Meshing

Functions to triangulate faces, and to refine and fair regions of a polygon mesh.

Classes
struct	CGAL::Polygon_mesh_processing::Triangulate_faces::Default_visitor< PolygonMesh >
	Default new face visitor model of PMPTriangulateFaceVisitor. More...

Functions
template<class InputMesh , class OutputMesh , class BottomFunctor , class TopFunctor , class NamedParameters1 , class NamedParameters2 >
void	CGAL::Polygon_mesh_processing::extrude_mesh (const InputMesh &input, OutputMesh &output, const BottomFunctor &bot, const TopFunctor &top, const NamedParameters1 &np_in, const NamedParameters2 &np_out)
	performs a generalized extrusion of input and puts it in output. More...
template<class InputMesh , class OutputMesh , class NamedParameters1 , class NamedParameters2 >
void	CGAL::Polygon_mesh_processing::extrude_mesh (const InputMesh &input, OutputMesh &output, Vector_3 v, const NamedParameters1 &np_in, const NamedParameters2 &np_out)
	fills output with a closed mesh bounding the volume swept by input when translating its vertices by v. More...
template<typename TriangleMesh , typename VertexRange , typename NamedParameters >
bool	CGAL::Polygon_mesh_processing::fair (TriangleMesh &tmesh, const VertexRange &vertices, const NamedParameters &np)
	fairs a region on a triangle mesh. More...
template<typename VertexRange , typename TriangleMesh , typename NamedParameters >
void	CGAL::Polygon_mesh_processing::random_perturbation (VertexRange vertices, TriangleMesh &tmesh, const double &perturbation_max_size, const NamedParameters &np)
	randomly perturbs the locations of vertices of a triangulated surface mesh. More...
template<typename TriangleMesh , typename NamedParameters >
void	CGAL::Polygon_mesh_processing::random_perturbation (TriangleMesh &tmesh, const double &perturbation_max_size, const NamedParameters &np)
	same as above, but all non-border vertices of tmesh are perturbed.
template<typename TriangleMesh , typename FaceRange , typename FaceOutputIterator , typename VertexOutputIterator , typename NamedParameters >
std::pair< FaceOutputIterator, VertexOutputIterator >	CGAL::Polygon_mesh_processing::refine (TriangleMesh &tmesh, const FaceRange &faces, FaceOutputIterator faces_out, VertexOutputIterator vertices_out, const NamedParameters &np)
	refines a region of a triangle mesh More...
template<typename PolygonMesh , typename FaceRange , typename NamedParameters >
void	CGAL::Polygon_mesh_processing::isotropic_remeshing (const FaceRange &faces, const double &target_edge_length, PolygonMesh &pmesh, const NamedParameters &np)
	remeshes a triangulated region of a polygon mesh. More...
template<typename PolygonMesh , typename EdgeRange , typename NamedParameters >
void	CGAL::Polygon_mesh_processing::split_long_edges (const EdgeRange &edges, const double &max_length, PolygonMesh &pmesh, const NamedParameters &np)
	splits the edges listed in edges into sub-edges that are not longer than the given threshold max_length. More...
template<typename TriangleMesh , typename FaceRange , typename NamedParameters >
void	CGAL::Polygon_mesh_processing::smooth_mesh (const FaceRange &faces, TriangleMesh &tmesh, const NamedParameters &np)
	smooths a triangulated region of a polygon mesh. More...
template<typename TriangleMesh , typename FaceRange , typename NamedParameters >
void	CGAL::Polygon_mesh_processing::smooth_shape (const FaceRange &faces, TriangleMesh &tmesh, const double time, const NamedParameters &np)
	smooths the overall shape of the mesh by using the mean curvature flow. More...
template<typename PolygonMesh , typename NamedParameters >
bool	CGAL::Polygon_mesh_processing::triangulate_face (typename boost::graph_traits< PolygonMesh >::face_descriptor f, PolygonMesh &pmesh, const NamedParameters &np)
	triangulates a single face of a polygon mesh. More...
template<typename FaceRange , typename PolygonMesh , typename NamedParameters >
bool	CGAL::Polygon_mesh_processing::triangulate_faces (FaceRange face_range, PolygonMesh &pmesh, const NamedParameters &np)
	triangulates given faces of a polygon mesh. More...
template<typename PolygonMesh , typename NamedParameters >
bool	CGAL::Polygon_mesh_processing::triangulate_faces (PolygonMesh &pmesh, const NamedParameters &np)
	triangulates all faces of a polygon mesh. More...

