When multiple points for openmc.model.Polygon are colinear the polygon decomposes in part into a line and breaks the underlying geometry engine. The question though is why would you ever specify colinear points? I was working on hackily creating polygons from an SVG file. In this case SVG interpreters don't care about colinearity, and this can happen.
QhullError Traceback (most recent call last)
Cell In[1], line 2
1 import openmc
----> 2 openmc.model.Polygon([
3 (43.08936, -13.206429),
4 (43.08936, -22.855452),
5 (44.236576, -22.855452),
6 (44.236576, -18.930111),
7 (44.236576, -16.989144),
8 (44.236576, -13.206429),
9 (43.08936, -13.206429),
10 ])
File ~/mambaforge/lib/python3.10/site-packages/openmc/model/surface_composite.py:818, in Polygon.__init__(self, points, basis)
814 self._constrain_triangulation(self._validate_points(points))
816 # Decompose the polygon into groups of simplices forming convex subsets
817 # and get the sets of (surface, operator) pairs defining the polygon
--> 818 self._surfsets = self._decompose_polygon_into_convex_sets()
820 # Set surface names as required by CompositeSurface protocol
821 surfnames = []
File ~/mambaforge/lib/python3.10/site-packages/openmc/model/surface_composite.py:1190, in Polygon._decompose_polygon_into_convex_sets(self)
1188 groups = []
1189 while neighbor_map:
-> 1190 groups.append(self._group_simplices(neighbor_map))
1191 self._groups = groups
1193 # Generate lists of (surface, operator) pairs for each convex
1194 # sub-region.
File ~/mambaforge/lib/python3.10/site-packages/openmc/model/surface_composite.py:1075, in Polygon._group_simplices(self, neighbor_map, group)
1073 if group is None:
1074 sidx = next(iter(neighbor_map))
-> 1075 return self._group_simplices(neighbor_map, group=[sidx])
1076 # Otherwise use the last simplex in the group
1077 else:
1078 sidx = group[-1]
File ~/mambaforge/lib/python3.10/site-packages/openmc/model/surface_composite.py:1090, in Polygon._group_simplices(self, neighbor_map, group)
1088 test_points = self.points[test_point_idx]
1089 # If test_points are convex keep adding to this group
-> 1090 if len(test_points) == len(ConvexHull(test_points).vertices):
1091 group = self._group_simplices(neighbor_map, group=test_group)
1092 return group
File _qhull.pyx:2431, in scipy.spatial._qhull.ConvexHull.__init__()
File _qhull.pyx:353, in scipy.spatial._qhull._Qhull.__init__()
QhullError: QH6013 qhull input error: input is less than 2-dimensional since all points have the same x coordinate 44.24
While executing: | qhull i Qt
Options selected for Qhull 2019.1.r 2019/06/21:
run-id 179452238 incidence Qtriangulate _pre-merge _zero-centrum
_max-width 9.6 Error-roundoff 3.8e-14 _one-merge 1.9e-13
_near-inside 9.5e-13 Visible-distance 7.6e-14 U-max-coplanar 7.6e-14
Width-outside 1.5e-13 _wide-facet 4.5e-13 _maxoutside 2.3e-13
Bug Description
When multiple points for
openmc.model.Polygonare colinear the polygon decomposes in part into a line and breaks the underlying geometry engine. The question though is why would you ever specify colinear points? I was working on hackily creating polygons from an SVG file. In this case SVG interpreters don't care about colinearity, and this can happen.I was attempting to create this:
The problematic polygon looks like:
Steps to Reproduce
MWE:
This leads to:
Environment
Openmc 0.14. See #2930 for details.