hastron/src/Hastron/Game/Engine.hs

149 lines
6.6 KiB
Haskell

{-# LANGUAGE GeneralizedNewtypeDeriving #-}
{-# LANGUAGE RecordWildCards #-}
module Hastron.Game.Engine where
import Control.Applicative (Applicative)
import Control.Monad.Identity (Identity, runIdentity)
import Control.Monad.Reader (MonadReader, ask)
import Control.Monad.RWS (MonadRWS, RWST, execRWST)
import Control.Monad.State (MonadState, get, put, modify)
import Control.Monad.Writer (MonadWriter, tell)
import Data.Bifunctor (second)
import Data.DList (DList)
import qualified Data.DList as DList
import qualified Data.HashMap.Strict as Map
import qualified Data.HashSet as Set
import Data.List (foldl')
import Hastron.Game.Types
import Prelude hiding (Left, Right)
newtype GameEngine a =
GameEngine { _runGameEngine :: RWST GameSettings (DList OutEvent) (GameMap, Player) Identity a }
deriving ( Functor
, Applicative
, Monad
, MonadReader GameSettings
, MonadWriter (DList OutEvent)
, MonadState (GameMap, Player)
, MonadRWS GameSettings (DList OutEvent) (GameMap, Player))
stepGameEngine :: GameSettings -> GameMap -> Player -> GameEngine () -> (GameMap, Player, [OutEvent])
stepGameEngine gameSettings gameMap player =
(\((gameMap', player'), outEvents) -> (gameMap', player', DList.toList outEvents))
. runIdentity
. (\rwst -> execRWST rwst gameSettings (gameMap, player))
. _runGameEngine
move :: TimeInterval -> GameEngine ()
move timeElapsed = do
state <- get
settings <- ask
go settings state
where
go GameSettings{ .. } (gameMap@GameMap{ .. }, player@Player{ .. })
| playerState /= PlayerAlive || timeElapsed < 0 = return ()
| not boostActive || boostFuel >= timeElapsed = move'
| otherwise =
move boostFuel >> move (timeElapsed - boostFuel)
where
(x, y) = playerPosition
(Velocity speed dir) = playerVelocity
PlayerBoost{ .. } = playerBoost
dist =
timeElapsed * speed * (if boostActive && boostFuel > 0 then gameBoostFactor else 1)
makeTrail Left = tail [(x', y) | x' <- [x, x - 1 .. x - dist]]
makeTrail Right = tail [(x', y) | x' <- [x .. x + dist]]
makeTrail Up = tail [(x, y') | y' <- [y, y - 1 .. y - dist]]
makeTrail Down = tail [(x, y') | y' <- [y .. y + dist]]
checkTrail trail =
let trail' = takeWhile (not . flip Set.member gameMapBlockedPoints) trail
in if trail' == trail
then (trail, PlayerAlive)
else (trail', PlayerDead)
move' = do
let
revTrail = makeTrail dir
(checkedTrail, playerState') = checkTrail revTrail
trail = reverse checkedTrail
pos' = if null trail then playerPosition else head trail
boostFuel' = if boostActive then boostFuel - timeElapsed else boostFuel
player' = player { playerState = playerState'
, playerPosition = pos'
, playerTrail = trail ++ playerTrail
, playerBoost = playerBoost { boostFuel = boostFuel' }
}
gameMap' = gameMap { gameMapBlockedPoints =
foldl' (flip Set.insert) gameMapBlockedPoints trail }
outEvents = [OutPlayerStateChange playerId playerState' | playerState /= playerState']
put (gameMap', player')
tell $ DList.fromList outEvents
leftTurn :: Direction -> Direction
leftTurn Left = Down
leftTurn Right = Up
leftTurn Up = Left
leftTurn Down = Right
rightTurn :: Direction -> Direction
rightTurn Left = Up
rightTurn Right = Down
rightTurn Up = Right
rightTurn Down = Left
turn :: (Direction -> Direction) -> GameEngine ()
turn turnFn = modify . second $ \player@Player{ playerVelocity = Velocity speed dir } ->
player { playerVelocity = Velocity speed $ turnFn dir }
changeBoost :: Bool -> GameEngine ()
changeBoost boostActive = modify . second $ \player@Player{ .. } ->
player { playerBoost = playerBoost { boostActive = boostActive } }
refillBoost :: Timestamp -> GameEngine ()
refillBoost timeElapsed = do
(gameMap, player@Player{ .. }) <- get
GameSettings{ .. } <- ask
let boostFuel' = floor (fromIntegral timeElapsed * gameBoostRefillFactor)
playerBoost' = playerBoost { boostFuel = boostFuel playerBoost + boostFuel' }
put (gameMap, player { playerBoost = playerBoost' })
tell $ DList.fromList [OutPlayerBoostChange playerId playerBoost' | playerBoost /= playerBoost']
stepGame :: Game -> Timestamp -> InEvent -> (Game, [OutEvent])
stepGame game@Game{ gameMap = gameMap@GameMap{ .. }, .. } time = stepGame'
where
stepGame' (InPlayerTurnLeft playerId) = stepEvent playerId $ turn leftTurn
stepGame' (InPlayerTurnRight playerId) = stepEvent playerId $ turn rightTurn
stepGame' (InPlayerIdle playerId) = stepEvent playerId $ return ()
stepGame' (InPlayerBoostChange playerId boostActive) = stepEvent playerId $ changeBoost boostActive
stepEvent pId step =
flip (maybe (game, [])) (Map.lookup pId gamePlayers) $ \player@Player{ .. } ->
if playerState /= PlayerAlive
then (game, [])
else let
timeElapsed = time - playerLastEventTime
fullStep = move timeElapsed >> step >> refillBoost timeElapsed
(gameMap', player'@Player{ playerPosition = pos'
, playerVelocity = Velocity _ dir' }, outEvents) =
stepGameEngine gameSettings gameMap player fullStep
player'' = player' { playerScore = playerScore + score playerPosition pos'
, playerLastEventTime = time }
game' = game { gamePlayers = Map.insert playerId player'' gamePlayers
, gameMap = gameMap' }
outEvents' = outEvents ++ [OutPlayerPosition playerId pos' dir']
in (game', outEvents')
score (x1, y1) (x2, y2) = abs (x1 - x2) + abs (y1 - y2)
runGame :: Game -> [(Timestamp, InEvent)] -> (Game, [OutEvent])
runGame initialGame =
foldl (\(game, outEvents) (time, inEvent) ->
fmap (outEvents ++) $ stepGame game time inEvent)
(initialGame, [])