Midi script for VST protoplug for "drone" notes

midi-drone-note.lua

require "include/protoplug"

noteOn = 0

function plugin.processBlock(samples, smax, midiBuf)
  blockEvents = {}
  -- drone note, 72 = C
  local rootNote = 69

  for ev in midiBuf:eachEvent() do
    if ev:isNoteOn() and ev:getNote() ~= rootNote then
      if noteOn > 0 then
        local newEv = midi.Event.noteOff(
          ev:getChannel(),
          rootNote,
          ev:getVel())
        table.insert(blockEvents, newEv)
      end
      local newEv = midi.Event.noteOn(
        ev:getChannel(),
        rootNote,
        ev:getVel())
      table.insert(blockEvents, newEv)
      noteOn = noteOn + 1
    elseif ev:isNoteOff() and ev:getNote() ~= rootNote then
      local newEv = midi.Event.noteOff(
        ev:getChannel(),
        rootNote,
        ev:getVel())
      if noteOn==1 then
        table.insert(blockEvents, newEv)
      end
      noteOn = noteOn - 1
    end
  end

  --midiBuf:clear() --uncomment for just drone note
  if #blockEvents>0 then
    for _,e in ipairs(blockEvents) do
      midiBuf:addEvent(e)
    end
  end
end