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CGAL 5.0.3 - Polygon Mesh Processing
Functions
Connected Components
Polygon Mesh Processing Reference

Two faces are in the same connected component if there is a path of adjacent faces such that all edges between two consecutive faces of the path are not marked as constrained.

Functions

template<typename PolygonMesh , typename FaceOutputIterator , typename NamedParameters >
FaceOutputIterator CGAL::Polygon_mesh_processing::connected_component (typename boost::graph_traits< PolygonMesh >::face_descriptor seed_face, const PolygonMesh &pmesh, FaceOutputIterator out, const NamedParameters &np)
 discovers all the faces in the same connected component as seed_face and records them in out. More...
 
template<typename PolygonMesh , typename FaceComponentMap , typename NamedParameters >
boost::property_traits< FaceComponentMap >::value_type CGAL::Polygon_mesh_processing::connected_components (const PolygonMesh &pmesh, FaceComponentMap fcm, const NamedParameters &np)
 computes for each face the index of the corresponding connected component. More...
 
template<typename PolygonMesh , typename NamedParameters >
std::size_t CGAL::Polygon_mesh_processing::keep_largest_connected_components (PolygonMesh &pmesh, std::size_t nb_components_to_keep, const NamedParameters &np)
 removes the small connected components and all isolated vertices. More...
 
template<typename PolygonMesh , typename ThresholdValueType , typename NamedParameters >
std::size_t CGAL::Polygon_mesh_processing::keep_large_connected_components (PolygonMesh &pmesh, const ThresholdValueType threshold_value, const NamedParameters &np)
 removes connected components whose size is (strictly) smaller than a given threshold value, where the size of a connected component is computed as the sum of the individual sizes of all the faces of the connected component. More...
 
template<typename PolygonMesh , typename ComponentRange , typename FaceComponentMap , typename NamedParameters >
void CGAL::Polygon_mesh_processing::keep_connected_components (PolygonMesh &pmesh, const ComponentRange &components_to_keep, const FaceComponentMap &fcm, const NamedParameters &np)
 keeps the connected components designated by theirs ids in components_to_keep, and removes the other connected components as well as all isolated vertices. More...
 
template<typename PolygonMesh , typename ComponentRange , typename FaceComponentMap , typename NamedParameters >
void CGAL::Polygon_mesh_processing::remove_connected_components (PolygonMesh &pmesh, const ComponentRange &components_to_remove, const FaceComponentMap &fcm, const NamedParameters &np)
 Removes in pmesh the connected components designated by theirs ids in components_to_remove as well as all isolated vertices. More...
 
template<typename PolygonMesh , typename FaceRange , typename NamedParameters >
void CGAL::Polygon_mesh_processing::remove_connected_components (PolygonMesh &pmesh, const FaceRange &components_to_remove, const NamedParameters &np)
 keeps the connected components not designated by the faces in components_to_remove, and removes the other connected components and all isolated vertices. More...
 
template<typename PolygonMesh , typename FaceRange , typename NamedParameters >
void CGAL::Polygon_mesh_processing::keep_connected_components (PolygonMesh &pmesh, const FaceRange &components_to_keep, const NamedParameters &np)
 keeps the connected components designated by the faces in components_to_keep, and removes the other connected components and all isolated vertices. More...
 

Function Documentation

◆ connected_component()

template<typename PolygonMesh , typename FaceOutputIterator , typename NamedParameters >
FaceOutputIterator CGAL::Polygon_mesh_processing::connected_component ( typename boost::graph_traits< PolygonMesh >::face_descriptor  seed_face,
const PolygonMesh &  pmesh,
FaceOutputIterator  out,
const NamedParameters &  np 
)

#include <CGAL/Polygon_mesh_processing/connected_components.h>

discovers all the faces in the same connected component as seed_face and records them in out.

seed_face will also be added in out.

Template Parameters
PolygonMesha model of FaceGraph
FaceOutputIteratora model of OutputIterator that accepts faces of type boost::graph_traits<PolygonMesh>::face_descriptor.
NamedParametersa sequence of Named Parameters
Parameters
seed_facea face of pmesh from which exploration starts to detect the connected component that contains it
pmeshthe polygon mesh
outthe output iterator that collects faces from the same connected component as seed_face
npoptional Named Parameters described below
Named Parameters
edge_is_constrained_mapa property map containing the constrained-or-not status of each edge of pmesh
Returns
the output iterator.
Examples:
Polygon_mesh_processing/connected_components_example.cpp.

◆ connected_components()

template<typename PolygonMesh , typename FaceComponentMap , typename NamedParameters >
boost::property_traits<FaceComponentMap>::value_type CGAL::Polygon_mesh_processing::connected_components ( const PolygonMesh &  pmesh,
FaceComponentMap  fcm,
const NamedParameters &  np 
)

#include <CGAL/Polygon_mesh_processing/connected_components.h>

computes for each face the index of the corresponding connected component.