Function Documentation

extrude_mesh() [1/2]

template<class InputMesh , class OutputMesh , class BottomFunctor , class TopFunctor , class NamedParameters1 , class NamedParameters2 >

void CGAL::Polygon_mesh_processing::extrude_mesh	(	const InputMesh &	input,
		OutputMesh &	output,
		const BottomFunctor &	bot,
		const TopFunctor &	top,
		const NamedParameters1 &	np_in,
		const NamedParameters2 &	np_out
	)

#include <CGAL/Polygon_mesh_processing/extrude.h>

performs a generalized extrusion of input and puts it in output.

This function extrudes the open surface mesh input and puts the result in output. The mesh generated is a closed surface mesh with a bottom and top part, both having the same graph combinatorics as input (except that the orientation of the faces of the bottom part is reversed). The bottom and the top parts are connected by a triangle strip between boundary cycles. The coordinates of the points associated to the vertices of the bottom and top part are first initialized to the same value as the corresponding vertices of input. Then for each vertex, a call to bot and top is done for the vertices of the bottom part and the top part, respectively.

Attention

output may be self intersecting.

Template Parameters

InputMesh	a model of FaceListGraph
OutputMesh	a model of FaceListGraph and MutableFaceGraph
NamedParameters1	a sequence of Named Parameters for InputMesh
NamedParameters2	a sequence of Named Parameters for OutputMesh
BottomFunctor	a functor providing void operator()`(boost::graph_traits<InputMesh>::vertex_descriptor input_v,boost::graph_traits<OutputMesh>::vertex_descriptor output_v) where output_v is the copy of input_v from input into the bottom part of output.
TopFunctor	a functor providing a similar operator() as BottomFunctor.

Parameters

input	an open surface mesh to extrude.
output	a surface mesh that will contain the result of the extrusion.
bot	functor that will transform all points copied from input in order to shape the bottom part of the extrusion.
top	functor that will transform all points copied from input in order to shape the top part of the extrusion.
np_in	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 input Type: a class model of ReadablePropertyMap with boost::graph_traits<InputMesh>::vertex_descriptor as key type and Point_3 as value type Default: boost::get(CGAL::vertex_point, input) Extra: If this parameter is omitted, an internal property map for CGAL::vertex_point_t should be available for the vertices of input.

Parameters

np_out

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 ouput Type: a class model of ReadWritePropertyMap with boost::graph_traits<OutputMesh>::vertex_descriptor as key type and Point_3 as value type Default: boost::get(CGAL::vertex_point, ouput) Extra: If this parameter is omitted, an internal property map for CGAL::vertex_point_t should be available for the vertices of ouput.

extrude_mesh() [2/2]

template<class InputMesh , class OutputMesh , class NamedParameters1 , class NamedParameters2 >

void CGAL::Polygon_mesh_processing::extrude_mesh	(	const InputMesh &	input,
		OutputMesh &	output,
		Vector_3	v,
		const NamedParameters1 &	np_in,
		const NamedParameters2 &	np_out
	)

#include <CGAL/Polygon_mesh_processing/extrude.h>

fills output with a closed mesh bounding the volume swept by input when translating its vertices by v.

The mesh is oriented so that the faces corresponding to input in output have the same orientation.

Attention

output may be self intersecting.

