affection/src/Affection/Animation.hs

{-# LANGUAGE RecordWildCards #-}

module Affection.Animation
  ( SpriteAnimation(..)
  , runAnimation
  ) where

import Affection.Actor
import Affection.Types
import Affection.Property

import qualified GEGL as G

import Control.Monad.State

data SpriteAnimation = SpriteAnimation
  { sanimCurrentFrame :: Int
  , sanimSprites :: [FilePath]
  , sanimFrameDuration :: Double
  , sanimLoop :: Bool
  , sanimLastChange :: Double
  , sanimPropName :: String
  }

runAnimation
  :: (Show a, Ord a)
  => Actor a
  -> SpriteAnimation
  -> Affection us (SpriteAnimation, Actor a)
runAnimation act anim@SpriteAnimation{..} = do
  ad <- get
  let elapsed = elapsedTime ad
  if elapsed - sanimLastChange > sanimFrameDuration
  then do
    let nframe =
          if sanimCurrentFrame + 1 > length sanimSprites
          then
            if sanimLoop then 1 else sanimCurrentFrame
          else sanimCurrentFrame + 1
        nact =
          updateProperties
          (props $ prop sanimPropName $ sanimSprites !! (nframe - 1))
          act
    return (anim
      { sanimCurrentFrame = nframe
      , sanimLastChange = elapsed
      }, nact)
  else
    return (anim, act)