diff options
Diffstat (limited to 'lib/Grav2ty/Simulation.hs')
| -rw-r--r-- | lib/Grav2ty/Simulation.hs | 27 |
1 files changed, 24 insertions, 3 deletions
diff --git a/lib/Grav2ty/Simulation.hs b/lib/Grav2ty/Simulation.hs index 6214a99..86fcd4f 100644 --- a/lib/Grav2ty/Simulation.hs +++ b/lib/Grav2ty/Simulation.hs @@ -31,6 +31,7 @@ import Linear.Metric (norm, distance) import Linear.V2 import Linear.Vector +-- | @translateHitbox (V2 x y)@ translates a 'Hitbox' by (x, y) in a 2d plane. translateHitbox :: Num a => V2 a -> Hitbox a -> Hitbox a translateHitbox t (HLine a b) = HLine (a + t) (b + t) translateHitbox t (HCircle c r) = HCircle (c + t) r @@ -39,13 +40,17 @@ translateHitbox t (HCombined hs) = HCombined . map (translateHitbox t) $ hs complexV2 :: Iso' (Complex a) (V2 a) complexV2 = iso (\(x :+ y) -> V2 x y) (\(V2 x y) -> x :+ y) --- | Rotate a point by an radial angle around @V2 0 0@ +-- | Rotate a point by an radial angle around @V2 0 0@ using 'Complex' multiplication. +-- When using this rotation make sure to rotate before translating. rotateV2 :: RealFloat a => a -> V2 a -> V2 a rotateV2 angle = (^. complexV2) . (* rotator) . (^. from complexV2) where rotator = cos angle :+ sin angle -- TODO address inaccuracies of 'Float' and 'Double'? --- | Rotate a 'Hitbox' by a radial angle. +-- | @rotateHitbox@ rotates a 'Hitbox' by the given angle +-- which must be radial. As it uses 'Complex' multiplication +-- the center of the rotation is always @V2 0 0@, so make +-- sure to rotate before translating a 'Hitbox'. rotateHitbox :: RealFloat a => a -> Hitbox a -> Hitbox a rotateHitbox angle box = case box of @@ -53,7 +58,7 @@ rotateHitbox angle box = HCircle c r -> HCircle (rotateV2 angle c) r HCombined l -> HCombined . map (rotateHitbox angle) $ l --- | Returns the 'Hitbox' for an 'Object', but rotated and translated +-- | Returns the 'Hitbox' for an 'Object' — rotated and translated -- to the location it is *actually* at. realHitbox :: RealFloat a => Object a -> Hitbox a realHitbox obj = translateHitbox (objectLoc obj) . rotateHitbox (objectRot obj) @@ -70,6 +75,7 @@ cramer2 coeff res = if detA == 0 a1 = set (column _x) res coeff a2 = set (column _y) res coeff +-- | Wether a value is between two other values. inRange :: Ord a => (a, a) -> a -> Bool inRange (l, u) x = x >= l && x <= u @@ -125,14 +131,19 @@ collision (HLine a1 b1) (HLine a2 b2) = collision (HCombined as) b = any (collision b) as collision a b@(HCombined _) = collision b a +-- | Wether two given 'Object's collide. objectCollision :: RealFloat a => Object a -> Object a -> Bool objectCollision a b = a /= b && ((objectLoc a == objectLoc b) || collision (realHitbox a) (realHitbox b)) +-- | Wether two 'Object's have a certain distance. Used to +-- prevent extreme spikes in gravitational force while simulating +-- two objects that are close together. separated :: (Floating a, Ord a) => Object a -> Object a -> Bool separated a b = distance (objectLoc a) (objectLoc b) > 3 +-- | Directional Gravitational Force between two Objects as two-dimensional vector. gravitationForce :: Floating a => Object a -> Object a -> V2 a gravitationForce a b = (gravityConst * ((objectMass a * objectMass b) / (absDistance ** 2))) @@ -141,6 +152,7 @@ gravitationForce a b = (gravityConst * distance = objectLoc b - objectLoc a absDistance = norm distance +-- | The sum of gravitational force the 'World' imposes on an 'Object'. gravitationForces :: (Ord a, Floating a) => World a -> Object a -> V2 a gravitationForces world obj = foldl' calcSum (pure 0) world where calcSum force x = if separated obj x @@ -154,8 +166,13 @@ data ObjRel a = ObjRel makeLenses 'ObjRel +-- | The Object Relation Graph is used to store collisions +-- and the forces between 'Object's. This prevents that +-- these values are computed more than once and allows +-- to reuse computations for the inverse relation. type ObjRelGraph a = RelGraph Id (ObjRel a) +-- | Calculates all 'ObjRel's for a 'World'. objectRelGraph :: (RealFloat a, Ord a) => World a -> ObjRelGraph a objectRelGraph = insertMapKey rel emptyRel where rel a b = let res = ObjRel (objectCollision a b) (gravity a b) @@ -164,6 +181,10 @@ objectRelGraph = insertMapKey rel emptyRel then gravitationForce a b else pure 0 +-- | @updateObject timeStep gravitionForce@ calculates the state of +-- an 'Object' after a certain @timeStep@ of being exposed to +-- a certain @gravitationForce@. It also factors in the current +-- acceleration and speed of the 'Object'. updateObject :: Fractional a => a -> V2 a -> Object a -> Object a updateObject _ _ obj@Static {} = obj updateObject timeStep force obj@Dynamic {} = obj |