Instrumentation - A .lua file that will help you create software instruments.

init.lua

--
-- instrumentation
--
-- The MIT License (MIT)
--
-- Copyright (c) 2014, DesertRock
--
-- Permission is hereby granted, free of charge, to any person obtaining a copy
-- of this software and associated documentation files (the "Software"), to deal
-- in the Software without restriction, including without limitation the rights
-- to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
-- copies of the Software, and to permit persons to whom the Software is
-- furnished to do so, subject to the following conditions:
--
-- The above copyright notice and this permission notice shall be included in
-- all copies or substantial portions of the Software.
--
-- THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
-- IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
-- FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
-- AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
-- LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
-- OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
-- THE SOFTWARE.
--
-- Notice that this license does not apply to the dependancy on the music.lua and
-- classic.lua. There is also a hidden depenancy on slam.lua. This project should
-- be included by the main application.
-- These libraries can be found here:
-- classic.lua - https://github.com/rxi/classic
-- music.lua - https://github.com/WetDesertRock/music.lua
-- slam.lua - https://github.com/vrld/slam
--
-- To use, require this file.
-- Example of usage:
--
-- -- Require the slam and the file
-- require("libraries/slam")
-- Instrument = require('instrument)
--
-- -- Create the instrument
-- ins = Instrument.Instrument()
--
-- --  Load samples from folder. Samples must be labled by their midi note name in
-- -- the folder. Example folder structure:
-- --   sounds/
-- --     mysynth/
-- --       60.wav
-- --       48.wav
-- --       72.wav
-- -- This command will load those sounds. The final slash is necessary.
-- ins:readFromFolder("sounds/mysynth/")
-- 
-- -- You can also load custom samples by using the method :setSource(note,src)
-- -- Note is the midi note number that corrosponds to the sound source src.
-- ins:setSource(60, love.audio.newSource("sounds/mysynth/60.wav", 'static')
--
-- -- Play sounds:
-- note = ins:play(24)
-- note:setVolume(0.5)
--

local Object = require(... .. ".classic")
local mus = require(... .. ".music")

local tracks = {}

local function tablelength(t)
    local c = 0
    for _,_ in pairs(t) do c = c+1 end
    return c
end

tracks.Instrument = Object:extend()

function tracks.Instrument:new(soundfolder,temperment)
    if temperment == nil then
        self.temperment = "equal"
    else
        self.temperment = temperment
    end
    self.sources = {}
end

function tracks.Instrument:setSource(note,src)
    self.sources[note] = src
end

function tracks.Instrument:readFromFolder(soundfolder)
    local files = love.filesystem.getDirectoryItems(soundfolder)
    for _,f in pairs(files) do
        local note = tonumber(f:match("(%d*)"))
        if note ~= nil then
            local src = love.audio.newSource(soundfolder..f, 'static')
            self:setSource(note,src)
        end
    end
end

function tracks.Instrument:play(note)
    assert(tablelength(self.sources)~=0,"Instrument does not have any sources!")
    local mindist = 255 -- There cannot be anything greater than this, right?
    local minkey = nil
    for n,snd in pairs(self.sources) do
        local d = math.abs(note-n)
        if d < mindist then
            mindist = d
            minkey = n
        end
    end

    local pr = mus.pitchRatio(note-minkey,self.temperment)
    local snd = self.sources[minkey]:play()
    snd:setPitch(pr)
    return snd
end

return tracks