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module Game.Entities.Common
( toSpriteSet,
frameLimit,
collision,
inLine,
facingLower,
updateFrame,
updateGravity,
turn,
)
where
import Data.IORef
import Game.Entities.Const
import Game.Entities.Types
import Game.Sprites qualified as S
-- | Return the opposite direction.
turn :: Dir -> Dir
turn DirRight = DirLeft
turn DirLeft = DirRight
-- | Convert direction into a sprite set.
toSpriteSet :: Dir -> Int
toSpriteSet DirRight = 0
toSpriteSet DirLeft = 1
-- | Return the number of frames available on the entity's sprite for current direction.
frameLimit :: Entity -> Int
frameLimit e = S.frameCount e.sprite e.set
-- | Collision detection of player vs entity.
--
-- The player's head won't register, this is necessary to avoid hitting things on a platform above when jumping.
collision :: IORef Entity -> Int -> Collision
collision playerRef otherHeight other = do
player <- readIORef playerRef
pure $
player.typ == TypePlayer
&& player.x + 4 < other.x + 12
&& other.x + 4 < player.x + 12
&& player.y + otherHeight - 4 < other.y + otherHeight
&& other.y + 4 < player.y + 24
-- | Check if the player is in line with the entity and the entity is facing the player.
inLine :: IORef Entity -> Int -> Collision
inLine playerRef otherHeight other = do
player <- readIORef playerRef
pure $
player.typ == TypePlayer
&& player.y + otherHeight - 4 < other.y + otherHeight
&& other.y + 4 < player.y + 24
-- XXX: adjust perhaps? so the enemies don't shoot too close to the player
&& ( (other.dir == DirLeft && player.x < other.x)
|| (other.dir == DirRight && player.x > other.x)
)
-- | Check if the entity is facing the player and it is in a lower plarform.
facingLower :: IORef Entity -> Collision
facingLower playerRef other = do
player <- readIORef playerRef
pure $
player.typ == TypePlayer
&& player.gravity == gravityOff
&& player.y < other.y
&& ( (other.dir == DirLeft && player.x < other.x)
|| (other.dir == DirRight && player.x > other.x)
)
-- | Update frame animation for entities that have direction.
updateFrame :: Bool -> Entity -> Entity
updateFrame updated e
| isGravityOn = e
| e.delay > 0 = e {delay = e.delay - 1}
| e.frame + 1 < frameLimit e = e {delay = frameDelay, frame = if updated then e.frame + 1 else 0}
| otherwise = e {delay = frameDelay, frame = 0}
where
isGravityOn = e.gravity > gravityOff
applyGravity :: IsBlocked -> Int -> Entity -> Entity
applyGravity isBlocked v e
| v == 0 = e
-- hit the floor
| isGoingDown
&& (isBlocked (e.x + 4) (e.y + 24) || isBlocked (e.x + 10) (e.y + 24))
&& not (isBlocked (e.x + 4) (e.y + 23))
&& not (isBlocked (e.x + 10) (e.y + 23)) =
e {jumping = False, gravity = gravityOff, delay = 0}
| otherwise = applyGravity isBlocked (v - 1) e {y = e.y + change}
where
isGoingDown = e.gravity >= gravityDown
change = if isGoingDown then 1 else -1
-- XXX: hardcoded to 16x24 pixels sprite.
updateGravity :: IsBlocked -> Entity -> Entity
updateGravity isBlocked e
| current > gravityOff = applyGravity isBlocked (gravityTable !! current) e {gravity = new}
| not (isBlocked (e.x + 4) (e.y + 24) || isBlocked (e.x + 10) (e.y + 24)) = e {gravity = gravityDown, frame = jumpFrame}
| otherwise = e
where
current = e.gravity
new = if current > gravityOff && current < length gravityTable - 1 then current + 1 else current
|
