CGAL 5.1.3  2D Triangulation Data Structure

The concept TriangulationDSFaceBase_2
describes the requirements for the face base class of a CGAL::Triangulation_data_structure_2<Vb,Fb>
.
Note that if the CGAL::Triangulation_data_structure_2
is plugged into a triangulation class, the face base class may have additional geometric requirements depending on the triangulation class.
At the base level, (see Sections Software Design and The Default Triangulation Data Structure ), a face stores handles on its three vertices and on the three neighboring faces. The vertices and neighbors are indexed 0,1 and 2. Neighbor i
lies opposite to vertex i
.
Since the CGAL::Triangulation_data_structure_2
is the class which defines the handle types, the face base class has to be somehow parameterized by the triangulation data structure. But since the CGAL::Triangulation_data_structure_2
itself is parameterized by the face and vertex base classes, there is a cycle in the definition of these classes. In order to break the cycle, the base classes for faces and vertices which are plugged in to instantiate a CGAL::Triangulation_data_structure_2
use void
as triangulation data structure parameter. Then, the CGAL::Triangulation_data_structure_2
uses a rebind mechanism (similar to the one specified in std::allocator
) in order to plug itself as parameter in the face and vertex base classes. This mechanism requires that the base class provides a templated nested class Rebind_TDS
that itself provides the subtype Rebind_TDS::Other
which is the rebound version of the base class. This rebound base class is the class that the CGAL::Triangulation_data_structure_2
actually uses as a base class for the class CGAL::Triangulation_data_structure_2::Face
.
TriangulationDSVertexBase_2
CGAL::Triangulation_data_structure_2<Vb,Fb>
Types  
The concept  
template<typename TDS2 >  
using  Rebind_TDS = unspecified_type 
This template class has to define a type Rebind_TDS<TDS_2>::Other which is the rebound face base, where the CGAL::Triangulation_data_structure_2 is actually plugged in. More...  
typedef TriangulationDataStructure_2  Triangulation_data_structure 
typedef TriangulationDataStructure_2::Vertex_handle  Vertex_handle 
typedef TriangulationDataStructure_2::Face_handle  Face_handle 
Creation  
TriangulationDSFaceBase_2 ()  
default constructor.  
TriangulationDSFaceBase_2 (Vertex_handle v0, Vertex_handle v1, Vertex_handle v2)  
Initializes the vertices with v0, v1, v2 and the neighbors with Face_handle() .  
TriangulationDSFaceBase_2 (Vertex_handle v0, Vertex_handle v1, Vertex_handle v2, Face_handle n0, Face_handle n1, Face_handle n2)  
initializes the vertices with v0,v1, v2 and the neighbors with n0, n1, n2 .  
Access Functions  
int  dimension () 
returns the dimension.  
Orientation  
void  reorient () 
Changes the orientation of the face by exchanging vertex(0) with vertex(1) and neighbor(0) with neighbor(1) .  
void  ccw_permute () 
performs a counterclockwise permutation of the vertices and neighbors of the face.  
void  cw_permute () 
performs a clockwise permutation of the vertices and neighbors of the face.  
Checking  
bool  is_valid (bool verbose=false) const 
performs any required test on a face. More...  
Various  
These member functions are required by See the documentation of  
void *  for_compact_container () const 
void  for_compact_container (void *p) 
using TriangulationDSFaceBase_2::Rebind_TDS = unspecified_type 
This template class has to define a type Rebind_TDS<TDS_2>::Other
which is the rebound face base, where the CGAL::Triangulation_data_structure_2
is actually plugged in.
This type Other
will be the actual base of the class CGAL::Triangulation_data_structure_2::Face
.
bool TriangulationDSFaceBase_2::is_valid  (  bool  verbose = false  )  const 
performs any required test on a face.
If verbose
is set to true
, messages are printed to give a precise indication of the kind of invalidity encountered.