{- The MIT License Copyright (c) 2010 Korcan Hussein Permission is hereby granted, free of charge, to any person obtaining a copy of this software and associated documentation files (the "Software"), to deal in the Software without restriction, including without limitation the rights to use, copy, modify, merge, publish, distribute, sublicense, and/or sell copies of the Software, and to permit persons to whom the Software is furnished to do so, subject to the following conditions: The above copyright notice and this permission notice shall be included in all copies or substantial portions of the Software. THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE. -} {-# LANGUAGE MultiParamTypeClasses #-} module Collision where import Vector2 class Collision a b where intersect :: a -> b -> Bool newtype Bounds = Bounds { sides :: (Float,Float,Float,Float) } instance Collision Bounds Bounds where Bounds (ax, ay, aw, ah) `intersect` Bounds (bx, by, bw, bh) | t1 > bw || (-t1) > aw = False | t2 > bh || (-t2) > ah = False | otherwise = True where t1 = ax - bx t2 = ay - by -- Dynamic seperating-axis test intersectMoving :: Bounds -> Bounds -> Vector2f -> Vector2f -> Maybe (Float,Float) intersectMoving a@(Bounds (ax, ay, aw, ah)) b@(Bounds (bx, by, bw, bh)) va vb | intersect a b = Just (0,0) | otherwise = do let v = vb `sub` va -- test x-axis (t1, t2) <- test (fst v) 0 1 ax maxAx bx maxBx -- test y-axis test (snd v) t1 t2 ay maxAy by maxBy where maxAx = ax + aw maxAy = ay + ah maxBx = bx + bw maxBy = by + bh test vi tfirst tlast aMin aMax bMin bMax = case test1 vi tfirst tlast aMin aMax bMin bMax of Just (t1, t2) -> if t1 > t2 then Nothing else Just (t1,t2) _ -> Nothing test1 vi tfirst tlast aMin aMax bMin bMax | vi < 0.0 = if bMax < aMin then Nothing -- no-interesection will occur else let t1 = if aMax < bMin then max ((aMax - bMin) / vi) tfirst else tfirst t2 = if bMax > aMin then min ((aMin - bMax) / vi) tlast else tlast in Just (t1,t2) | vi > 0.0 = if bMin > aMax then Nothing -- no-interesection will occur else let t1 = if bMax < aMin then max ((aMin - bMax) / vi) tfirst else tfirst t2 = if aMax > bMin then min ((aMax - bMin) / vi) tlast else tlast in Just (t1,t2) | otherwise = -- zero component if bMax < aMin || bMin > aMax then Nothing -- no-interesection else Just (max 0.0 tfirst, min 1.0 tlast)