Functions to detect sharp edges and surface patches of polygon meshes.

Functions
template<typename PolygonMesh , typename FT , typename EdgeIsFeatureMap , typename NamedParameters >
void	CGAL::Polygon_mesh_processing::detect_sharp_edges (PolygonMesh &pmesh, FT angle_in_deg, EdgeIsFeatureMap edge_is_feature_map, const NamedParameters &np)
	detects and marks the edges that are considered to be sharp with respect to the given angle bound. More...

template<typename PolygonMesh , typename PatchIdMap , typename VertexIncidentPatchesMap , typename EdgeIsFeatureMap >
void	CGAL::Polygon_mesh_processing::detect_vertex_incident_patches (PolygonMesh &pmesh, const PatchIdMap patch_id_map, VertexIncidentPatchesMap vertex_incident_patches_map, const EdgeIsFeatureMap edge_is_feature_map)
	collects the surface patches of the faces incident to each vertex of the input polygon mesh. More...

template<typename PolygonMesh , typename FT , typename EdgeIsFeatureMap , typename PatchIdMap , typename NamedParameters >
boost::graph_traits< PolygonMesh >::faces_size_type	CGAL::Polygon_mesh_processing::sharp_edges_segmentation (PolygonMesh &pmesh, FT angle_in_deg, EdgeIsFeatureMap edge_is_feature_map, PatchIdMap patch_id_map, const NamedParameters &np)
	This function calls successively `CGAL::Polygon_mesh_processing::detect_sharp_edges()`, `CGAL::Polygon_mesh_processing::connected_components()` and `CGAL::Polygon_mesh_processing::detect_vertex_incident_patches()` More...

Function Documentation

◆ detect_sharp_edges()

template<typename PolygonMesh , typename FT , typename EdgeIsFeatureMap , typename NamedParameters >

void CGAL::Polygon_mesh_processing::detect_sharp_edges	(	PolygonMesh &	pmesh,
		FT	angle_in_deg,
		EdgeIsFeatureMap	edge_is_feature_map,
		const NamedParameters &	np
	)

#include <CGAL/Polygon_mesh_processing/detect_features.h>

detects and marks the edges that are considered to be sharp with respect to the given angle bound.

angle_in_deg gives the maximum angle (in degrees) between the two normal vectors of adjacent triangles. For an edge of the input polygon mesh, if the angle between the two normal vectors of its incident facets is bigger than the given bound, then the edge is marked as being a feature edge.

Also computes the number of sharp edges incident to each vertex, if vertex_feature_degree_map is provided.

Template Parameters

PolygonMesh	a model of `HalfedgeListGraph`
FT	a number type. It is either deduced from the `geom_traits` Named Parameters if provided, or from the geometric traits class deduced from the point property map of `PolygonMesh`.
EdgeIsFeatureMap	a model of `ReadWritePropertyMap` with `boost::graph_traits<PolygonMesh>::edge_descriptor` as key type and `bool` as value type. It must be default constructible.
NamedParameters	a sequence of Named Parameters

Parameters

pmesh	the polygon mesh
angle_in_deg	the dihedral angle bound
edge_is_feature_map	the property map that will contain the sharp-or-not status of each edge of `pmesh`
np	optional Named Parameters, amongst those described below

Named Parameters

geom_traits	an instance of a geometric traits class, model of `Kernel`
vertex_feature_degree_map	a property map that will contain the number of adjacent feature edges for each vertex of `pmesh`

◆ detect_vertex_incident_patches()

template<typename PolygonMesh , typename PatchIdMap , typename VertexIncidentPatchesMap , typename EdgeIsFeatureMap >

void CGAL::Polygon_mesh_processing::detect_vertex_incident_patches	(	PolygonMesh &	pmesh,
		const PatchIdMap	patch_id_map,
		VertexIncidentPatchesMap	vertex_incident_patches_map,
		const EdgeIsFeatureMap	edge_is_feature_map
	)

#include <CGAL/Polygon_mesh_processing/detect_features.h>

collects the surface patches of the faces incident to each vertex of the input polygon mesh.

