Fix some numerical problems that prevented some very short arcs that were colocated with the edges of a polygon from being recognized as inside the polygon.

git-svn-id: http://svn.stsci.edu/svn/ssb/stsci_python/stsci.sphere/trunk@32335 fe389314-cf27-0410-b35b-8c050e845b92

Former-commit-id: df6e3d7c90b358c56d4f84df17b19a742e405337

1 files changed, 10 insertions, 6 deletions

diff --git a/stsci/sphere/polygon.py b/stsci/sphere/polygon.py
index 06f6b80..2d67ff2 100644
--- a/stsci/sphere/polygon.py
+++ b/stsci/sphere/polygon.py
@@ -498,16 +498,20 @@ class SphericalPolygon(object):
         Determines if this `SphericalPolygon` intersects or contains
         the given arc.
         """
-        return self.contains_point(great_circle_arc.midpoint(a, b))
+        P = self._points
 
-        if self.contains_point(a) and self.contains_point(b):
+        if self.contains_arc(a, b):
             return True
 
-        P = self._points
         intersects = great_circle_arc.intersects(P[:-1], P[1:], a, b)
-        if np.any(intersects):
-            return True
-        return False
+        return np.any(intersects)
+
+    def contains_arc(self, a, b):
+        """
+        Returns `True` if the polygon fully encloses the arc given by a
+        and b.
+        """
+        return self.contains_point(a) and self.contains_point(b)
 
     def area(self):
         r"""