-- Example 6 - Generating Score

-- Author: Steven Yi <stevenyi@gmail.com>

-- 2013.10.28

--

-- This example continues on from Example 5, rewriting the example using

-- a Class called Note. The note example has its __str__ method implemented

-- to generate a well-formatted Csound SCO note.

--

-- This example also shows how a list of notes could be used multiple times.

-- The first loop through we use the notes as-is, and during the second time

-- we generate the notes again with the same properties except we alter the

-- fifth p-field up 4 semitones.

--

-- Note: Altering a Notes values like this is alright for this example, but

-- it is a destructive edit. Real world code might make copies of Notes or

-- alter the score generation to maintain the original values.

require "luaCsnd6"

function midi2pch(num)

-- Convert MIDI Note Numbers to Csound PCH format

return string.format("%d.%02d", 3 + (num / 12), num % 12)

end

local Note = {}

function Note:new(pfields)

local o = {}

setmetatable(o, self)

self.__index = self

o.pfields = pfields

return o

end

function Note:tostring()

local retVal = {}

for i, v in ipairs(self.pfields) do

if(i == 5) then

retVal[#retVal+1] = midi2pch(v)

else

retVal[#retVal+1] = v

end

end

return "i" .. table.concat(retVal, " ")

end

-- Our Orchestra for our project

local orc = [[

sr=44100

ksmps=32

nchnls=2

0dbfs=1

instr 1

ipch = cps2pch(p5, 12)

kenv linsegr 0, .05, 1, .05, .7, .4, 0

aout vco2 p4 * kenv, ipch

aout moogladder aout, 2000, 0.25

outs aout, aout

endin

]]

local c = luaCsnd6.Csound() -- create an instance of Csound

c:SetOption("-odac") -- Set option for Csound

c:CompileOrc(orc) -- Compile Orchestra from String

local notes = {} --initialize a table to hold lists of values

for i=0, 12 do --populate that table

notes[#notes+1] = Note:new{1, i * .25, .25, 0.5, math.random(60,75)}

end

-- now convert list of Note objects to string

sco = ""

for _,n in pairs(notes) do

-- this implicitly calls the tostring method on the Note Class

sco = sco .. n:tostring() .. "\n"

end

-- generate notes again transposed a Major 3rd up

for _,n in pairs(notes) do

n.pfields[5] = n.pfields[5] + 4

n.pfields[2] = n.pfields[2] + .125

sco = sco .. n:tostring() .. "\n"

end

print(sco)

c:ReadScore(sco) -- Read in Score generated from notes

c:Start() -- When compiling from strings, this call is necessary before doing any performing

-- The following is our main performance loop. We will perform one block of sound at a time

-- and continue to do so while it returns 0, which signifies to keep processing.

while (c:PerformKsmps() == 0) do end

c:Stop()