Template Parameters

InputMesh	a model of the concept FaceListGraph
OutputMesh	a model of the concept FaceListGraph and MutableFaceGraph
Vector_3	vector type from the same CGAL kernel as the point of the vertex point map used for OutputMesh.
NamedParameters1	a sequence of Named Parameters for InputMesh
NamedParameters2	a sequence of Named Parameters for OutputMesh

Parameters

input	an open surface mesh to extrude.
output	a surface mesh that will contain the result of the extrusion.
v	the vector defining the direction of the extrusion
np_in	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 input Type: a class model of ReadablePropertyMap with boost::graph_traits<InputMesh>::vertex_descriptor as key type and Point_3 as value type Default: boost::get(CGAL::vertex_point, input) Extra: If this parameter is omitted, an internal property map for CGAL::vertex_point_t should be available for the vertices of input.

Parameters

np_out

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 output Type: a class model of ReadWritePropertyMap with boost::graph_traits<OutputMesh>::vertex_descriptor as key type and Point_3 as value type Default: boost::get(CGAL::vertex_point, output) Extra: If this parameter is omitted, an internal property map for CGAL::vertex_point_t should be available for the vertices of output.

fair()

template<typename TriangleMesh , typename VertexRange , typename NamedParameters >

bool CGAL::Polygon_mesh_processing::fair	(	TriangleMesh &	tmesh,
		const VertexRange &	vertices,
		const NamedParameters &	np
	)

#include <CGAL/Polygon_mesh_processing/fair.h>

fairs a region on a triangle mesh.

The points of the selected vertices are relocated to yield an as-smooth-as-possible surface patch, based on solving a linear bi-Laplacian system with boundary constraints, described in [3]. The optional parameter fairing_continuity gives the ability to control the tangential continuity C ⁿ of the output mesh.

The region described by vertices might contain multiple disconnected components. Note that the mesh connectivity is not altered in any way, only vertex locations get updated.

Fairing might fail if fixed vertices, which are used as boundary conditions, do not suffice to solve constructed linear system.

Note that if the vertex range to which fairing is applied contains all the vertices of the triangle mesh, fairing does not fail, but the mesh gets shrinked to CGAL::ORIGIN.

Template Parameters

TriangleMesh	a model of FaceGraph and MutableFaceGraph
VertexRange	a range of vertex descriptors of TriangleMesh, model of Range. Its iterator type is InputIterator.
NamedParameters	a sequence of Named Parameters

Parameters

tmesh	the triangle mesh with patches to be faired
vertices	the vertices of the patches to be faired (the positions of only those vertices will be changed)
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 tmesh Type: a class model of ReadablePropertyMap with boost::graph_traits<TriangleMesh>::vertex_descriptor as key type and Point_3 as value type Default: boost::get(CGAL::vertex_point, tmesh) Extra: If this parameter is omitted, an internal property map for CGAL::vertex_point_t should be available for the vertices of tmesh.
fairing_continuity A value controling the tangential continuity of the output surface patch. The possible values are 0, 1 and 2, refering to the C0, C1 and C2 continuity. Type: unsigned int Default: 1 Extra: The larger fairing_continuity gets, the more fixed vertices are required.
sparse_linear_solver an instance of the sparse linear solver used for fairing Type: a class model of SparseLinearAlgebraWithFactorTraits_d Default: If Eigen 3.2 (or greater) is available and CGAL_EIGEN3_ENABLED is defined, then the following overload of Eigen_solver_traits is provided as default value: CGAL::Eigen_solver_traits<Eigen::SparseLU<CGAL::Eigen_sparse_matrix<double>::EigenType, Eigen::COLAMDOrdering<int> > >

Returns

true if fairing is successful, otherwise no vertices are relocated

Precondition

is_triangle_mesh(tmesh)

Warning

This function involves linear algebra, that is computed using a non-exact floating-point arithmetic.

Examples:

Polygon_mesh_processing/refine_fair_example.cpp.

isotropic_remeshing()

template<typename PolygonMesh , typename FaceRange , typename NamedParameters >

void CGAL::Polygon_mesh_processing::isotropic_remeshing	(	const FaceRange &	faces,
		const double &	target_edge_length,
		PolygonMesh &	pmesh,
		const NamedParameters &	np
	)

#include <CGAL/Polygon_mesh_processing/remesh.h>

remeshes a triangulated region of a polygon mesh.

