path: root/intervals.lua

-- interval ear training
--
-- hear two notes;
-- play two notes
--
-- enc2: repeat
-- enc3: skip
--
-- to do:
-- 1) keep a score
-- 2) select scales
-- 3) select base tone
-- 4) key signatures
-- 5) play from input

-- graphics and audio utilities
function midi_to_hz(note)
  local hz = (440 / 32) * (2 ^ ((note - 9) / 12))
  return hz
end

function interval_name(base, interval)
  t = {
    "unison",
    "minor second",
    "major second",
    "minor third",
    "major third",
    "perfect fourth",
    "diminished fifth",
    "perfect fifth",
    "minor sixth",
    "major sixth",
    "minor seventh",
    "major seventh",
    "octave"
  }
  return t[interval - base + 1]
end

function blit(x, y, bitmap, p)
  for i=1,#bitmap do
    for j=1,#bitmap[i] do
      local level = bitmap[i][j]
      if p and p.brightness then
        level = level * p.brightness
      else
        level = level * 10
      end
      if level > 0 then
        screen.level(math.floor(level))
        screen.pixel(x + j, y + i)
        screen.fill()

      end
    end
  end
end

function blit_center(x, y, sprite, p)
  local offset_before = sprite.offset_before or #sprite.data[1] / 2
  local offset_above = sprite.offset_above or #sprite.data / 2
  blit(x - offset_before, y - offset_above, sprite.data, p)
end

local quarter_sprite = {
  data={
    { 0,  0,  0,  0,  1,  0,  0},
    { 0,  0,  0,  0,  1,  0,  0},
    { 0,  0,  0,  0,  1,  0,  0},
    { 0,  0,  0,  0,  1,  0,  0},
    { 0,  0,  0,  0,  1,  0,  0},
    { 0,  0,  0,  0,  1,  0,  0},
    { 0,  1,  1,  1,  1,  0,  0},
    { 1,  1,  1,  1,  1,  0,  0},
    { 0,  1,  1,  1,  0,  0,  0},
  },
  -- metadata to center properly
  offset_before=2,
  offset_above=8
}

local sharp_sprite = {
  data = {
    { 0, 1, 0, 1, 0 },
    { 1, 1, 1, 1, 1 },
    { 0, 1, 0, 1, 0 },
    { 1, 1, 1, 1, 1 },
    { 0, 1, 0, 1, 0 }
  }
}

local flat_sprite = {
  data = {
    { 1, 0, 0, 0},
    { 1, 0, 0, 0},
    { 1, 1, 1, 0},
    { 1, 0, 1, 0},
    { 1, 1, 0, 0}
  }
}
-- parameters:
-- p.y: offset from the top
-- p.margin: distance from the side (since it's all centered)
-- p.notes: all quarter notes for now
function staff (p)
  local x_start = p.margin;
  local x_end = 128 - p.margin
  local width = 128 - p.margin * 2

  screen.level(1)
  for i=0,4 do
    for j=x_start,x_end do
      screen.pixel(j, p.y + 5 * i)
    end
  end
  screen.fill()

  for i=1,#p.notes do
    -- adjust for lines drawn
    local bottom_y = p.y + 20
    -- offset for this particular note
    local y = math.ceil(bottom_y - 2.5 * p.notes[i].place)

    -- evenly distribute along the x-axis
    local total_x = 128 - p.margin * 2
    local each_x = total_x / #p.notes
    local x = x_start + each_x * (i - 1) + each_x / 2

    -- draw the broken staff line, if it's out of range
    if y > bottom_y or y < p.y then
      screen.level(1) -- todo p.brightness
      screen.move(x - quarter_sprite.offset_before - 1, y + 1)
      screen.line(x + #quarter_sprite.data[1] - 1, y + 1)
      screen.stroke()
    end

    if p.notes[i].accidental > 0 then
      blit_center(x - 6, y, sharp_sprite, p.notes[i])
    elseif p.notes[i].accidental < 0 then
      blit_center(x - 6, y, flat_sprite, p.notes[i])
    end

    -- draw the note
    blit_center(x, y, quarter_sprite, p.notes[i])
  end
end

-- todo could probably do this more nicely
function c_major_treble(midi_note)
  local scale = {
    -- c / c#
    [60]={place=-2, accidental=0},
    [61]={place=-2, accidental=1},
    -- d / d#
    [62]={place=-1, accidental=0},
    [63]={place=-1, accidental=1},
    -- e 
    [64]={place=0, accidental=0},
    -- f / f#
    [65]={place=1, accidental=0},
    [66]={place=1, accidental=1},
    -- g / g#
    [67]={place=2, accidental=0},
    [68]={place=2, accidental=1},
    -- a / a#
    [69]={place=3, accidental=0},
    [70]={place=3, accidental=1},
    -- b
    [71]={place=4, accidental=0},
    -- c
    [72]={place=5, accidental=0},
  }
  return scale[midi_note]
end

