Normal Computation

Functions to compute unit normals for individual/all vertices or faces.

Functions
template<typename PolygonMesh , typename NamedParameters = parameters::Default_named_parameters>
Vector_3	CGAL::Polygon_mesh_processing::compute_face_normal (typename boost::graph_traits< PolygonMesh >::face_descriptor f, const PolygonMesh &pmesh, const NamedParameters &np=parameters::default_values())
	computes the outward unit vector normal to face f. More...
template<typename PolygonMesh , typename Face_normal_map , typename NamedParameters = parameters::Default_named_parameters>
void	CGAL::Polygon_mesh_processing::compute_face_normals (const PolygonMesh &pmesh, Face_normal_map face_normals, const NamedParameters &np=parameters::default_values())
	computes the outward unit vector normal for all faces of the polygon mesh. More...
template<typename PolygonMesh , typename NamedParameters = parameters::Default_named_parameters>
Vector_3	CGAL::Polygon_mesh_processing::compute_vertex_normal (typename boost::graph_traits< PolygonMesh >::vertex_descriptor v, const PolygonMesh &pmesh, const NamedParameters &np=parameters::default_values())
	computes the unit normal at vertex v as a function of the normals of incident faces. More...
template<typename PolygonMesh , typename VertexNormalMap , typename NamedParameters = parameters::Default_named_parameters>
void	CGAL::Polygon_mesh_processing::compute_vertex_normals (const PolygonMesh &pmesh, VertexNormalMap vertex_normals, const NamedParameters &np=parameters::default_values())
	computes the outward unit vector normal for all vertices of the polygon mesh. More...
template<typename PolygonMesh , typename VertexNormalMap , typename FaceNormalMap , typename NamedParameters = parameters::Default_named_parameters>
void	CGAL::Polygon_mesh_processing::compute_normals (const PolygonMesh &pmesh, VertexNormalMap vertex_normals, FaceNormalMap face_normals, const NamedParameters &np=parameters::default_values())
	computes the outward unit vector normal for all vertices and faces of the polygon mesh. More...

Function Documentation

compute_face_normal()

template<typename PolygonMesh , typename NamedParameters = parameters::Default_named_parameters>

Vector_3 CGAL::Polygon_mesh_processing::compute_face_normal	(	typename boost::graph_traits< PolygonMesh >::face_descriptor	f,
		const PolygonMesh &	pmesh,
		const NamedParameters &	np = parameters::default_values()
	)

#include <CGAL/Polygon_mesh_processing/compute_normal.h>

computes the outward unit vector normal to face f.

Template Parameters

PolygonMesh	a model of FaceGraph
NamedParameters	a sequence of Named Parameters

Parameters

f	the face whose normal is computed
pmesh	the polygon mesh containing f
np	an optional sequence of Named Parameters among the ones listed below

Optional Named Parameters

vertex_point_map a property map associating points to the vertices of pmesh Type: a class model of ReadablePropertyMap with boost::graph_traits<PolygonMesh>::vertex_descriptor as key type and Point_3 as value type Default: boost::get(CGAL::vertex_point, pmesh) Extra: If this parameter is omitted, an internal property map for CGAL::vertex_point_t must be available in PolygonMesh.
geom_traits an instance of a geometric traits class Type: a class model of Kernel Default: a CGAL Kernel deduced from the point type, using CGAL::Kernel_traits Extra: The geometric traits class must be compatible with the vertex point type.

Returns

the computed normal. The return type is a 3D vector 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 pmesh.

Warning

This function involves a square root computation. If the field type (FT) of the traits does not support the sqrt() operation, the square root computation will be performed approximately.

See also

compute_face_normals()

compute_face_normals()

template<typename PolygonMesh , typename Face_normal_map , typename NamedParameters = parameters::Default_named_parameters>

void CGAL::Polygon_mesh_processing::compute_face_normals	(	const PolygonMesh &	pmesh,
		Face_normal_map	face_normals,
		const NamedParameters &	np = parameters::default_values()
	)

#include <CGAL/Polygon_mesh_processing/compute_normal.h>

computes the outward unit vector normal for all faces of the polygon mesh.

Template Parameters

PolygonMesh	a model of FaceGraph
Face_normal_map	a model of WritablePropertyMap with boost::graph_traits<PolygonMesh>::face_descriptor as key type and Kernel::Vector_3 as value type.

Parameters

pmesh	the polygon mesh
face_normals	the property map in which the normals are written
np	an optional sequence of Named Parameters among the ones listed below

Optional Named Parameters

vertex_point_map a property map associating points to the vertices of pmesh Type: a class model of ReadablePropertyMap with boost::graph_traits<PolygonMesh>::vertex_descriptor as key type and Point_3 as value type Default: boost::get(CGAL::vertex_point, pmesh) Extra: If this parameter is omitted, an internal property map for CGAL::vertex_point_t must be available in PolygonMesh.
geom_traits an instance of a geometric traits class Type: a class model of Kernel Default: a CGAL Kernel deduced from the point type, using CGAL::Kernel_traits Extra: The geometric traits class must be compatible with the vertex point type.

Warning

This function involves a square root computation. If the field type (FT) of the traits does not support the sqrt() operation, the square root computation will be performed approximately.

See also

compute_face_normal()

compute_normals()

template<typename PolygonMesh , typename VertexNormalMap , typename FaceNormalMap , typename NamedParameters = parameters::Default_named_parameters>

void CGAL::Polygon_mesh_processing::compute_normals	(	const PolygonMesh &	pmesh,
		VertexNormalMap	vertex_normals,
		FaceNormalMap	face_normals,
		const NamedParameters &	np = parameters::default_values()
	)

#include <CGAL/Polygon_mesh_processing/compute_normal.h>

computes the outward unit vector normal for all vertices and faces of the polygon mesh.

