CGAL 6.1 - 3D Triangulation Data Structure

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TriangulationDSCellBase_3 Concept Reference
Reference Manual » Concepts

## Definition

Refines
  `TriangulationDataStructure_3::Cell`

The concept `TriangulationDSCellBase_3` describes the requirements for the cell base class of a `CGAL::Triangulation_data_structure_3<Vb,Cb>`.

Note that if the `CGAL::Triangulation_data_structure_3` 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 the Software Design sections of the Chapters Triangulation and Triangulation Datastructure), a cell stores handles to its four vertices and to its four neighbor cells. The vertices and neighbors are indexed 0, 1, 2 and 3. Neighbor `i` lies opposite to vertex `i`.

Since the Triangulation data structure is the class which defines the handle types, the cell base class has to be somehow parameterized by the Triangulation data structure. But since it is itself parameterized by the cell and vertex base classes, there is a cycle in the definition of these classes. In order to break the cycle, the base classes for vertex and cell which are given as arguments for the Triangulation data structure use `void` as Triangulation data structure parameter, and the Triangulation data structure then uses a rebind-like mechanism (similar to the one specified in `std::allocator`) in order to put itself as parameter to the vertex and cell classes. The rebound base classes so obtained are the classes which are used as base classes for the final vertex and cell classes. More information can be found in Section Software Design.

Has models
  `CGAL::Triangulation_ds_cell_base_3<TDS>`

See also
  `TriangulationDSVertexBase_3`
  `CGAL::Triangulation_data_structure_3<Vb,Cb>`

## Types
A model of the concept `TriangulationDSCellBase_3` has to provide the following types.
template<typename TDS3 >
using | Rebind_TDS = unspecified_type
| This template class has to define a type `Rebind_TDS<TDS3>::Other` which is the rebound cell, that is, the one whose `Triangulation_data_structure` will be the actually used one.
typedef TriangulationDataStructure_3 | Triangulation_data_structure
typedef TriangulationDataStructure_3::Vertex_handle | Vertex_handle
typedef TriangulationDataStructure_3::Cell_handle | Cell_handle

## Creation
| TriangulationDSCellBase_3 ()
| Default constructor.
| TriangulationDSCellBase_3 (Vertex_handle v0, Vertex_handle v1, Vertex_handle v2, Vertex_handle v3)
| Initializes the vertices with `v0, v1, v2, v3`.
| TriangulationDSCellBase_3 (Vertex_handle v0, Vertex_handle v1, Vertex_handle v2, Vertex_handle v3, Cell_handle n0, Cell_handle n1, Cell_handle n2, Cell_handle n3)
| Initializes the vertices with `v0, v1, v2, v3` and the neighbors with `n0, n1, n2, n3`.

## Checking
bool | is_valid (bool verbose=false, int level=0) const
| Performs any desired geometric test on a cell.

## Members for Compact_container
Advanced These member functions are required by `CGAL::Triangulation_data_structure_3` because it uses `CGAL::Compact_container` to store its cells. See the documentation of `CGAL::Compact_container` for the exact requirements.
void * | for_compact_container () const
void | for_compact_container (void *p)

## I/O
istream & | operator>> (istream &is, TriangulationDSCellBase_3 &c)
| Inputs the possible non combinatorial information given by the cell.
ostream & | operator<< (ostream &os, const TriangulationDSCellBase_3 &c)
| Outputs the possible non combinatorial information given by the cell.

## Member Typedef Documentation

## ◆ Rebind_TDS

template<typename TDS3 >

using TriangulationDSCellBase_3::Rebind_TDS = unspecified_type

This template class has to define a type `Rebind_TDS<TDS3>::Other` which is the rebound cell, that is, the one whose `Triangulation_data_structure` will be the actually used one.

`Rebind_TDS<TDS3>::Other` will be the real base class of `Triangulation_data_structure_3::Cell`.

Note
  It can be implemented using a nested template class.

See also
  Section Cyclic Dependency

## Constructor & Destructor Documentation

## ◆ TriangulationDSCellBase_3()

TriangulationDSCellBase_3::TriangulationDSCellBase_3 | ( | Vertex_handle | v0,
|  | Vertex_handle | v1,
|  | Vertex_handle | v2,
|  | Vertex_handle | v3
| ) |  |

Initializes the vertices with `v0, v1, v2, v3`.

Neighbors are initialized to the default constructed handle.

## Member Function Documentation

## ◆ is_valid()

bool TriangulationDSCellBase_3::is_valid | ( | bool | verbose = `false`,
|  | int | level = `0`
| ) |  | const

Performs any desired geometric test on a cell.

This is a function for debugging purpose.

Debugging Support

When `verbose` is set to `true`, messages are printed to give a precise indication of the kind of invalidity encountered. `level` increases the level of testing.