conductive-base-0.2: Sound/Conductive/IOI.hs

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-- IOI.hs
-- created: Fri Oct  1 23:21:25 JST 2010

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-- | This module contains functions related to IOI functions and IOI lists.

module Sound.Conductive.IOI where

import Control.Concurrent.MVar
import Data.List
import Data.List.Utils
import Data.Maybe
import Sound.Conductive.ConductiveBaseData
import Sound.Conductive.MusicalEnvironment
import Sound.Conductive.MusicalTime
import Sound.Conductive.Player

-- | Creates an infinite length list from a start time and a finite list of relative time deltas

makeIOIList :: (Num a) => a -> [a] -> [a]
makeIOIList start source = deltasToAbsolutes start $ cycle source

-- | An IOI function which gets an IOI from an IOI list

-- The problem in this function is the error that accumulates from using doubles;
-- the use of minDiff below solves this problem, but it's an ugly hack, I feel.

iOIFromList
  :: MVar MusicalEnvironment -> Player -> String -> IO Double
iOIFromList e p m = let
    minDiff = 0.1
    start = playerStartingBeat p
    b = playerBeat p
    nextBeat currentBeat iOIList = let
        nextTwoBeats = take 2 $ dropWhile (<= currentBeat) iOIList
        in if ((head nextTwoBeats) - currentBeat) < minDiff
                then (nextTwoBeats!!1)
                else (head nextTwoBeats)
    in do   il <- getIOIList e m
            return $ nextBeat b il
            

-- | Creates an IOI list, adds it to the environment, and adds a lookup function for it to the MusicalEnvironment.

newIOIFunctionAndIOIList
  :: MVar MusicalEnvironment
     -> String
     -> Double
     -> [Double]
     -> IO MusicalEnvironment
newIOIFunctionAndIOIList env name startingBeat deltas = let
    newFunc e p = iOIFromList e p name
    newIOIList = makeIOIList startingBeat deltas
    in do addIOIList env (name,newIOIList)
          addIOI env (name,newFunc)

addIOIs e iois = let 
    addIOI e (x,y,z) = newIOIFunctionAndIOIList e x y z
    in mapM_ (addIOI e) iois