A Logic Pro X Scripter patch to map note pitch to panning

logic-scripter-pitch-to-pan.js

function mapLinear(value, inMin, inMax, outMin, outMax) {
    if (value <= inMin) {
        return outMin;
    }
    if (value >= inMax) {
        return outMax;
    }

    const inRange = inMax - inMin;
    const valueNorm = (value - inMin) / inRange;

    const outRange = outMax - outMin;
    const scaled = outMin + valueNorm * outRange;

    return scaled;
}

function HandleMIDI(event) {
    if (event instanceof NoteOn) {
        // define the note range you want to map
        // any note below noteMin_midi will have the same pan value as noteMin_midi
        // any note above noteMax_midi will have the same pan value as noteMax_midi
        const noteMin_midi = 21; // A0 on piano
        const noteMax_midi = 108; // C8 on piano

        // define the panning range
        // 0.0 is full left
        // 1.0 is full right
        const panMin_n = 0.1; // lowest note will be almost completely left
        const panMax_n = 0.9; // highest note will be almost completely right

        // map the pitch range to panning range
        const panValue_n = mapLinear(event.pitch, noteMin_midi, noteMax_midi, panMin_n, panMax_n);
        const panEvent = new ControlChange();
        panEvent.number = 10; // 10 is pan
        panEvent.value = panValue_n * 127; // multiply by 127 to get back to MIDI range
        panEvent.send();
    }

    // send the original event
    event.send();
}