you could program your Launchpad to send multiple midi messages simultaneously then that would work. Right now Hookpad tries to infer the chord from the inputted notes, and there’s always a combination of notes that will trigger a particular chord, e.g.,in C Major, C+E+G triggers a I chord, B + G + D triggers at V6 chord, etc.
Right now, Hookpad adds a note or chord depending on where your cursor is, so we would have to have a special mode if you wanted to play Hookpad like an instrument, perhaps having isolated midi messages played as notes and multiple simultaneous messages played as chords.