This operation sequentially performs edge splits, edge collapses, edge flips, tangential relaxation and projection to the initial surface to generate a smooth mesh with a prescribed edge length.

Template Parameters

PolygonMesh	model of MutableFaceGraph. The descriptor types boost::graph_traits<PolygonMesh>::face_descriptor and boost::graph_traits<PolygonMesh>::halfedge_descriptor must be models of Hashable.
FaceRange	range of boost::graph_traits<PolygonMesh>::face_descriptor, model of Range. Its iterator type is ForwardIterator.
NamedParameters	a sequence of Named Parameters

Parameters

pmesh	a polygon mesh with triangulated surface patches to be remeshed
faces	the range of triangular faces defining one or several surface patches to be remeshed
target_edge_length	the edge length that is targeted in the remeshed patch. If 0 is passed then only the edge-flip, tangential relaxation, and projection steps will be done.
np	an optional sequence of Named Parameters among the ones listed below

Precondition

if constraints protection is activated, the constrained edges must not be longer than 4/3*target_edge_length

Optional Named Parameters

vertex_point_map a property map associating points to the vertices of pmesh Type: a class model of ReadWritePropertyMap 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. Extra: Exact constructions kernels are not supported by this function.
face_index_map a property map associating to each face of pmesh a unique index between 0 and num_faces(pmesh) - 1 Type: a class model of ReadablePropertyMap with boost::graph_traits<PolygonMesh>::face_descriptor as key type and std::size_t as value type Default: an automatically indexed internal map
number_of_iterations the number of iterations for the sequence of atomic operations performed (listed in the above description) Type: unsigned int Default: 1
edge_is_constrained_map a property map containing the constrained-or-not status of each edge of pmesh Type: a class model of ReadWritePropertyMap with boost::graph_traits<PolygonMesh>::edge_descriptor as key type and bool as value type. It must be default constructible. Default: a default property map where no edge is constrained Extra: A constrained edge can be split or collapsed, but not flipped, nor its endpoints moved by smoothing. Extra: Sub-edges generated by splitting are set to be constrained. Extra: Patch boundary edges (i.e. incident to only one face in the range) are always considered as constrained edges.
vertex_is_constrained_map a property map containing the constrained-or-not status of each vertex of pmesh. Type: a class model of ReadWritePropertyMap with boost::graph_traits<PolygonMesh>::vertex_descriptor as key type and bool as value type. It must be default constructible. Default: a default property map where no vertex is constrained Extra: A constrained vertex cannot be modified during remeshing.
protect_constraints If true, the edges set as constrained in edge_is_constrained_map (or by default the boundary edges) are not split nor collapsed during remeshing. Type: Boolean Default: false Extra: Note that around constrained edges that have their length higher than twice target_edge_length, remeshing will fail to provide good quality results. It can even fail to terminate because of cascading vertex insertions.
collapse_constraints If true, the edges set as constrained in edge_is_constrained_map (or by default the boundary edges) are collapsed during remeshing. Type: Boolean Default: true Extra: This value is ignored if protect_constraints is true.
face_patch_map a property map with the patch id's associated to the faces of faces Type: a class model of ReadWritePropertyMap with boost::graph_traits<PolygonMesh>::face_descriptor as key type and the desired property, model of CopyConstructible as value type. Default: a default property map where each face is associated with the ID of the connected component it belongs to. Connected components are computed with respect to the constrained edges listed in the property map edge_is_constrained_map Extra: The map is updated during the remeshing process while new faces are created.
number_of_relaxation_steps the number of iterations of tangential relaxation that are performed at each iteration of the remeshing process Type: unsigned int Default: 1
relax_constraints If true, the end vertices of the edges set as constrained in edge_is_constrained_map and boundary edges move along the constrained polylines they belong to.} Type: Boolean Default: false
do_project whether vertices should be reprojected on the input surface after creation or displacement Type: Boolean Default: true
projection_functor A function object used to project input vertices (moved by the smoothing) and created vertices Type: Unary functor that provides Point_3 operator()(vertex_descriptor), Point_3 being the value type of the vertex point map. Default: If not provided, vertices are projected on the input surface mesh.

