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Definition

At the bottom layer, a face stores void * pointers to its three vertices and to its three neighboring faces. The vertices and neighbors are indexed 0,1 and 2 in counterclockwise order around the face. Neighbor i lies opposite to vertex i.

Creation

Face_base f;
default constructor

Face_base f ( void* v0, void* v1, void* v2);
neighbors are initialized to NULL.

Face_base f ( void* v0, void* v1, void* v2, void* n0, void* n1, void* n2);
initializes the vertices with v0,v1, v2 and the neighbors with n0, n1, n2.

Access Functions

int f.dimension () returns the dimension.

void* f.vertex ( int i)
Precondition: 0 i 2.
bool f.has_vertex ( const void* v)
true if v is a vertex of f.
bool f.has_vertex ( const void* v, int& i)
as above and sets i to the index of v
int f.vertex_index ( const void* v)
the index of v in f.
void* f.neighbor ( int i)

Precondition: 0 i 2.
bool f.has_neighbor ( void* n)
true if n is a neighbor of f.
bool f.has_neigbor ( const void* n, int& i)
as above and sets i to the index of n.
int f.face_index ( const void* n)
returns the index of neighbor n.

Setting

void f.set_vertex ( int i, void* v)

Precondition: 0 i 2.
void f.set_vertices () sets the vertices pointers to NULL.
void f.set_vertices ( void* v0, void* v1, void* v2)
sets the vertices pointers.
void f.set_neighbor ( int i, void* n)

Precondition: 0 i 2.
void f.set_neighbors () sets the neighbors pointers to NULL.
void f.set_neighbors ( void* n0, void* n1, void* n2)
sets the neighbors pointers.

void f.reorient () Changes the orientation of fby exchanging vertex(0) with vertex(1) and neighbor(0) with neighbor(1).

void f.ccw_permute () preforms a counterclockwise permutation of the vertices and neighbors of f.

void f.cw_permute () preforms a clockwise permutation of the vertices and neighbors of f.

Checking

bool f.is_valid () To perform any required geometrical test on a face.
Next: Class declaration of Delaunay_triangulation_2<Gt,Tds>
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The GALIA project. Jan 18, 2000.