From cd60109a77dd7a3e6a492ef734684af272fb5cce Mon Sep 17 00:00:00 2001
From: shimwell <mail@jshimwell.com>
Date: Wed, 13 Jul 2022 19:14:14 +0100
Subject: [PATCH] added bounding_region

---
 openmc/universe.py                            | 43 +++++++++++++++++++
 .../regression_tests/dagmc/universes/test.py  | 14 ++++++
 2 files changed, 57 insertions(+)

diff --git a/openmc/universe.py b/openmc/universe.py
index b65263ef9..2fd931506 100644
--- a/openmc/universe.py
+++ b/openmc/universe.py
@@ -713,6 +713,49 @@ class DAGMCUniverse(UniverseBase):
         dagmc_element.set('filename', self.filename)
         xml_element.append(dagmc_element)
 
+    def bounding_region(self, bounded_type='box', boundary_type='vacuum'):
+        """Creates a either a spherical or box shaped bounding region around
+        the DAGMC geometry.
+        Parameters
+        ----------
+        bounded_type : str
+            The type of bounding surface(s) to use when constructing the region.
+            Options include a single spherical surface (sphere) or a rectangle
+            made from siz planes (box).
+        boundary_type : str
+            Boundary condition that defines the behavior for particles hitting
+            the surface. Defaults to vacuum boundary condition. Passed into
+        Returns
+        -------
+        openmc.Region
+            Region instance
+        """
+
+        bounding_box = self.bounding_box
+
+        if bounded_type == 'sphere':
+            import math
+            bounding_box_center = (bounding_box[0] + bounding_box[1])/2
+            radius = math.dist(bounding_box[0], bounding_box[1])
+            bounding_surface = openmc.Sphere(x0=bounding_box_center[0], y0=bounding_box_center[1], z0=bounding_box_center[2], r=radius)
+
+            return -bounding_surface
+
+        if bounded_type == 'box':
+            # defines plane surfaces for all six faces of the bounding box
+            lower_x = openmc.XPlane(bounding_box[0][0], boundary_type=boundary_type)
+            upper_x = openmc.XPlane(bounding_box[1][0], boundary_type=boundary_type)
+            lower_y = openmc.YPlane(bounding_box[0][1], boundary_type=boundary_type)
+            upper_y = openmc.YPlane(bounding_box[1][1], boundary_type=boundary_type)
+            lower_z = openmc.ZPlane(bounding_box[0][2], boundary_type=boundary_type)
+            upper_z = openmc.ZPlane(bounding_box[1][2], boundary_type=boundary_type)
+
+            return +lower_x & -upper_x & +lower_y & -upper_y & +lower_z & -upper_z
+
+    def bounded_universe(self, **kwargs):
+        bounding_cell = openmc.Cell(fill=self, region=self.bounding_region(**kwargs))
+        return openmc.Universe(cells=[bounding_cell])
+
     @classmethod
     def from_hdf5(cls, group):
         """Create DAGMC universe from HDF5 group
diff --git a/tests/regression_tests/dagmc/universes/test.py b/tests/regression_tests/dagmc/universes/test.py
index 6726b4b44..f6964857d 100644
--- a/tests/regression_tests/dagmc/universes/test.py
+++ b/tests/regression_tests/dagmc/universes/test.py
@@ -51,6 +51,20 @@ class DAGMCUniverseTest(PyAPITestHarness):
         assert bounding_box[0].tolist() == [-25., -25., -25.]
         assert bounding_box[1].tolist() == [25., 25., 25.]
 
+        # checks that the bounding region is six surfaces each with a vacuum boundary type
+        b_region = pincell_univ.bounding_region(bounded_type='box', boundary_type='vacuum')
+        assert isinstance(b_region, openmc.Region)
+        assert len(b_region.get_surfaces()) == 6
+        for surface in list(b_region.get_surfaces().values()):
+            assert surface.boundary_type == 'vacuum'
+
+        # checks that the bounding region is a single surface with a reflective boundary type
+        b_region = pincell_univ.bounding_region(bounded_type='sphere', boundary_type='reflective')
+        assert isinstance(b_region, openmc.Region)
+        assert len(b_region.get_surfaces()) == 1
+        for surface in list(b_region.get_surfaces().values()):
+            assert surface.boundary_type == 'reflective'
+
         # create a 2 x 2 lattice using the DAGMC pincell
         pitch = np.asarray((24.0, 24.0))
         lattice = openmc.RectLattice()