See also

split_long_edges()

Examples:

Polygon_mesh_processing/corefinement_difference_remeshed.cpp, Polygon_mesh_processing/hausdorff_distance_remeshing_example.cpp, and Polygon_mesh_processing/isotropic_remeshing_example.cpp.

random_perturbation()

template<typename VertexRange , typename TriangleMesh , typename NamedParameters >

void CGAL::Polygon_mesh_processing::random_perturbation	(	VertexRange	vertices,
		TriangleMesh &	tmesh,
		const double &	perturbation_max_size,
		const NamedParameters &	np
	)

#include <CGAL/Polygon_mesh_processing/random_perturbation.h>

randomly perturbs the locations of vertices of a triangulated surface mesh.

By default, the vertices are re-projected onto the input surface after perturbation. Note that no geometric checks are done after the perturbation (face orientation might become incorrect and self-intersections might be introduced).

Template Parameters

VertexRange	model of Range, holding vertices of type boost::graph_traits<TriangleMesh>::vertex_descriptor. Its iterator type is ForwardIterator.
TriangleMesh	model of MutableFaceGraph.
NamedParameters	a sequence of Named Parameters

Parameters

vertices	the range of vertices to be perturbed
tmesh	the triangulated surface mesh
perturbation_max_size	the maximal length of moves that can be applied to vertices of tmesh.
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 tmesh Type: a class model of ReadWritePropertyMap with boost::graph_traits<TriangleMesh>::vertex_descriptor as key type and Point_3 as value type Default: boost::get(CGAL::vertex_point, tmesh)
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.
vertex_is_constrained_map a property map containing the constrained-or-not status of each vertex of tmesh Type: a class model of ReadWritePropertyMap with boost::graph_traits<TriangleMesh>::vertex_descriptor as key type and bool as value type. It must be default constructible. Default: a default property map where no vertex is constrained Extra: A constrained vertex cannot be modified at all during perturbation
do_project indicates whether vertices are reprojected on the input surface after their coordinates random perturbation Type: Boolean Default: true
random_seed a value to seed the random number generator, and make the perturbation deterministic Type: unsigned int Default: unsigned int(-1)

refine()

template<typename TriangleMesh , typename FaceRange , typename FaceOutputIterator , typename VertexOutputIterator , typename NamedParameters >

std::pair<FaceOutputIterator, VertexOutputIterator> CGAL::Polygon_mesh_processing::refine	(	TriangleMesh &	tmesh,
		const FaceRange &	faces,
		FaceOutputIterator	faces_out,
		VertexOutputIterator	vertices_out,
		const NamedParameters &	np
	)

#include <CGAL/Polygon_mesh_processing/refine.h>

refines a region of a triangle mesh

Template Parameters

TriangleMesh	model of MutableFaceGraph
FaceRange	range of face descriptors, model of Range. Its iterator type is InputIterator.
FaceOutputIterator	model of OutputIterator holding boost::graph_traits<TriangleMesh>::face_descriptor for patch faces
VertexOutputIterator	model of OutputIterator holding boost::graph_traits<TriangleMesh>::vertex_descriptor for patch vertices
NamedParameters	a sequence of Named Parameters

Parameters

tmesh	triangle mesh with patches to be refined
faces	the range of faces defining the patches to refine
faces_out	output iterator into which descriptors of new faces are recorded
vertices_out	output iterator into which descriptors of new vertices are recorded
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 tmesh Type: a class model of ReadWritePropertyMap with boost::graph_traits<TriangleMesh>::vertex_descriptor as key type and Point_3 as value type Default: boost::get(CGAL::vertex_point, tmesh) Extra: If this parameter is omitted, an internal property map for CGAL::vertex_point_t must be available in TriangleMesh.
density_control_factor a factor to control density of the output mesh, where larger values lead to denser refinements Type: double Default: $\sqrt{2}$ Extra: The density of vertices of faces_out is this factor times higher than the vertices of faces.

