Correctly intersect lines and circles

src/Geometry/Intersect.hs

@@ -251,10 +251,16 @@ orthogonalPointOnSeg a b p
     | otherwise              = Just $ a +.+ param *.* (normalizeV $ b -.- a)
   where
     param = closestPointOnLineParam a b p
+
+inSegArea :: Point2 -> Point2 -> Point2 -> Bool
+inSegArea a b c = param >= 0 && param <= dotV (b -.- a) (b -.- a)
+  where
+    param = dotV (b -.- a) (c -.- a)
+
 intersectCircSeg :: Point2 -> Float -> Point2 -> Point2 -> [Point2]
 intersectCircSeg c r a b 
     | y < 0 = []
-    | otherwise = nub $ filter ( (< dist a b) . dist a ) [ d -.- v, d +.+ c ]
+    | otherwise = nub $ filter (inSegArea a b) [ d -.- v, d +.+ c ]
   where
     d = closestPointOnLine a b c
     x = dist d c