CGAL 6.2 - Planar Parameterization of Triangulated Surface Meshes

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CGAL::Surface_mesh_parameterization::Orbifold_Tutte_parameterizer_3< SeamMesh, SolverTraits_ > Class Template Reference
Reference Manual » Surface Parameterization Methods

`#include <CGAL/Surface_mesh_parameterization/Orbifold_Tutte_parameterizer_3.h>`

## Definition

template<typename SeamMesh, typename SolverTraits_ = Default>
class CGAL::Surface_mesh_parameterization::Orbifold_Tutte_parameterizer_3< SeamMesh, SolverTraits_ >

The class `Orbifold_Tutte_parameterizer_3` implements Orbifold Tutte Planar Embeddings [1].

This is a borderless parameterization. A one-to-one mapping is guaranteed.

The main function of the class `Orbifold_Tutte_parameterizer_3` is `parameterize()`, to which the user provides a `Seam_mesh` with marked edges (the seams) and a set of vertices of the mesh (the cones). The choice of cones influences the resulting parameterization, but not the choice of the seam path between these cones.

Some helper functions related to the class `Orbifold_Tutte_parameterizer_3` (for example to read and compute paths between cones) can be found here .

The example orbifold.cpp shows how to select cones on the input mesh and automatically construct the seams and the cones on the `Seam_mesh`.

Attention
  The global function `CGAL::Surface_mesh_parameterization::parameterize()` cannot be used with this parameterizer. Users should use this class's member function `parameterize()` instead.

Template Parameters

  SeamMesh | must be a `Seam_mesh`, with underlying mesh any model of `FaceListGraph` and `HalfedgeListGraph`.
  SolverTraits_ | must be a model of `SparseLinearAlgebraTraits_d`. Default: If Eigen 3.1 (or greater) is available and `CGAL_EIGEN3_ENABLED` is defined, then an overload of `Eigen_solver_traits` is provided as default parameter: CGAL::Eigen_solver_traits< Eigen::SparseLU<Eigen_sparse_matrix<double>::EigenType> > CGAL::Eigen_solver_traits Moreover, if SuiteSparse solvers are available, which is greatly preferable for speed, then the default parameter is: CGAL::Eigen_solver_traits< Eigen::UmfPackLU<Eigen_sparse_matrix<double>::EigenType> >

See also
  Orbifold Helper Functions

## Public Types
typedef SolverTraits_ | Solver_traits
| Solver traits type.
typedef boost::graph_traits< SeamMesh >::halfedge_descriptor | halfedge_descriptor
| Mesh halfedge type.

## Public Member Functions
template<typename ConeMap , typename VertexIndexMap , typename VertexUVMap >
Error_code | parameterize (SeamMesh &mesh, halfedge_descriptor bhd, const ConeMap &cmap, VertexUVMap uvmap, VertexIndexMap vimap) const
| computes a one-to-one mapping from a triangular 3D surface mesh to a piece of the 2D space.
| Orbifold_Tutte_parameterizer_3 (const Orbifold_type orb_type=Square, const Weight_type weight_type=Cotangent)
| Constructor of the parameterizer.

## Constructor & Destructor Documentation

## ◆ Orbifold_Tutte_parameterizer_3()

template<typename SeamMesh , typename SolverTraits_ = Default>

CGAL::Surface_mesh_parameterization::Orbifold_Tutte_parameterizer_3< SeamMesh, SolverTraits_ >::Orbifold_Tutte_parameterizer_3 | ( | const Orbifold_type | orb_type = `Square`,
|  | const Weight_type | weight_type = `Cotangent`
| ) |  |

Constructor of the parameterizer.

The arguments allow to select the desired orbifold and weight types.

## Member Function Documentation

## ◆ parameterize()

template<typename SeamMesh , typename SolverTraits_ = Default>
template<typename ConeMap , typename VertexIndexMap , typename VertexUVMap >

Error_code CGAL::Surface_mesh_parameterization::Orbifold_Tutte_parameterizer_3< SeamMesh, SolverTraits_ >::parameterize | ( | SeamMesh & | mesh,
|  | halfedge_descriptor | bhd,
|  | const ConeMap & | cmap,
|  | VertexUVMap | uvmap,
|  | VertexIndexMap | vimap
| ) |  | const

computes a one-to-one mapping from a triangular 3D surface mesh to a piece of the 2D space.

The mapping is piecewise linear (linear in each triangle). The result is the (u,v) pair image of each vertex of the 3D surface.

Template Parameters

  ConeMap | must be a model of `AssociativeContainer` with key type `boost::graph_traits<Seam_mesh>::vertex_descriptor` and Cone_type as value type.
  VertexUVmap | must be a model of `ReadWritePropertyMap` with `boost::graph_traits<Seam_mesh>::vertex_descriptor` as key type and Point_2 (type deduced from `Seam_mesh` using `Kernel_traits`) as value type.
  VertexIndexMap | must be a model of `ReadablePropertyMap` with `boost::graph_traits<Seam_mesh>::vertex_descriptor` as key type and a unique integer as value type.

Parameters

  mesh | a `Seam_mesh` parameterized by any model of a `FaceListGraph` and `HalfedgeListGraph`
  bhd | a halfedge on the border of the seam mesh
  cmap | a mapping of the `vertex_descriptor`s of `mesh` that are cones to their respective Cone_type classification.
  uvmap | an instantiation of the class `VertexUVmap`.
  vimap | an instantiation of the class `VertexIndexMap`.

Precondition
  `mesh` must be a triangular mesh.
  The underlying mesh of `mesh` is a topological ball.
  The vertices must be indexed (vimap must be initialized).
  The cones are vertices of `mesh` and their number is adapted to the orbifold type (4 for types I, II or III and 6 for type IV).
  The seam edges form a set of segments that contains the different cones, and starts and ends at two different cones.
  The seam edges form a set of segments that is homotopic to a line. Specifically, the paths between cones must not self intersect or intersect other paths (see Figure below).

Figure 84.1 Invalid (left) and valid (right) seam paths. Seam edges are drawn in teal. Cones are marked in yellow and blue.