A property map for CGAL::face_index_t must be either available as an internal property map to pmesh or provided as one of the Named Parameters.

Template Parameters
PolygonMesha model of FaceListGraph
FaceComponentMapa model of WritablePropertyMap with boost::graph_traits<PolygonMesh>::face_descriptor as key type and boost::graph_traits<PolygonMesh>::faces_size_type as value type.
NamedParametersa sequence of Named Parameters
Parameters
pmeshthe polygon mesh
fcmthe property map with indices of components associated to faces in pmesh
npoptional Named Parameters described below
Named Parameters
edge_is_constrained_mapa property map containing the constrained-or-not status of each edge of pmesh
face_index_mapa property map containing the index of each face of pmesh
Returns
the number of connected components.
Examples:
Polygon_mesh_processing/connected_components_example.cpp, and Polygon_mesh_processing/face_filtered_graph_example.cpp.

◆ keep_connected_components() [1/2]

template<typename PolygonMesh , typename ComponentRange , typename FaceComponentMap , typename NamedParameters >
void CGAL::Polygon_mesh_processing::keep_connected_components ( PolygonMesh &  pmesh,
const ComponentRange &  components_to_keep,
const FaceComponentMap &  fcm,
const NamedParameters &  np 
)

#include <CGAL/Polygon_mesh_processing/connected_components.h>

keeps the connected components designated by theirs ids in components_to_keep, and removes the other connected components as well as all isolated vertices.

The connected component id of a face is given by fcm.

Note
If the removal of the connected components makes pmesh a non-manifold surface, then the behavior of this function is undefined.

Property maps for CGAL::vertex_index_t must be either available as internal property map to pmesh or provided as Named Parameters.

Template Parameters
PolygonMesha model of FaceListGraph and MutableFaceGraph
NamedParametersa sequence of Named Parameters
ComponentRangea range of ids convertible to std::size
FaceComponentMapa model of ReadWritePropertyMap with boost::graph_traits<PolygonMesh>::face_descriptor as key type and boost::graph_traits<PolygonMesh>::faces_size_type as value type.
Parameters
components_to_keepthe range of ids of connected components to keep
pmeshthe polygon mesh
fcmthe property map with indices of components associated to faces in pmesh. After calling this function, the values of fcm are undefined.
npoptional Named Parameters described below
Named Parameters
vertex_index_mapa property map containing the index of each vertex of pmesh

◆ keep_connected_components() [2/2]

template<typename PolygonMesh , typename FaceRange , typename NamedParameters >
void CGAL::Polygon_mesh_processing::keep_connected_components ( PolygonMesh &  pmesh,
const FaceRange &  components_to_keep,
const NamedParameters &  np 
)

#include <CGAL/Polygon_mesh_processing/connected_components.h>

keeps the connected components designated by the faces in components_to_keep, and removes the other connected components and all isolated vertices.

Property maps for CGAL::face_index_t and CGAL::vertex_index_t must be either available as internal property maps to pmesh or provided as Named Parameters.

Note
If the removal of the connected components makes pmesh a non-manifold surface, then the behavior of this function is undefined.
Template Parameters
PolygonMesha model of FaceListGraph and MutableFaceGraph
NamedParametersa sequence of Named Parameters
FaceRangea range of boost::graph_traits<PolygonMesh>::face_descriptor indicating the connected components to be kept.
Parameters
pmeshthe polygon mesh
components_to_keepa face range, including one face or more on each component to be kept
npoptional Named Parameters, amongst those described below
Named Parameters
edge_is_constrained_mapa property map containing the constrained-or-not status of each edge of pmesh
face_index_mapa property map containing the index of each face of pmesh
vertex_index_mapa property map containing the index of each vertex of pmesh

◆ keep_large_connected_components()

template<typename PolygonMesh , typename ThresholdValueType , typename NamedParameters >
std::size_t CGAL::Polygon_mesh_processing::keep_large_connected_components ( PolygonMesh &  pmesh,
const ThresholdValueType  threshold_value,
const NamedParameters &  np 
)

#include <CGAL/Polygon_mesh_processing/connected_components.h>

removes connected components whose size is (strictly) smaller than a given threshold value, where the size of a connected component is computed as the sum of the individual sizes of all the faces of the connected component.

By default, the size of a face is 1 (and thus the size of a connected component is the number of faces it contains), but it is also possible to pass custom sizes, such as the area of the face.

Property maps for CGAL::face_index_t and CGAL::vertex_index_t must be either available as internal property maps to pmesh or provided as Named Parameters.

