[pitpank]

Ok, I see. I use p5.js to handle input, and I've just read this in the reference: "The touches[] array is not supported on Safari and IE on touch-based desktops (laptops)." Is that your case?

That link you shared is amazing. I've just visited David Li's website and his work is so cool.

But I don't think I need a smart algorithm to harmonize a melody. In the case of my "diatonic chords chart", I already know what notes to put in the Harmonic table. My voicing concerns are simply about the octave to use and the position in the hex lattice. The voicing itself is constructed out of stacking thirds, roughly speaking.

By the way, I've already added this feature following your advice: the last pressed chord button will be selected in the hex lattice.