BGL Named Parameters

The algorithms of the Bgl often have many parameters with default values that are appropriate for most cases. In general, when no special treatment is applied, the values of such parameters are passed as a sequence. Deviating from the default for a certain parameter requires the user to explicitly pass values for all preceding parameters. The solution to this problem is to first write a tag and then the parameter, which for Dijkstra's shortest path algorithm might look as follows:

std::vector<vertex_descriptor> p(num_vertices(g));
std::vector<int> d(num_vertices(g));
vertex_descriptor s = vertex(A, g);
dijkstra_shortest_paths(g, s, predecessor_map(&p[0]).distance_map(&d[0]));

In the Bgl manual, this is called named parameters. The named parameters in the example use the tags predecessor_map and distance_map and they are concatenated with the dot operator.

In the following, we assume that PolygonMesh is a model of the concept FaceGraph. Note that for some functions, the type might be more specific:

Here is the list of the named parameters available in this package:

vertex_point_map	is the property map with the points associated to the vertices of the polygon mesh. Type: a class model of ReadablePropertyMap with boost::graph_traits<PolygonMesh>::vertex_descriptor as key type and a CGAL point type as value type. Default: boost::get(CGAL::vertex_point, pmesh)
vertex_index_map	is the property map associating a unique index to each vertex of a polygon mesh g, between 0 and num_vertices(g)-1. If this parameter is not passed, internal machinery will create and initialize a vertex index property map, either using the internal property map if it exists or using an external map. The latter might result in - slightly - worsened performance in case of non-constant complexity for index access. Type: a class model of ReadablePropertyMap with boost::graph_traits<PolygonMesh>::vertex_descriptor as key type and the value type typename boost::property_traits<typename boost::property_map<PolygonMesh, CGAL::vertex_index_t>::type>::value_type Default: an initialized vertex index property map
halfedge_index_map	is the property map associating a unique index to each halfedge of a polygon mesh, between 0 and num_halfedges(g)-1. If this parameter is not passed, internal machinery will create and initialize a halfedge index property map, either using the internal property map if it exists or using an external map. The latter might result in - slightly - worsened performance in case of non-constant complexity for index access. Type: a class model of ReadablePropertyMap with boost::graph_traits<PolygonMesh>::halfedge_descriptor as key type and the value type: typename boost::property_traits<typename boost::property_map<PolygonMesh, CGAL::halfedge_index_t>::type>::value_type Default: an initialized halfedge index property map
edge_index_map	is the property map associating a unique index to each edge of a polygon mesh, between 0 and num_edges(g)-1. If this parameter is not passed, internal machinery will create and initialize a edge index property map, either using the internal property map if it exists or using an external map. The latter might result in - slightly - worsened performance in case of non-constant complexity for index access. Type: a class model of ReadablePropertyMap with boost::graph_traits<PolygonMesh>::edge_descriptor as key type and the value type: typename boost::property_traits<typename boost::property_map<PolygonMesh, CGAL::edge_index_t>::type>::value_type Default: an initialized edge index property map
face_index_map	is the property map associating a unique index to each face of a polygon mesh, between 0 and num_faces(g)-1. If this parameter is not passed, internal machinery will create and initialize a face index property map, either using the internal property map if it exists or using an external map. The latter might result in - slightly - worsened performance in case of non-constant complexity for index access. Type: a class model of ReadablePropertyMap with boost::graph_traits<PolygonMesh>::face_descriptor as key type and the value type: typename boost::property_traits<typename boost::property_map<PolygonMesh, CGAL::face_index_t>::type>::value_type Default: an initialized face index property map
edge_is_constrained_map	is the property map containing information about edges of the input polygon mesh being marked or not. Type: a class model of ReadWritePropertyMap with boost::graph_traits<PolygonMesh>::edge_descriptor as key type and bool as value type. It should be default constructible. Default: a default property map where no edge is constrained
