Refactor wall drawing

src/Geometry.hs

@@ -347,3 +347,13 @@ lineInPolygon a b ps = pointInPolygon a ps || pointInPolygon b ps
                         || any (isJust . uncurry (intersectSegSeg' a b)) pss
  where pss = zip ps (tail ps ++ [head ps])
 
+makeLoopPairs :: [Point2] -> [(Point2,Point2)]
+makeLoopPairs [] = error "tried to make loop with empty list of points"
+makeLoopPairs (x:[]) = error "tried to make loop with singleton list of points"
+makeLoopPairs (x:xs) = zip (x:xs) (xs ++ [x])
+
+-- note the pair is ordered
+-- doesn't work for obtuse angles
+pointIsInCone :: Point2 -> (Point2,Point2) -> Point2 -> Bool
+pointIsInCone c (rightp,leftp) p = isLHS c rightp p && isLHS leftp c p
+