Preserve nonempty points and segments when simplifying region unions

blueprint/src/python/helpers/region_helper.py

@@ -16,7 +16,7 @@ def simplify_union_of_polys(polys, union_fn, track_dependencies=False):
 
         # Remove all empty polytopes
         for i in range(len(polys)):
-            if polys[i].is_empty(include_boundary=False):
+            if polys[i].is_empty(include_boundary=True):
                 index.remove(i)
 
         # Keep track of the tuples (int, int) of indexes which do not form a pairwise

blueprint/src/python/tests/test_thin_union_regression.py

@@ -0,0 +1,21 @@
+from polytope import Polytope
+from region import Region
+
+
+def test_simplification_preserves_isolated_point():
+    point = Polytope.rect((2, 2), (3, 3))
+    region = Region.union([Region.from_polytope(point)])
+    assert region.contains((2, 3))
+    region.simplify()
+    assert region.contains((2, 3))
+    assert not region.contains((2, 4))
+
+
+def test_simplification_preserves_segment_outside_full_dimensional_component():
+    rectangle = Polytope.rect((0, 1), (0, 1))
+    segment = Polytope.rect((2, 2), (0, 1))
+    region = Region.union([Region.from_polytope(rectangle), Region.from_polytope(segment)])
+    points = [(0, 0), (0.5, 0.5), (2, 0), (2, 0.5), (2, 1), (1.5, 0.5)]
+    before = [region.contains(point) for point in points]
+    region.simplify()
+    assert [region.contains(point) for point in points] == before