diff --git a/Polygon_mesh_processing/include/CGAL/Polygon_mesh_processing/orient_polygon_soup.h b/Polygon_mesh_processing/include/CGAL/Polygon_mesh_processing/orient_polygon_soup.h index 2ffc899b5490..de2bcab9c1c9 100644 --- a/Polygon_mesh_processing/include/CGAL/Polygon_mesh_processing/orient_polygon_soup.h +++ b/Polygon_mesh_processing/include/CGAL/Polygon_mesh_processing/orient_polygon_soup.h @@ -39,10 +39,10 @@ namespace CGAL { namespace Polygon_mesh_processing { /** \ingroup PMP_orientation_grp + * * Default visitor model of `PMPPolygonSoupOrientationVisitor`. * All of its functions have an empty body. This class can be used as a - * base class if only some of the functions of the concept require to be - * overridden. + * base class if only some of the functions of the concept will be overridden. */ struct Default_orientation_visitor{ void non_manifold_edge(std::size_t, std::size_t, std::size_t){} @@ -483,12 +483,22 @@ struct Polygon_soup_orienter * * \brief tries to consistently orient a soup of polygons in 3D space. * - * When it is not possible to produce a combinatorial manifold surface, + * The algorithm re-orients polygons such that the orientation + * of adjacent polygons is consistent. Note that the adjacency is + * defined in a combinatorial sense, i.e. two polygons are sharing + * an edge if and only if the endpoints of this edge are represented + * by the same point indices in both faces (possibly in a different order); + * it is not sufficient for the points to be geometrically identical. + * One may use `CGAL::Polygon_mesh_processing::merge_duplicate_points_in_polygon_soup()` + * to convert geometrical point equality into combinatorial point equality. + * + * When it is not possible to produce a combinatorial manifold surface + * (for example, if the polygon soup makes up a Möbius strip), * some points are duplicated. * Because a polygon soup does not have any connectivity (each point * has as many occurrences as the number of polygons it belongs to), * duplicating one point (or a pair of points) - * amounts to duplicate the polygon to which it belongs. + * amounts to duplicating the polygon to which it belongs. * * These points are either an endpoint of an edge incident to more * than two polygons, an endpoint of an edge between @@ -521,7 +531,7 @@ struct Polygon_soup_orienter * \cgalNamedParamsEnd * * @return `true` if the orientation operation succeeded. - * @return `false` if some points were duplicated, thus producing a self-intersecting polyhedron. + * @return `false` if some points were duplicated, thus producing a combinatorially manifold but self-intersecting polyhedron. * * @sa `orient_triangle_soup_with_reference_triangle_mesh()` */