{-# LANGUAGE AllowAmbiguousTypes #-} module Classes.Physics.Collidible where import Linear -- internal imports import Classes.Physics.Mass data CollisionResult time direction = NoCollision | Collision time direction deriving (Show, Eq) -- | Typeclass for implementing collision results on objects. class (Show c, Mass c) => Collidible c where -- | returns the bottom left and top right corners relative to the objects -- positional vector of the axis aligned bounding box (AABB) serving here -- as collision boundaries. boundary :: c -- ^ Object -> ( V2 Double -- ^ Bottom left corner of AABB relative to position , V2 Double -- ^ Top right corner of AABB relative to position ) collisionCheck :: (Collidible other) => Double -- ^ Time step length -> c -- ^ First object -> other -- ^ second object -> CollisionResult Double (V2 Int) -- ^ Do the objects collide? collisionCheck dt m1 m2 = let d1@(V2 d1x d1y) = (dt *) <$> velocity m1 d2@(V2 d2x d2y) = (dt *) <$> velocity m2 p1 = position m1 p2 = position m2 (m1b1@(V2 m1b1x m1b1y), m1b2@(V2 m1b2x m1b2y)) = boundary m1 (m2b1@(V2 m2b1x m2b1y), m2b2@(V2 m2b2x m2b2y)) = boundary m2 m1p1 = m1b1 m1p2 = V2 m1b1x m1b2y m1p3 = m1b2 m1p4 = V2 m1b2x m1b1y m2p1 = m2b1 m2p2 = V2 m2b1x m2b2y m2p3 = m2b2 m2p4 = V2 m2b2x m2b1y quad1 = map (p1 +) [m1p1, m1p2, m1p3, m1p4] g1 = (m2p1, m2p2) g2 = (m2p2, m2p3) g3 = (m2p3, m2p4) g4 = (m2p4, m2p1) gs = map (\(s1, s2) -> (p2 + s1, p2 + s2)) [g1, g2, g3, g4] t (V2 mqpx mqpy) (ps@(V2 mspx mspy), pt@(V2 mtpx mtpy)) = if d1x == 0 && d1y == 0 then dt else ((mtpx - mqpx) * (-(mtpy - mspy)) - (-(mtpx - mspx)) * (mspy - mqpy)) / (d1x * (-(mtpy - mspy)) - (-(mtpx - mspx)) * d1y) s (V2 mqpx mqpy) (ps@(V2 mspx mspy), pt@(V2 mtpx mtpy)) = (d1x * (mtpy - mqpy) - (mtpx - mqpx) * d1y) / (d1x * (-(mtpy - mspy)) - (-(mtpx - mspx)) * d1y) inside m = let dm = m - (p2 + m2p4) dc = (p2 + m2p3) - (p2 + m2p4) da = (p2 + m2p1) - (p2 + m2p4) in (0 < dm `dot` dc && dm `dot` dc < dc `dot` dc) && (0 < dm `dot` da && dm `dot` da < da `dot` da) in if any inside quad1 then Collision 0 (V2 0 0) else let res = foldl (\acc1 gx -> let gt = foldl (\acc2 q -> let qt = t q gx qs = s q gx in if (qs > 0 && qs < 1) && (qt > 0 && qt < acc2) then qt else acc2 ) (fst acc1) quad1 in if gt < fst acc1 then ( gt , if gx == g1 || gx == g3 then V2 (round $ signum d1x) 0 else V2 0 (round $ signum d1y) ) else acc1 ) (dt, V2 0 0) gs in if fst res < dt then Collision `uncurry` res else NoCollision -- | This Function is called for every collision on both colliding objects. collide :: (Collidible other) => c -- ^ Original object -> other -- ^ Collision partner -> CollisionResult Double (V2 Int) -- ^ Collision reaction -> c -- ^ Updated original object collide = elasticCollision 1 -- | Implementation of a dampened elastic collision used as default collision -- implementation of the collision reaction elasticCollision :: (Collidible c1, Collidible c2) => Double -> c1 -> c2 -> CollisionResult Double (V2 Int) -> c1 elasticCollision _ mo1 _ NoCollision = mo1 elasticCollision damping mo1 mo2 (Collision ddt direction) = let v1@(V2 v1x v1y) = velocity mo1 (V2 v2x v2y) = velocity mo2 p1@(V2 p1x p1y) = position mo1 p2 = position mo2 (V2 m1x1 m1y1, V2 m1x2 m1y2) = boundary mo1 (V2 m2x1 m2y1, V2 m2x2 m2y2) = boundary mo2 m1 = mass mo1 m2 = mass mo2 v1x' = 2 * (m1 * v1x + m2 * v2x) / (m1 + m2) - v1x v1y' = 2 * (m1 * v1y + m2 * v2y) / (m1 + m2) - v1y (V2 dx dy) = p2 - p1 nvel@(V2 nvx nvy) = if m1 == recip 0 then V2 0 0 else (damping *) <$> if m2 == recip 0 then if abs dy < abs dx then (V2 (-v1x) v1y) else (V2 v1x (-v1y)) else (V2 v1x' v1y') bx = if dx < 0 then if abs dx > abs m1x1 + abs m2x2 && (if dy > 0 then abs dy > abs m1y2 + abs m2y1 else abs dy > abs m1y1 + abs m2y2 ) then 0 else (abs m1x1 + abs m2x2) - abs dx else if abs dx > abs m1x2 + abs m2x1 && (if dy > 0 then abs dy > abs m1y2 + abs m2y1 else abs dy > abs m1y1 + abs m2y2 ) then 0 else -((abs m1x2 + abs m2x1) - abs dx) by = if dy < 0 then if abs dy > abs m1y1 + abs m2y2 && (if dx > 0 then abs dx > abs m1x2 + abs m2x1 else abs dx > abs m1x1 + abs m2x2 ) then 0 else (abs m1y1 + abs m2y2) - abs dy else if abs dy > abs m1y2 + abs m2y1 && (if dx > 0 then abs dx > abs m1x2 + abs m2x1 else abs dx > abs m1x1 + abs m2x2 ) then 0 else -((abs m1y2 + abs m2y1) - abs dy) in (velocityUpdater ((positionUpdater mo1) (p1 + if ddt == 0 then if abs by > abs bx then V2 bx 0 else V2 0 by else V2 0 0 ) ) ) nvel