Template Parameters

PolygonMesh	a model of FaceListGraph
VertexNormalMap	a model of WritablePropertyMap with boost::graph_traits<PolygonMesh>::vertex_descriptor as key type and Kernel::Vector_3 as value type.
FaceNormalMap	a model of ReadWritePropertyMap with boost::graph_traits<PolygonMesh>::face_descriptor as key type and Kernel::Vector_3 as value type.

Parameters

pmesh	the polygon mesh
vertex_normals	the property map in which the vertex normals are written
face_normals	the property map in which the face normals are written
np	an optional sequence of Named Parameters among the ones listed below

Optional Named Parameters

vertex_point_map a property map associating points to the vertices of pmesh Type: a class model of ReadablePropertyMap with boost::graph_traits<PolygonMesh>::vertex_descriptor as key type and Point_3 as value type Default: boost::get(CGAL::vertex_point, pmesh) Extra: If this parameter is omitted, an internal property map for CGAL::vertex_point_t must be available in PolygonMesh.
geom_traits an instance of a geometric traits class Type: a class model of Kernel Default: a CGAL Kernel deduced from the point type, using CGAL::Kernel_traits Extra: The geometric traits class must be compatible with the vertex point type.

Warning

This function involves a square root computation. If the field type (FT) of the traits does not support the sqrt() operation, the square root computation will be performed approximately.

See also

compute_vertex_normals()

compute_face_normals()

Examples:

Polygon_mesh_processing/compute_normals_example.cpp, and Polygon_mesh_processing/compute_normals_example_Polyhedron.cpp.

compute_vertex_normal()

template<typename PolygonMesh , typename NamedParameters = parameters::Default_named_parameters>

Vector_3 CGAL::Polygon_mesh_processing::compute_vertex_normal	(	typename boost::graph_traits< PolygonMesh >::vertex_descriptor	v,
		const PolygonMesh &	pmesh,
		const NamedParameters &	np = parameters::default_values()
	)

#include <CGAL/Polygon_mesh_processing/compute_normal.h>

computes the unit normal at vertex v as a function of the normals of incident faces.

The implementation is inspired by Aubry et al. "On the most 'normal' normal" [2], which aims to compute a normal that maximises the visibility to the incident faces. If such normal does not exist or if the optimization process fails to find it, a fallback normal is computed as a sine-weighted sum of the normals of the incident faces.

Note

The function compute_vertex_normals() should be preferred if normals are intended to be computed at all vertices of the graph.

Template Parameters

PolygonMesh

a model of FaceGraph

Parameters

v	the vertex whose normal is computed
pmesh	the polygon mesh containing v
np	an optional sequence of Named Parameters among the ones listed below

Optional Named Parameters

vertex_point_map a property map associating points to the vertices of pmesh Type: a class model of ReadablePropertyMap with boost::graph_traits<PolygonMesh>::vertex_descriptor as key type and Point_3 as value type Default: boost::get(CGAL::vertex_point, pmesh) Extra: If this parameter is omitted, an internal property map for CGAL::vertex_point_t must be available in PolygonMesh.
geom_traits an instance of a geometric traits class Type: a class model of Kernel Default: a CGAL Kernel deduced from the point type, using CGAL::Kernel_traits Extra: The geometric traits class must be compatible with the vertex point type.

Returns

the computed normal. The return type is a 3D vector type. It is either deduced from the geom_traits Named Parameters if provided, or the geometric traits class deduced from the point property map of pmesh.

Warning

This function involves a square root computation. If the field type (FT) of the traits does not support the sqrt() operation, the square root computation will be performed approximately.

See also

compute_vertex_normals()

compute_vertex_normals()

template<typename PolygonMesh , typename VertexNormalMap , typename NamedParameters = parameters::Default_named_parameters>

void CGAL::Polygon_mesh_processing::compute_vertex_normals	(	const PolygonMesh &	pmesh,
		VertexNormalMap	vertex_normals,
		const NamedParameters &	np = parameters::default_values()
	)

#include <CGAL/Polygon_mesh_processing/compute_normal.h>

computes the outward unit vector normal for all vertices of the polygon mesh.

Template Parameters

PolygonMesh	a model of FaceListGraph
VertexNormalMap	a model of WritablePropertyMap with boost::graph_traits<PolygonMesh>::vertex_descriptor as key type and the return type of compute_vertex_normal() as value type.

Parameters

pmesh	the polygon mesh
vertex_normals	the property map in which the normals are written
np	an optional sequence of Named Parameters among the ones listed below

Optional Named Parameters

vertex_point_map a property map associating points to the vertices of pmesh Type: a class model of ReadablePropertyMap with boost::graph_traits<PolygonMesh>::vertex_descriptor as key type and Point_3 as value type Default: boost::get(CGAL::vertex_point, pmesh) Extra: If this parameter is omitted, an internal property map for CGAL::vertex_point_t must be available in PolygonMesh.
geom_traits an instance of a geometric traits class Type: a class model of Kernel Default: a CGAL Kernel deduced from the point type, using CGAL::Kernel_traits Extra: The geometric traits class must be compatible with the vertex point type.

Warning

This function involves a square root computation. If the field type (FT) of the traits does not support the sqrt() operation, the square root computation will be performed approximately.

See also

compute_vertex_normal()

Examples:

Polygon_mesh_processing/extrude.cpp.