RCMA/Layer/Layer.hs

   1 {-# LANGUAGE Arrows #-}
   2
   3 module RCMA.Layer.Layer where
   4
   5 import Data.CBMVar
   6 import Data.ReactiveValue
   7 import FRP.Yampa
   8 import RCMA.Global.Clock
   9 import RCMA.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                    , beatCounter :: BeatNo
  17                    }
  18
  19 layerTempo :: SF (Tempo, Layer) LTempo
  20 layerTempo = proc (t, Layer { relTempo = r }) -> do
  21   returnA -< floor $ r * fromIntegral t
  22
  23 -- The layer is modified after the beat as been
  24 layerMetronome :: SF (Tempo, Layer) (Event (BeatNo, Layer))
  25 layerMetronome = proc (t, l@Layer { beatCounter = b , beatsPerBar = bpb}) -> do
  26   eb <- metronome <<< layerTempo -< (t, l)
  27   returnA -< eb `tag` let nb = nextBeatNo b bpb in (nb, l { beatCounter = nb })
  28
  29 layerRV :: CBMVar Layer -> ReactiveFieldReadWrite IO Layer
  30 layerRV mvar = ReactiveFieldReadWrite setter getter notifier
  31   where setter :: Layer ->  IO ()
  32         setter = writeCBMVar mvar
  33
  34         getter :: IO Layer
  35         getter = readCBMVar mvar
  36
  37         notifier :: IO () -> IO ()
  38         notifier = installCallbackCBMVar mvar
  39
  40 getDefaultLayerRV :: IO (ReactiveFieldReadWrite IO Layer)
  41 getDefaultLayerRV = layerRV <$> newCBMVar dl
  42   where dl = Layer { relTempo = 1
  43                    , relPitch = 0
  44                    , strength = 127
  45                    , beatsPerBar = 4
  46                    , beatCounter = 0
  47                    }