CGAL 6.1 - 3D Triangulation Data Structure

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TriangulationDataStructure_3::Cell Concept Reference
Reference Manual » Concepts

## Definition

The concept `TriangulationDataStructure_3::Cell` stores four `Vertex_handle`s to its four vertices and four `Cell_handle`s to its four neighbors. The vertices are indexed 0, 1, 2, and 3 in consistent order. The neighbor indexed \( i\) lies opposite to vertex `i`.

In degenerate dimensions, cells are used to store faces of maximal dimension: in dimension 2, each cell represents only one facet of index 3, and 3 edges \( (0,1)\), \( (1,2)\) and \( (2,0)\); in dimension 1, each cell represents one edge \( (0,1)\). (See also Section Representation.)

Creation

In order to obtain new cells or destruct unused cells, the user must call the `create_cell()` and `delete_cell()` methods of the triangulation data structure.

See also
  `TriangulationDataStructure_3::Vertex`
  `TriangulationDataStructure_3::Cell_data`

## Types
typedef TriangulationDataStructure_3 | Triangulation_data_structure
typedef TriangulationDataStructure_3::Vertex_handle | Vertex_handle
typedef TriangulationDataStructure_3::Cell_handle | Cell_handle
typedef TriangulationDataStructure_3::Cell_data | TDS_data

## Access Functions
Vertex_handle | vertex (int i) const
| Returns the vertex `i` of `c`.
int | index (Vertex_handle v) const
| Returns the index of vertex `v` in `c`.
bool | has_vertex (Vertex_handle v) const
| Returns `true` if `v` is a vertex of `c`.
bool | has_vertex (Vertex_handle v, int &i) const
| Returns `true` if `v` is a vertex of `c`, and computes its index `i` in `c`.
Cell_handle | neighbor (int i) const
| Returns the neighbor `i` of `c`.
int | index (Cell_handle n) const
| Returns the index corresponding to neighboring cell `n`.
bool | has_neighbor (Cell_handle n) const
| Returns `true` if `n` is a neighbor of `c`.
bool | has_neighbor (Cell_handle n, int &i) const
| Returns `true` if `n` is a neighbor of `c`, and computes its index `i` in `c`.

## Setting
void | set_vertex (int i, Vertex_handle v)
| Sets vertex `i` to `v`.
void | set_vertices (Vertex_handle v0, Vertex_handle v1, Vertex_handle v2, Vertex_handle v3)
| Sets the vertex pointers.
void | set_neighbor (int i, Cell_handle n)
| Sets neighbor `i` to `n`.
void | set_neighbors (Cell_handle n0, Cell_handle n1, Cell_handle n2, Cell_handle n3)
| Sets the neighbors pointers.

## Internal
Advanced These functions are used internally by the triangulation data structure. The user is not encouraged to use them directly as they may change in the future.
TDS_data & | tds_data ()
const TDS_data & | tds_data () const

## Checking
bool | is_valid (bool verbose=false, int level=0) const
| This is a function for debugging purpose.

## Member Function Documentation

## ◆ index() [1/2]

int TriangulationDataStructure_3::Cell::index | ( | Cell_handle | n | ) | const

Returns the index corresponding to neighboring cell `n`.

Precondition
  `n` is a neighbor of `c`.

## ◆ index() [2/2]

int TriangulationDataStructure_3::Cell::index | ( | Vertex_handle | v | ) | const

Returns the index of vertex `v` in `c`.

Precondition
  `v` is a vertex of `c`.

## ◆ is_valid()

bool TriangulationDataStructure_3::Cell::is_valid | ( | bool | verbose = `false`,
|  | int | level = `0`
| ) |  | const

This is a function for debugging purpose.

Debugging Support

User defined local validity checking function.

## ◆ neighbor()

Cell_handle TriangulationDataStructure_3::Cell::neighbor | ( | int | i | ) | const

Returns the neighbor `i` of `c`.

Precondition
  \( i \in\{0, 1, 2, 3\}\).

## ◆ set_neighbor()

void TriangulationDataStructure_3::Cell::set_neighbor | ( | int | i,
|  | Cell_handle | n
| ) |  |

Sets neighbor `i` to `n`.

Precondition
  \( i \in\{0, 1, 2, 3\}\).

## ◆ set_vertex()

void TriangulationDataStructure_3::Cell::set_vertex | ( | int | i,
|  | Vertex_handle | v
| ) |  |

Sets vertex `i` to `v`.

Precondition
  \( i \in\{0, 1, 2, 3\}\).

## ◆ vertex()

Vertex_handle TriangulationDataStructure_3::Cell::vertex | ( | int | i | ) | const

Returns the vertex `i` of `c`.

Precondition
  \( i \in\{0, 1, 2, 3\}\).