src/RMCA/Layer/Layer.hs

   1 {-# LANGUAGE Arrows #-}
   2
   3 module RMCA.Layer.Layer where
   4
   5 import Data.CBMVar
   6 import Data.ReactiveValue
   7 import FRP.Yampa
   8 import RMCA.Global.Clock
   9 import RMCA.Semantics
  10
  11 -- Data representing the state of a layer. It is updated continuously.
  12 data Layer = Layer { relTempo    :: Double
  13                    , relPitch    :: RelPitch
  14                    , strength    :: Strength
  15                    , beatsPerBar :: BeatsPerBar
  16                    } deriving (Show)
  17
  18 layerTempo :: SF (Tempo, Layer) LTempo
  19 layerTempo = proc (t, Layer { relTempo = r }) ->
  20   returnA -< floor $ r * fromIntegral t
  21
  22 -- The layer is modified after the beat as been
  23 layerMetronome' :: BeatNo -> SF (Tempo, Layer) (Event BeatNo)
  24 layerMetronome' b = proc (t, l@Layer { beatsPerBar = bpb }) -> do
  25   eb <- metronome <<< layerTempo -< (t, l)
  26   returnA -< eb `tag` nextBeatNo bpb b
  27
  28 layerMetronome :: SF (Tempo, Layer) (Event BeatNo)
  29 layerMetronome = layerMetronome'' 0
  30   where layerMetronome'' no = dSwitch (layerMetronome' no >>^ dup)
  31                               layerMetronome''
  32
  33 layerRV :: CBMVar Layer -> ReactiveFieldReadWrite IO Layer
  34 layerRV mvar = ReactiveFieldReadWrite setter getter notifier
  35   where setter :: Layer ->  IO ()
  36         setter = writeCBMVar mvar
  37
  38         getter :: IO Layer
  39         getter = readCBMVar mvar
  40
  41         notifier :: IO () -> IO ()
  42         notifier = installCallbackCBMVar mvar
  43
  44 getDefaultLayerRV :: IO (ReactiveFieldReadWrite IO Layer)
  45 getDefaultLayerRV = layerRV <$> newCBMVar dl
  46   where dl = Layer { relTempo = 1
  47                    , relPitch = 0
  48                    , strength = 1
  49                    , beatsPerBar = 4
  50                    }