Template Parameters

PolygonMesh	a model of `HalfedgeListGraph`
PatchIdMap	a model of `ReadPropertyMap` with `boost::graph_traits<PolygonMesh>::face_descriptor` as key type and the desired patch id, model of `CopyConstructible` as value type.
VertexIncidentPatchesMap	a model of mutable `LvaluePropertyMap` with `boost::graph_traits<PolygonMesh>::vertex_descriptor` as key type. Its value type must be a container of `boost::property_traits<PatchIdMap>::value_type` and have a function `insert()`. A `std::set` or a `boost::unordered_set` are recommended, as a patch index may be inserted several times.
EdgeIsFeatureMap	a model of `ReadPropertyMap` with `boost::graph_traits<PolygonMesh>::edge_descriptor` as key type and `bool` as value type.

Parameters

pmesh	the polygon mesh
patch_id_map	the property map containing the surface patch ids for the faces of `pmesh`. It must be already filled.
vertex_incident_patches_map	a property map that will contain the patch ids of all the faces incident to each vertex of `pmesh`.
edge_is_feature_map	a filled property map that will contain the sharp-or-not status of each edge of `pmesh`

See also: CGAL::Polygon_mesh_processing::sharp_edges_segmentation()

◆ sharp_edges_segmentation()

template<typename PolygonMesh , typename FT , typename EdgeIsFeatureMap , typename PatchIdMap , typename NamedParameters >

boost::graph_traits<PolygonMesh>::faces_size_type CGAL::Polygon_mesh_processing::sharp_edges_segmentation	(	PolygonMesh &	pmesh,
		FT	angle_in_deg,
		EdgeIsFeatureMap	edge_is_feature_map,
		PatchIdMap	patch_id_map,
		const NamedParameters &	np
	)

#include <CGAL/Polygon_mesh_processing/detect_features.h>

This function calls successively CGAL::Polygon_mesh_processing::detect_sharp_edges(), CGAL::Polygon_mesh_processing::connected_components() and CGAL::Polygon_mesh_processing::detect_vertex_incident_patches()

It detects and marks the sharp edges of pmesh according to angle_in_deg. The sharp edges define a segmentation of pmesh, that is done by computing a surface patch id for each face.

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

PolygonMesh	a model of `FaceGraph`
FT	a number type. It is either deduced from the `geom_traits` Named Parameters if provided, or from the geometric traits class deduced from the point property map of `PolygonMesh`.
EdgeIsFeatureMap	a model of `ReadWritePropertyMap` with `boost::graph_traits<PolygonMesh>::edge_descriptor`
PatchIdMap	a model of `ReadWritePropertyMap` with `boost::graph_traits<PolygonMesh>::face_descriptor` as key type and the desired patch id, model of `CopyConstructible` as value type.
NamedParameters	a sequence of Named Parameters

Parameters

pmesh	the polygon mesh
angle_in_deg	the dihedral angle bound
edge_is_feature_map	the property map that will contain the sharp-or-not status of each edge of `pmesh`
patch_id_map	the property map that will contain the surface patch ids for the faces of `pmesh`.
np	optional Named Parameters, amongst those described below

Named Parameters

geom_traits	an instance of a geometric traits class, model of `Kernel`
vertex_feature_degree_map	a property map that will contain the number of adjacent feature edges for each vertex of `pmesh`
first_index	a `std::size_t` containing the index of the first surface patch of `pmesh`. The patches will be numbered on [first_index; first_index + num_patches], where num_patches is the number of surface patches
face_index_map	a property map containing the index of each face of `pmesh`
vertex_incident_patches_map	a property map that will contain the patch ids of all the faces incident to each vertex of `pmesh`.

Returns: the number of surface patches.

See also: CGAL::Polygon_mesh_processing::detect_sharp_edges(); CGAL::Polygon_mesh_processing::connected_components(); CGAL::Polygon_mesh_processing::detect_vertex_incident_patches()

Examples:: Polygon_mesh_processing/detect_features_example.cpp.