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{-# LANGUAGE ViewPatterns #-}
--------------------------------------------------------------------------------
module Xanthous.Data.EntityMap.Graphics
( visiblePositions
, visibleEntities
, linesOfSight
) where
--------------------------------------------------------------------------------
import Xanthous.Prelude hiding (lines)
--------------------------------------------------------------------------------
import Xanthous.Util (takeWhileInclusive)
import Xanthous.Data
import Xanthous.Data.EntityMap
import Xanthous.Entities
import Xanthous.Util.Graphics (circle, line)
--------------------------------------------------------------------------------
visiblePositions :: Entity e => Position -> Word -> EntityMap e -> Set Position
visiblePositions pos radius = setFromList . positions . visibleEntities pos radius
-- | Returns a list of individual lines of sight, each of which is a list of
-- entities at positions on that line of sight
linesOfSight
:: forall e. Entity e
=> Position
-> Word
-> EntityMap e
-> [[(Position, Vector (EntityID, e))]]
linesOfSight (view _Position -> pos) visionRadius em
= entitiesOnLines
<&> takeWhileInclusive (none (blocksVision . snd) . snd)
where
radius = circle pos $ fromIntegral visionRadius
lines = line pos <$> radius
entitiesOnLines :: [[(Position, Vector (EntityID, e))]]
entitiesOnLines = lines <&> map getPositionedAt
getPositionedAt :: (Int, Int) -> (Position, Vector (EntityID, e))
getPositionedAt p =
let ppos = _Position # p
in (ppos, over _2 (view positioned) <$> atPositionWithIDs ppos em)
-- | Given a point and a radius of vision, returns a list of all entities that
-- are *visible* (eg, not blocked by an entity that obscures vision) from that
-- point
visibleEntities :: Entity e => Position -> Word -> EntityMap e -> EntityMap e
visibleEntities pos visionRadius
= fromEIDsAndPositioned
. fold
. map (\(p, es) -> over _2 (Positioned p) <$> es)
. fold
. linesOfSight pos visionRadius
|