-- little mode library...
-- a mode is a thing with fields for enc, redraw, and key
-- it can edit the state
function state_call(state, name, args)
  if state.stack[#state.stack] then
    local fn = state.stack[#state.stack][name]
    if fn then
      local ret = fn(table.unpack(args or {}))
      if ret then
        ret(state)
      end
    end
  else
    print("empty state?")
  end
end

function state_init(state)
  -- destroy old timer, create a new one.
  -- we need to do this because e.g. if we transition
  -- to the next screen halfway between 1 and 2, then we'll
  -- pause for half a second less than we ought to.
  if state.timer then
    state.timer:stop()
    metro.free(state.timer.id)
  end
  state.timer = metro.init()
  state.timer.time = state.tick_interval or 1.0
  state.timer.event = function(t)
    state_call(state, "tick", {t})
  end
  state_call(state, "init")
  state.timer:start()
end

function state_redraw(state)
  state_call(state, "redraw")
end

function pop(state)
  table.remove(state.stack)
  state_init(state)
end

function pop_n(n)
  return function (state)
    if state.timer then
      state.timer:stop()
    end
    for i=1,n,1 do
      table.remove(state.stack)
    end
    state_init(state)
  end
end

function replace(modes)
  return function (state)
    top = table.remove(state.stack)
    push(modes)(state)
  end
end

function push(modes)
  return function (state)
    for i=1,#modes do
      table.insert(state.stack, modes[i])
    end
    state_init(state)
  end
end

-- end mode library

engine.name = 'PolyPerc'
function play(hz)
  engine.hz(hz)
end


function message (msgs, tick_fn, midi_fn)
  return {
    init = function ()
      return state_redraw
    end,
    redraw=function ()
      screen.clear()
      local total_height = 10 * #msgs
      local y = (64 - total_height) / 2
      local x = 64
      for i=1,#msgs do
        screen.move(x, y + 10 * (i - 1) + 5)
        screen.text_center(msgs[i])
      end
      screen.update()
    end,
    key=function (n, x)
      if n == 3 and x == 0 then
        return pop
      end
    end,
    tick=function(t)
      if tick_fn then
        return tick_fn(t)
      end
    end,
    midi=function(ev)
      if midi_fn then
        return midi_fn(ev)
      end
    end
  }
end

function correct_guess(known, guess)
  return {
    init=function ()
      return state_redraw
    end,
    redraw=function()
      local known_note = c_major_treble(known)
      known_note.brightness = 10
      local guess_note = c_major_treble(guess)
      guess_note.brightness = 10
      staff({y=20, margin=5, notes={
        known_note, guess_note
      }})
      screen.move(64, 10)
      screen.text_center(interval_name(known, guess))
      screen.update()
    end,
    key=function(n, x)
      if n == 3 and x == 0 then
        return pop
      end
    end,
    tick = function()
      return pop
    end
  }
end

function play_and_wait_3 (known, guess)
  return {
    init=function ()
      return state_redraw
    end,
    redraw=function()
      screen.clear()
      local known_note = c_major_treble(known)
      known_note.brightness = 10
      staff({y=20, margin=5, notes={
        known_note,
        {place=0,accidental=0, brightness=0}
      }})
      screen.update()
    end,
    key=function(n, x)
      if n == 3 and x == 0 then
        return pop
      end
    end,
    midi=function(ev)
      if ev.type == "note_on" and ev.note == guess then
        return pop
      end
    end
  }
end

function play_and_wait_2 (known, guess)
  return {
    init=function ()
      play(midi_to_hz(guess))
      return state_redraw
    end,
    redraw=function()
      screen.clear()
      local known_note = c_major_treble(known)
      known_note.brightness = 5
      staff({y=20, margin=5, notes={
        known_note,
        {place=0,accidental=0, brightness=0}
      }})
      screen.update()
    end,
    key=function(n, x)
      -- forward button
      if n == 3 and x == 0 then
        return pop_n(2)
      end
      -- back button
      if n == 2 and x == 0 then
        return push({play_and_wait_1(known, guess)})
      end
    end,
    midi=function(ev)
      if ev.type == "note_on" and ev.note == known then
        return pop
      end
    end
  }
end

function play_and_wait_1 (midi_note)
  complete = nil
  return {
    init=function ()
      play(midi_to_hz(midi_note))
      return state_redraw
    end,
    redraw=function()
      screen.clear()
      local known_note = c_major_treble(midi_note)
      known_note.brightness = 5
      staff({y=20, margin=5, notes={
        known_note,
        {place=0,accidental=0, brightness=0}
      }})
      screen.update()
    end,
    tick=function()
      return pop
    end,
    key=function(n, x)
      -- forward button
      if n == 3 and x == 0 then
        return pop_n(3)
      end
      -- back button
      if n == 2 and x == 0 then
        print("back on 1")
        return replace({play_and_wait_1(midi_note)})
      end
    end,
  }
end

function choose_interval ()
  return {
    init=function ()

      local guess = math.random(60, 72)
      return push({
        correct_guess(60, guess),
        play_and_wait_3(60, guess),
        play_and_wait_2(60, guess),
        play_and_wait_1(60)
      })
    end
  }
end

-- drawing, state, etc
intervals_state = {
  stack = {
    choose_interval(),
    message({
      "first I'll play middle c.",
      "then a random major interval.",
      "play both notes back",
      "as best as you can"},
    function (t)
      if t > 2 then
        return pop
      end
    end),
    message({"yay."},
    function ()
      return pop
    end),
    message({
      "plug in a midi keyboard",
      "and give me a middle c."
    },
    nil,
    function (ev)
      if ev.type == "note_on" and ev.note == 60 then
        return pop
      end
    end)
  },
}

function init()
  play(midi_to_hz(60))
  -- initialize midi
  m = midi.connect()
  m.event = function (a)
    b = midi.to_msg(a)
    -- monitor
    if b.type == "note_on" then
      play(midi_to_hz(b.note))
    end
    state_call(intervals_state, "midi", {b})
  end
end

function cleanup()
  intervals_state.timer:stop()
end

function redraw()
  screen.clear()
  screen.aa(0)
  screen.line_width(1)

  state_call(intervals_state, "redraw")
end

function key(n, x)
  state_call(intervals_state, "key", {n, x})
end