Returns

pair of faces_out and vertices_out

Precondition

is_triangle_mesh(tmesh)

Examples:

Polygon_mesh_processing/refine_fair_example.cpp.

smooth_mesh()

template<typename TriangleMesh , typename FaceRange , typename NamedParameters >

void CGAL::Polygon_mesh_processing::smooth_mesh	(	const FaceRange &	faces,
		TriangleMesh &	tmesh,
		const NamedParameters &	np
	)

#include <CGAL/Polygon_mesh_processing/smooth_mesh.h>

smooths a triangulated region of a polygon mesh.

This function attempts to make the triangle angle and area distributions as uniform as possible by moving (non-constrained) vertices.

Angle-based smoothing does not change the combinatorial information of the mesh. Area-based smoothing might change the combinatorial information, unless specified otherwise. It is also possible to make the smoothing algorithm "safer" by rejecting moves that, when applied, would worsen the quality of the mesh, e.g. that would decrease the value of the smallest angle around a vertex or create self-intersections.

Optionally, the points are reprojected after each iteration.

Template Parameters

TriangleMesh	model of MutableFaceGraph.
FaceRange	range of boost::graph_traits<TriangleMesh>::face_descriptor, model of Range. Its iterator type is ForwardIterator.
NamedParameters	a sequence of Named Parameters

Parameters

tmesh	a polygon mesh with triangulated surface patches to be smoothed.
faces	the range of triangular faces defining one or several surface patches to be smoothed.
np	an optional sequence of Named Parameters among the ones listed below

Optional Named Parameters

number_of_iterations the number of iterations for the sequence of the smoothing iterations performed Type: unsigned int Default: 1
use_angle_smoothing value to indicate whether angle-based smoothing should be used Type: Boolean Default: true
use_area_smoothing value to indicate whether area-based smoothing should be used Type: Boolean Default: true
vertex_point_map a property map associating points to the vertices of tmesh Type: a class model of ReadWritePropertyMap with boost::graph_traits<TriangleMesh>::vertex_descriptor as key type and Point_3 as value type Default: boost::get(CGAL::vertex_point, tmesh) Extra: If this parameter is omitted, an internal property map for CGAL::vertex_point_t must be available in TriangleMesh.
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.
use_safety_constraints If true, vertex moves that would worsen the mesh are ignored. Type: Boolean Default: false
use_Delaunay_flips If true, area-based smoothing will be completed by a phase of Delaunay-based edge-flips to prevent the creation of elongated triangles. Type: Boolean Default: true
do_project If true, points are projected onto the initial surface after each iteration. Type: Boolean Default: true
vertex_is_constrained_map a property map containing the constrained-or-not status of each vertex of tmesh. Type: a class model of ReadWritePropertyMap with boost::graph_traits<TriangleMesh>::vertex_descriptor as key type and bool as value type. It must be default constructible. Default: a default property map where no vertex is constrained Extra: A constrained vertex cannot be modified at all during smoothing.
edge_is_constrained_map a property map containing the constrained-or-not status of each edge of tmesh. Type: a class model of ReadWritePropertyMap with boost::graph_traits<TriangleMesh>::edge_descriptor as key type and bool as value type. It must be default constructible. Default: a default property map where no edge is constrained Extra: A constrained edge cannot be modified at all during smoothing.

Warning

The third party library Ceres is required to use area-based smoothing.

Precondition

tmesh does not contain any degenerate faces

Examples:

Polygon_mesh_processing/mesh_smoothing_example.cpp.

smooth_shape()

template<typename TriangleMesh , typename FaceRange , typename NamedParameters >

void CGAL::Polygon_mesh_processing::smooth_shape	(	const FaceRange &	faces,
		TriangleMesh &	tmesh,
		const double	time,
		const NamedParameters &	np
	)

#include <CGAL/Polygon_mesh_processing/smooth_shape.h>

smooths the overall shape of the mesh by using the mean curvature flow.