use_binary_mode	is a Boolean indicating whether the binary mode or the ASCII mode should be used when writing data into a stream. Type: bool Default: Function specific.
METIS_options	is a parameter used in partition_graph() and partition_dual_graph() to pass options to the METIS graph partitioner. The many options of METIS are not described here. Instead, users should refer to METIS' documentation. Type: an array of size METIS_NOPTIONS with value type idx_t (an integer type defined by METIS). Default: an array of size METIS_NOPTIONS with value type idx_t, initialized using the function METIS_SetDefaultOptions().
vertex_partition_id_map	is the property map storing for each vertex of the mesh the id of the subpart of the partition that has been assigned to this vertex. Type: a class model of ReadWritePropertyMap with boost::graph_traits<PolygonMesh>::vertex_descriptor as key type and int as value type. Default: None: this property map is used to store the partition IDs of the vertices as result of a partition algorithm; if it is not provided, this information is simply inaccessible.
face_partition_id_map	is the property map storing for each face of the mesh the id of the subpart of the partition that has been assigned to this face. Type: a class model of ReadWritePropertyMap with boost::graph_traits<PolygonMesh>::face_descriptor as key type and int as value type. Default: None: this property map is used to store the partition IDs of the faces as result of a partition algorithm; if it is not provided, this information is simply inaccessible.
vertex_to_vertex_output_iterator	is a model of OutputIterator accepting std::pair<vertex_descriptor, vertex_descriptor> A typical use case is mapping the vertices from a source mesh to its copy's after a copy_face_graph() operation. Type:a class model of OutputIterator accepting std::pair<boost::graph_traits<PolygonMesh>::vertex_descriptor, boost::graph_traits<PolygonMesh>::vertex_descriptor>. Default: Emptyset_iterator
halfedge_to_halfedge_output_iterator	is a model of OutputIterator accepting std::pair<halfedge_descriptor, halfedge_descriptor> A typical use case is mapping the halfedges from a source mesh to its copy's after a copy_face_graph() operation. Type:a class model of OutputIterator accepting std::pair<boost::graph_traits<PolygonMesh>::halfedge_descriptor, boost::graph_traits<PolygonMesh>::halfedge_descriptor>. Default: Emptyset_iterator
face_to_face_output_iterator	is a model of OutputIterator accepting std::pair<face_descriptor, face_descriptor> A typical use case is mapping the faces from a source mesh to its copy's after a copy_face_graph() operation. Type:a class model of OutputIterator accepting std::pair<boost::graph_traits<PolygonMesh>::face_descriptor, boost::graph_traits<PolygonMesh>::face_descriptor>. Default: Emptyset_iterator
vertex_to_vertex_map	is a property map storing for each vertex of a source mesh the corresponding vertex of another mesh. A typical use case is mapping the vertices from a source mesh to its copy's after a copy_face_graph() operation. Type:a class model of ReadWritePropertyMap with boost::graph_traits<PolygonMesh1>::vertex_descriptor as key type and boost::graph_traits<PolygonMesh2>::vertex_descriptor as value type. Default: None.
halfedge_to_halfedge_map	is a property map storing for each halfedge of a source mesh the corresponding halfedge of another mesh. A typical use case is mapping the vertices from a source mesh to its copy's after a copy_face_graph() operation. Type:a class model of ReadWritePropertyMap with boost::graph_traits<PolygonMesh1>::halfedge_descriptor as key type and boost::graph_traits<PolygonMesh2>::halfedge_descriptor as value type. Default: None.
face_to_face_map	is a property map storing for each face of a source mesh the corresponding face of another mesh. A typical use case is mapping the vertices from a source mesh to its copy's after a copy_face_graph() operation. Type:a class model of ReadWritePropertyMap with boost::graph_traits<PolygonMesh1>::face_descriptor as key type and boost::graph_traits<PolygonMesh2>::face_descriptor as value type. Default: None.
implementation_tag	tag used to select the implementation to be used among an algorithm-specific list. Type:a tag class Default: algorithm-specific.
prevent_unselection	Boolean used to indicate if selection can be only extended or if it can also be shrinked. Type: bool Default: false.
geom_traits	is the geometric traits instance used. Type: a Geometric traits class. Default: typename CGAL::Kernel_traits< typename boost::property_traits< typename boost::property_map<FaceGraph, CGAL::vertex_point_t>::type>::value_type>::Kernel