Merge pull request #6154 from afabri/Nef_3-fix_comparison-GF

Nef_3: Fix broken greater-than

Nef_3/include/CGAL/Nef_polyhedron_3.h

@@ -1549,7 +1549,7 @@ protected:
   { return !N1.difference(*this).is_empty() && difference(N1).is_empty(); }
 
   bool operator>(const Nef_polyhedron_3<Kernel,Items, Mark>& N1) const
-  { return difference(*this).is_empty() && !difference(N1).is_empty(); }
+  { return N1.difference(*this).is_empty() && !difference(N1).is_empty(); }
 
   bool operator<=(const Nef_polyhedron_3<Kernel,Items, Mark>& N1) const
   { return difference(N1).is_empty(); }

Nef_3/test/Nef_3/test_nef_3_operator.cpp

@@ -0,0 +1,29 @@
+#include <CGAL/Exact_predicates_exact_constructions_kernel.h>
+#include <CGAL/Surface_mesh.h>
+#include <CGAL/Nef_polyhedron_3.h>
+#include <CGAL/boost/graph/generators.h>
+
+
+#include <iostream>
+typedef CGAL::Exact_predicates_exact_constructions_kernel K;
+typedef K::Point_3 Point_3;
+typedef CGAL::Surface_mesh<K::Point_3> Polygon_mesh;
+
+typedef CGAL::Nef_polyhedron_3<K> Nef_polyhedron;
+
+int main(int /* argc */, char** /* argv[] */)
+{
+  Point_3 p0(1,1,1), p1(2,1,1), p2(2,2,1), p3(1,2,1), p4(1,2,2), p5(1,1,2), p6(2,1,2), p7(2,2,2);
+  Point_3 q0(0,0,0), q1(3,0,0), q2(3,3,0), q3(0,3,0), q4(0,3,3), q5(0,0,3), q6(3,0,3), q7(3,3,3);
+
+    Polygon_mesh A1, A2;
+
+    make_hexahedron(p0, p1, p2, p3, p4, p5, p6, p7, A1);
+    make_hexahedron(q0, q1, q2, q3, q4, q5, q6, q7, A2);
+    Nef_polyhedron a1(A1), a2(A2);
+
+    assert(a1 < a2);
+    assert(a2 > a1);
+
+    return 0;
+}