The effect depends on the curvature of each area and on a time step which represents the amount by which vertices are allowed to move. The result conformally maps the initial surface to a sphere.

Template Parameters

TriangleMesh	model of MutableFaceGraph.
FaceRange	range of boost::graph_traits<TriangleMesh>::face_descriptor, model of Range. Its iterator type is ForwardIterator.
NamedParameters	a sequence of Named Parameters

Parameters

tmesh	a polygon mesh with triangulated surface patches to be smoothed.
faces	the range of triangular faces defining one or several surface patches to be smoothed.
time	a time step that corresponds to the speed by which the surface is smoothed. A larger time step results in faster convergence but details may be distorted to have a larger extent compared to more iterations with a smaller step. Typical values scale in the interval (1e-6, 1].
np	an optional sequence of Named Parameters among the ones listed below

Optional Named Parameters

number_of_iterations the number of iterations for the sequence of the smoothing iterations performed Type: unsigned int Default: 1
vertex_point_map a property map associating points to the vertices of tmesh Type: a class model of ReadWritePropertyMap with boost::graph_traits<TriangleMesh>::vertex_descriptor as key type and Point_3 as value type Default: boost::get(CGAL::vertex_point, tmesh) Extra: If this parameter is omitted, an internal property map for CGAL::vertex_point_t must be available in TriangleMesh.
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.
vertex_is_constrained_map a property map containing the constrained-or-not status of each vertex of tmesh. Type: a class model of ReadWritePropertyMap with boost::graph_traits<TriangleMesh>::vertex_descriptor as key type and bool as value type. It must be default constructible. Default: a default property map where no vertex is constrained Extra: A constrained vertex cannot be modified at all during smoothing.
sparse_linear_solver an instance of the sparse linear solver used for smoothing Type: a class model of SparseLinearAlgebraWithFactorTraits_d Default: if Eigen 3.2 (or greater) is available and CGAL_EIGEN3_ENABLED is defined, then the following overload of Eigen_solver_traits is provided as default value: CGAL::Eigen_solver_traits<Eigen::BiCGSTAB<CGAL::Eigen_sparse_matrix<double>::EigenType, Eigen::IncompleteLUT<double> > >

Warning

This function involves linear algebra, that is computed using a non-exact floating-point arithmetic.

Examples:

Polygon_mesh_processing/shape_smoothing_example.cpp.

split_long_edges()

template<typename PolygonMesh , typename EdgeRange , typename NamedParameters >

void CGAL::Polygon_mesh_processing::split_long_edges	(	const EdgeRange &	edges,
		const double &	max_length,
		PolygonMesh &	pmesh,
		const NamedParameters &	np
	)

#include <CGAL/Polygon_mesh_processing/remesh.h>

splits the edges listed in edges into sub-edges that are not longer than the given threshold max_length.

Note this function is useful to split constrained edges before calling isotropic_remeshing() with protection of constraints activated (to match the constrained edge length required by the remeshing algorithm to be guaranteed to terminate)

Template Parameters

PolygonMesh	model of MutableFaceGraph that has an internal property map for CGAL::vertex_point_t.
EdgeRange	range of boost::graph_traits<PolygonMesh>::edge_descriptor, model of Range. Its iterator type is InputIterator.
NamedParameters	a sequence of Named Parameters

Parameters

pmesh	a polygon mesh
edges	the range of edges to be split if they are longer than given threshold
max_length	the edge length above which an edge from edges is split into to sub-edges
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 ReadWritePropertyMap 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.
face_index_map a property map associating to each face of pmesh a unique index between 0 and num_faces(pmesh) - 1 Type: a class model of ReadablePropertyMap with boost::graph_traits<PolygonMesh>::face_descriptor as key type and std::size_t as value type Default: an automatically indexed internal map
edge_is_constrained_map a property map containing the constrained-or-not status of each edge of pmesh Type: a class model of ReadWritePropertyMap with boost::graph_traits<PolygonMesh>::edge_descriptor as key type and bool as value type. It must be default constructible. Default: a default property map where no edge is constrained Extra: A constrained edge can be split or collapsed, but not flipped, nor its endpoints moved by smoothing.