Template Parameters
PolygonMesha model of FaceListGraph and MutableFaceGraph
ThresholdValueTypethe type of the threshold value
NamedParametersa sequence of Named Parameters
Parameters
pmeshthe polygon mesh
threshold_valueany connected component with a size (strictly) smaller than this value will be discarded
npoptional Named Parameters, amongst those described below
Named Parameters
edge_is_constrained_mapa property map containing the constrained-or-not status of each edge of pmesh
face_index_mapa property map containing the index of each face of pmesh
vertex_index_mapa property map containing the index of each vertex of pmesh
face_size_mapa property map containing a size for each face of pmesh. The value type of this property map is chosen by the user, but must be constructible from 0 and support operator+=() and comparisons.
Precondition
If a face size property map is passed by the user, ThresholdValueType must be the same type as the value type of the property map. Otherwise, ThresholdValueType must be std::size_t.
Returns
the number of connected components removed (ignoring isolated vertices).
Examples:
Polygon_mesh_processing/connected_components_example.cpp.

◆ keep_largest_connected_components()

template<typename PolygonMesh , typename NamedParameters >
std::size_t CGAL::Polygon_mesh_processing::keep_largest_connected_components ( PolygonMesh &  pmesh,
std::size_t  nb_components_to_keep,
const NamedParameters &  np 
)

#include <CGAL/Polygon_mesh_processing/connected_components.h>

removes the small connected components and all isolated vertices.

Keep the nb_components_to_keep largest connected components, where the size of a connected component is computed as the sum of the individual sizes of all the faces of the connected component. By default, the size of a face is 1 (and thus the size of a connected component is the number of faces it contains), but it is also possible to pass custom sizes, such as the area of the face.

Property maps for CGAL::face_index_t and CGAL::vertex_index_t must be either available as internal property maps to pmesh or provided as Named Parameters.

Template Parameters
PolygonMesha model of FaceListGraph and MutableFaceGraph
NamedParametersa sequence of Named Parameters
Parameters
pmeshthe polygon mesh
nb_components_to_keepthe number of components to be kept
npoptional Named Parameters, amongst those described below
Named Parameters
edge_is_constrained_mapa property map containing the constrained-or-not status of each edge of pmesh
face_index_mapa property map containing the index of each face of pmesh
vertex_index_mapa property map containing the index of each vertex of pmesh
face_size_mapa property map containing a size for each face of pmesh. The value type of this property map is chosen by the user, but must be constructible from 0 and support operator+=() and comparisons.
Returns
the number of connected components removed (ignoring isolated vertices).
Examples:
Polygon_mesh_processing/connected_components_example.cpp.

◆ remove_connected_components() [1/2]

template<typename PolygonMesh , typename ComponentRange , typename FaceComponentMap , typename NamedParameters >
void CGAL::Polygon_mesh_processing::remove_connected_components ( PolygonMesh &  pmesh,
const ComponentRange &  components_to_remove,
const FaceComponentMap &  fcm,
const NamedParameters &  np 
)

#include <CGAL/Polygon_mesh_processing/connected_components.h>

Removes in pmesh the connected components designated by theirs ids in components_to_remove as well as all isolated vertices.

The connected component id of a face is given by fcm.

Note
If the removal of the connected components makes pmesh a non-manifold surface, then the behavior of this function is undefined.

Property maps for CGAL::vertex_index_t must be either available as internal property map to pmesh or provided as Named Parameters.

Template Parameters
PolygonMesha model of FaceListGraph and MutableFaceGraph
NamedParametersa sequence of Named Parameters
ComponentRangea range of ids convertible to std::size
FaceComponentMapa model of ReadWritePropertyMap with boost::graph_traits<PolygonMesh>::face_descriptor as key type and boost::graph_traits<PolygonMesh>::faces_size_type as value type.
Parameters
components_to_removethe range of ids of connected components to remove
pmeshthe polygon mesh
fcmthe property map with indices of components associated to faces in pmesh. After calling this function, the values of fcm are undefined.
npoptional Named Parameters described below
Named Parameters
vertex_index_mapa property map containing the index of each vertex of pmesh

◆ remove_connected_components() [2/2]

template<typename PolygonMesh , typename FaceRange , typename NamedParameters >
void CGAL::Polygon_mesh_processing::remove_connected_components ( PolygonMesh &  pmesh,
const FaceRange &  components_to_remove,
const NamedParameters &  np 
)

#include <CGAL/Polygon_mesh_processing/connected_components.h>

keeps the connected components not designated by the faces in components_to_remove, and removes the other connected components and all isolated vertices.

Property maps for CGAL::face_index_t and CGAL::vertex_index_t must be either available as internal property maps to pmesh or provided as Named Parameters.

Note
If the removal of the connected components makes pmesh a non-manifold surface, then the behavior of this function is undefined.
Template Parameters
PolygonMesha model of FaceListGraph and MutableFaceGraph
NamedParametersa sequence of Named Parameters
FaceRangea range of boost::graph_traits<PolygonMesh>::face_descriptor indicating the connected components to be removed.
Parameters
components_to_removea face range, including one face or more on each component to be removed
pmeshthe polygon mesh
npoptional Named Parameters, amongst those described below
Named Parameters
edge_is_constrained_mapa property map containing the constrained-or-not status of each edge of pmesh
face_index_mapa property map containing the index of each face of pmesh
vertex_index_mapa property map containing the index of each vertex of pmesh