brillo-examples-1.13.3: picture/Boids/Vec2.hs

{-# LANGUAGE BangPatterns #-}

module Vec2 where


data Vec2
  = Vec2 {-# UNPACK #-} !Double {-# UNPACK #-} !Double
  deriving (Show)


vecZero :: Vec2
vecZero = Vec2 0.0 0.0


vecAdd :: Vec2 -> Vec2 -> Vec2
vecAdd (Vec2 a b) (Vec2 x y) =
  Vec2 (a + x) (b + y)


vecSub :: Vec2 -> Vec2 -> Vec2
vecSub (Vec2 a b) (Vec2 x y) =
  Vec2 (a - x) (b - y)


vecScale :: Vec2 -> Double -> Vec2
vecScale (Vec2 a b) !s =
  Vec2 (a * s) (b * s)


vecDot :: Vec2 -> Vec2 -> Double
vecDot (Vec2 a b) (Vec2 x y) =
  (a * x) + (b * y)


vecNorm :: Vec2 -> Double
vecNorm v =
  sqrt (vecDot v v)


vecNormalize :: Vec2 -> Vec2
vecNormalize v =
  vecScale v (1.0 / (vecNorm v))


vecDimSelect :: Vec2 -> Int -> Double
vecDimSelect (Vec2 a b) n =
  case rem n 2 of
    0 -> a
    _ -> b


vecLessThan :: Vec2 -> Vec2 -> Bool
vecLessThan (Vec2 a b) (Vec2 x y) =
  a < x && b < y


vecGreaterThan :: Vec2 -> Vec2 -> Bool
vecGreaterThan (Vec2 a b) (Vec2 x y) =
  a > x && b > y