Love2d piano

local piano = {}
piano.freq = {
	['C']  = 32.703,
	['C#'] = 34.648,
	['D']  = 36.708,
	['D#'] = 38.891,
	['E']  = 41.203,
	['F']  = 43.654,
	['F#'] = 46.249,
	['G']  = 48.999,
	['G#'] = 51.913,
	['A']  = 55,
	['A#'] = 58.27,
	['B']  = 61.735,
}

function piano:getFrequency(note, octave)
	local freq = self.freq[note:upper()]
	if not freq then return end
	return freq * 2 ^ ((octave or 3) - 1)
end

local function Snusmumriken(freq, ampl, rate)
	local sin = math.sin
	local tau = math.pi * 2
	local freq = freq or 400
	local ampl = ampl or 1
	local rate = rate or 44100
	local dt   = 1/rate

	local time = 0
	return function(fr)
		time = time + (fr or freq) * dt
		return sin(tau * time) * ampl
	end
end

piano.sin = Snusmumriken()

piano.soundData = false

function piano:play(note)
	local octave = 4
	local samples = 441000

	local freq = self:getFrequency(note, octave)
	if not freq then return end


	local data = love.sound.newSoundData(samples, _, 8, 1)

	for i = 1, samples - 1 do
		local snus2 = .4
		data:setSample(i, self.sin(freq) * snus2)
	end

	self.soundData = data

	local source = love.audio.newSource(data)
	print('Play!', note)

	source:play()
end

function love.keypressed(key)
	if love.keyboard.isDown('lshift', 'rshift') then
		key = key..'#'
	end
	piano:play(key)
end


function love.draw()
	local data = piano.soundData
	if not data then return end

	local w, h = love.graphics.getDimensions()


	local count = data:getSampleCount()
	local function graph(i)
		return data:getSample(math.floor(i*count/w))
	end


	local half = 0.2
	love.graphics.line(0, h*half, w, h*half)

	for i = 1, w-1 do
		local x, y = i-1, h*(half + graph(i-1)*half)
		local x2, y2 = i, h*(half + graph(i)*half)

		love.graphics.line(x, y, x2, y2)
	end
end