simplify polygon/ellipse intersection

smichr · Mar 17, 2024 · 993e3be · 993e3be
1 parent b0f460f
commit 993e3be
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Showing 2 changed files with 11 additions and 14 deletions.
diff --git a/sympy/geometry/ellipse.py b/sympy/geometry/ellipse.py
@@ -755,20 +755,16 @@ def is_tangent(self, o):
             else:
                 return False
         elif isinstance(o, Polygon):
-            all_tangents = False
-            segments = o.sides if isinstance(o, Polygon) else [o]
-            for segment in segments:
-                intersect = self.intersection(segment)
-                if len(intersect) == 1:
-                    if not any(intersect[0] in i for i in segment.points) \
-                        and not any(self.encloses_point(i) for i in segment.points):
-                        all_tangents = True
-                        continue
-                    else:
-                        return False
+            # True if any tangent and no crossing
+            saw_tangent = False
+            for segment in o.sides:
+                if self.is_tangent(segment):
+                    saw_tangent = True
                 else:
-                    return False
-            return all_tangents
+                    intersect = self.intersection(segment)
+                    if intersect:
+                        return False
+            return saw_tangent
         elif isinstance(o, (LinearEntity3D, Point3D)):
             raise TypeError('Entity must be two dimensional, not three dimensional')
         else:

diff --git a/sympy/geometry/tests/test_ellipse.py b/sympy/geometry/tests/test_ellipse.py
@@ -453,6 +453,7 @@ def test_is_tangent():
     assert c1.is_tangent(Ray((-3, -22), (15, 20))) is False
     assert c1.is_tangent(Ray((9, 20), (9, -20))) is True
     assert c1.is_tangent(Ray((2, 5), (9, 5))) is True
+    assert c1.is_tangent(Segment((2, 5), (9, 5))) is True
     assert e1.is_tangent(Segment((2, 2), (-7, 7))) is False
     assert e1.is_tangent(Segment((0, 0), (1, 2))) is False
     assert c1.is_tangent(Segment((0, 0), (-5, -2))) is False
@@ -472,7 +473,7 @@ def test_is_tangent():
     assert e1.is_tangent(Polygon((-3, -5), (-3, 5), (3, 5), (3, -5))) is True
     assert c1.is_tangent(Polygon((-3, -5), (-3, 5), (3, 5), (3, -5))) is False
     assert e1.is_tangent(Polygon((0, 0), (3, 0), (7, 7), (0, 5))) is False
-    assert e1.is_tangent(Polygon((3, 12), (3, -12), (6, 5))) is False
+    assert e1.is_tangent(Polygon((3, 12), (3, -12), (6, 5))) is True # at (3,0)
     assert e1.is_tangent(Polygon((3, 12), (3, -12), (0, -5), (0, 5))) is False
     assert e1.is_tangent(Polygon((3, 0), (5, 7), (6, -5))) is False
     assert c1.is_tangent(Segment((0, 0), (-5, -2))) is False