Luc Maisonobe created MATH-1266:
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Summary: split and side methods may be inconsistent in BSP trees
Key: MATH-1266
URL: https://issues.apache.org/jira/browse/MATH-1266
Project: Commons Math
Issue Type: Bug
Affects Versions: 3.5
Reporter: Luc Maisonobe
Assignee: Luc Maisonobe
In BSP trees, there are two related methods dealing with the relative position
of a sub-hyperplane and an hyperplane: side and split.
sub.side(hyperplane) returns an enumerate (PLUS, MINUS, BOTH, HYPER) telling
the relative position of the syb-hyperplane with respect to the hyperplane.
sub.split(hyperplane) splits the sub-hyperplane in two parts, one on the plus
side of the hyperplane and one on the minus side of the hyperplane.
These methods should be consistent, i.e. when side returns BOTH, then split
should return two non-null parts. This fails in the following case:
{code}
@Test
public void testSideSplitConsistency() {
double tolerance = 1.0e-6;
Circle hyperplane = new Circle(new Vector3D(9.738804529764676E-5,
-0.6772824575010357, -0.7357230887208355),
tolerance);
SubCircle sub = new SubCircle(new Circle(new
Vector3D(2.1793884139073498E-4, 0.9790647032675541, -0.20354915700704285),
tolerance),
new ArcsSet(4.7121441684170700,
4.7125386635004760, tolerance));
SplitSubHyperplane<Sphere2D> split = sub.split(hyperplane);
Assert.assertNotNull(split.getMinus());
Assert.assertNull(split.getPlus());
Assert.assertEquals(Side.MINUS, sub.side(hyperplane));
}
{code}
In fact, it is only one particular case, the same could occur in other spaces
(Euclidean or Spherical, and on various dimensions)
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