Work on chasm rooms

src/Geometry/Intersect.hs

@@ -15,9 +15,9 @@ import Linear.Metric
 import Control.Monad
 
 -- | If two lines intersect, return 'Just' that point.
-intersectLineLine' :: Point2 -> Point2 -> Point2 -> Point2 -> Maybe Point2
-{-# INLINE intersectLineLine' #-}
-intersectLineLine' (V2 x1 y1) (V2 x2 y2) (V2 x3 y3) (V2 x4 y4)
+intersectLineLine :: Point2 -> Point2 -> Point2 -> Point2 -> Maybe Point2
+{-# INLINE intersectLineLine #-}
+intersectLineLine (V2 x1 y1) (V2 x2 y2) (V2 x3 y3) (V2 x4 y4)
     | den == 0 = Nothing
     | otherwise = Just $ V2 (x1 + (x2 - x1) * t' / den) (y1 + (y2 - y1) * t' / den)
   where
@@ -28,7 +28,7 @@ intersectLineLine' (V2 x1 y1) (V2 x2 y2) (V2 x3 y3) (V2 x4 y4)
 intersectLinePlane :: Point3 -> Point3 -> Point3 -> Point3 -> Maybe Point3
 intersectLinePlane l v p n = case dot v n of
     0 -> Nothing
-    x -> Just $ l + ((dot (p - l) n) / x) *.*.* v
+    x -> Just $ l + (dot (p - l) n / x) *.*.* v
 
 -- this needs to be checked
 intersectSegPlane :: Point3 -> Point3 -> Point3 -> Point3 -> Maybe Point3

src/Geometry/Polygon.hs

@@ -2,6 +2,7 @@
 
 module Geometry.Polygon where
 
+import Geometry.Intersect
 import qualified Control.Foldl as L
 import Data.Maybe
 import Geometry.Data
@@ -46,6 +47,23 @@ rectVV (V2 x y) (V2 a b) = rectNSWE n s w e
 square :: Float -> [Point2]
 square n = rectWH n n
 
+polyOrthDist :: Int -> Float -> [Point2]
+polyOrthDist n x = mapMaybe
+            (\(ra, rb) -> intersectLineLine (rotateV ra bl) (rotateV ra br) (rotateV rb bl) (rotateV rb br))
+            $ loopPairs rots
+  where
+    rot = 2 * pi / fromIntegral n
+    rots = map ((rot *) . fromIntegral) [0 .. n -1]
+    bl = V2 x x
+    br = V2 (- x) x
+
+polyCornerDist :: Int -> Float -> [Point2]
+polyCornerDist n x = map f rots
+  where
+    rot = 2 * pi / fromIntegral n
+    rots = map ((rot *) . fromIntegral) [0 .. n -1]
+    f a = rotateV a (V2 x 0)
+
 mirrorXAxis :: [Point2] -> [Point2]
 mirrorXAxis ps = orderPolygon $ ps ++ mapMaybe f ps
   where