See also

isotropic_remeshing()

Examples:

Polygon_mesh_processing/isotropic_remeshing_example.cpp.

triangulate_face()

template<typename PolygonMesh , typename NamedParameters >

bool CGAL::Polygon_mesh_processing::triangulate_face	(	typename boost::graph_traits< PolygonMesh >::face_descriptor	f,
		PolygonMesh &	pmesh,
		const NamedParameters &	np
	)

#include <CGAL/Polygon_mesh_processing/triangulate_faces.h>

triangulates a single face of a polygon mesh.

This function depends on the package 2D Triangulation

Template Parameters

PolygonMesh	a model of FaceListGraph and MutableFaceGraph
NamedParameters	a sequence of Named Parameters

Parameters

f	face to be triangulated
pmesh	the polygon mesh to which the face to be triangulated belongs
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 ReadWritePropertyMap 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.
visitor a visitor that enables to track how faces are triangulated into subfaces Type: a class model of PMPTriangulateFaceVisitor Default: Triangulate_faces::Default_visitor<PolygonMesh> Extra: Note that the visitor will be copied, so it must not have any data member that does not have a reference-like type.

Returns

true if the face has been triangulated.

triangulate_faces() [1/2]

template<typename FaceRange , typename PolygonMesh , typename NamedParameters >

bool CGAL::Polygon_mesh_processing::triangulate_faces	(	FaceRange	face_range,
		PolygonMesh &	pmesh,
		const NamedParameters &	np
	)

#include <CGAL/Polygon_mesh_processing/triangulate_faces.h>

triangulates given faces of a polygon mesh.

This function depends on the package 2D Triangulation

Template Parameters

FaceRange	range of boost::graph_traits<PolygonMesh>::face_descriptor, model of Range. Its iterator type is InputIterator.
PolygonMesh	a model of FaceListGraph and MutableFaceGraph
NamedParameters	a sequence of Named Parameters

Parameters

face_range	the range of faces to be triangulated
pmesh	the polygon mesh to be triangulated
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 ReadWritePropertyMap 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.
visitor a visitor that enables to track how faces are triangulated into subfaces Type: a class model of PMPTriangulateFaceVisitor Default: Triangulate_faces::Default_visitor<PolygonMesh> Extra: Note that the visitor will be copied, so it must not have any data member that does not have a reference-like type. `

Returns

true if all the faces have been triangulated.

See also

triangulate_face()

Examples:

Polygon_mesh_processing/locate_example.cpp, Polygon_mesh_processing/triangulate_faces_example.cpp, and Polygon_mesh_processing/triangulate_faces_split_visitor_example.cpp.

triangulate_faces() [2/2]

template<typename PolygonMesh , typename NamedParameters >

bool CGAL::Polygon_mesh_processing::triangulate_faces	(	PolygonMesh &	pmesh,
		const NamedParameters &	np
	)

#include <CGAL/Polygon_mesh_processing/triangulate_faces.h>

triangulates all faces of a polygon mesh.

This function depends on the package 2D Triangulation

Template Parameters

PolygonMesh	a model of FaceListGraph and MutableFaceGraph
NamedParameters	a sequence of Named Parameters

Parameters

pmesh	the polygon mesh to be triangulated
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 ReadWritePropertyMap 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.
visitor a visitor that enables to track how faces are triangulated into subfaces Type: a class model of PMPTriangulateFaceVisitor Default: Triangulate_faces::Default_visitor<PolygonMesh> Extra: Note that the visitor will be copied, so it must not have any data member that does not have a reference-like type.

Returns

true if all the faces have been triangulated.

See also

triangulate_face()