CGAL 5.4 - Halfedge Data Structures
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#include <CGAL/HalfedgeDS_items_decorator.h>
Inherited by CGAL::HalfedgeDS_const_decorator< HDS >, and CGAL::HalfedgeDS_decorator< HDS > [private]
.
The class CGAL::HalfedgeDS_items_decorator<HDS>
provides additional functions for vertices, halfedges, and faces of a halfedge data structure without knowing the containing halfedge data structure.
The class CGAL::HalfedgeDS_decorator<HDS>
stores a reference to the halfedge data structure and provides functions that modify the halfedge data structure, for example Euler-operators. The class CGAL::HalfedgeDS_const_decorator<HDS>
stores a const reference to the halfedge data structure. It contains non-modifying functions, for example the test for validness of the data structure.
All these additional functions take care of the different capabilities a halfedge data structure may have or may not have. The functions evaluate the type tags of the halfedge data structure to decide on the actions. If a particular feature is not supported nothing is done. Note that for example the creation of new halfedges is mandatory for all halfedge data structures and will not appear here again.
CGAL::HalfedgeDS_decorator<HDS>
CGAL::HalfedgeDS_const_decorator<HDS>
Example
The following program fragment illustrates how a refined halfedge class for a polyhedron can make use of the find_prev()
member function to implement a prev()
member function that works regardless of whether the halfedge data structure HDS
provides a prev()
member function for its halfedges or not. In the case that not, the implementation given here runs in time proportional to the size of the incident face. For const-correctness a second implementation with signature Halfedge_const_handle prev() const;
is needed.
Note also the use of the static member function HalfedgeDS::halfedge_handle()
of the halfedge data structure. It converts a pointer to the halfedge into a halfedge handle. This conversion encapsulates possible adjustments for hidden data members in the true halfedge type, such as linked-list pointers.
Types | |
The respective | |
typedef unspecified_type | HalfedgeDS |
halfedge data structure. | |
typedef unspecified_type | Vertex |
vertex type of HalfedgeDS . | |
typedef unspecified_type | Halfedge |
halfedge type of HalfedgeDS . | |
typedef unspecified_type | Face |
face type of HalfedgeDS . | |
typedef unspecified_type | Vertex_handle |
typedef unspecified_type | Halfedge_handle |
typedef unspecified_type | Face_handle |
typedef unspecified_type | Vertex_iterator |
typedef unspecified_type | Halfedge_iterator |
typedef unspecified_type | Face_iterator |
typedef unspecified_type | size_type |
typedef unspecified_type | difference_type |
typedef unspecified_type | iterator_category |
typedef unspecified_type | Supports_vertex_halfedge |
typedef unspecified_type | Supports_halfedge_prev |
typedef unspecified_type | Supports_halfedge_vertex |
typedef unspecified_type | Supports_halfedge_face |
typedef unspecified_type | Supports_face_halfedge |
typedef unspecified_type | Supports_removal |
Creation | |
HalfedgeDS_items_decorator () | |
default constructor. | |
Access Functions | |
Corresponding member functions for | |
Halfedge_handle | get_vertex_halfedge (Vertex_handle v) |
returns the incident halfedge of v if supported, Halfedge_handle() otherwise. | |
Vertex_handle | get_vertex (Halfedge_handle h) |
returns the incident vertex of h if supported, Vertex_handle() otherwise. | |
Halfedge_handle | get_prev (Halfedge_handle h) |
returns the previous halfedge of h if supported, Halfedge_handle() otherwise. | |
Halfedge_handle | find_prev (Halfedge_handle h) |
returns the previous halfedge of h . More... | |
Halfedge_handle | find_prev_around_vertex (Halfedge_handle h) |
returns the previous halfedge of h . More... | |
Face_handle | get_face (Halfedge_handle h) |
returns the incident face of h if supported, Face_handle() otherwise. | |
Halfedge_handle | get_face_halfedge (Face_handle f) |
returns the incident halfedge of f if supported, Halfedge_handle() otherwise. | |
Modifying Functions (Composed) | |
void | close_tip (Halfedge_handle h) const |
makes h->opposite() the successor of h . | |
void | close_tip (Halfedge_handle h, Vertex_handle v) const |
makes h->opposite() the successor of h and sets the incident vertex of h to v . | |
void | insert_tip (Halfedge_handle h, Halfedge_handle v) const |
inserts the tip of the edge h into the halfedges around the vertex pointed to by v . More... | |
void | remove_tip (Halfedge_handle h) const |
removes the edge h->next()->opposite() from the halfedge circle around the vertex referred to by h . More... | |
void | insert_halfedge (Halfedge_handle h, Halfedge_handle f) const |
inserts the halfedge h between f and f->next() . More... | |
void | remove_halfedge (Halfedge_handle h) const |
removes edge h->next() from the halfedge circle around the face referred to by h . More... | |
void | set_vertex_in_vertex_loop (Halfedge_handle h, Vertex_handle v) const |
loops around the vertex incident to h and sets all vertex pointers to v . More... | |
void | set_face_in_face_loop (Halfedge_handle h, Face_handle f) const |
loops around the face incident to h and sets all face pointers to f . More... | |
Halfedge_handle | flip_edge (Halfedge_handle h) const |
performs an edge flip. More... | |
Modifying Functions (Primitives) | |
void | set_vertex_halfedge (Vertex_handle v, Halfedge_handle g) const |
sets the incident halfedge of v to g . | |
void | set_vertex_halfedge (Halfedge_handle h) const |
sets the incident halfedge of the vertex v to h . | |
void | set_vertex (Halfedge_handle h, Vertex_handle v) const |
sets the incident vertex of h to v . | |
void | set_prev (Halfedge_handle h, Halfedge_handle g) const |
sets the previous link of h to g . | |
void | set_face (Halfedge_handle h, Face_handle f) const |
sets the incident face of h to f . | |
void | set_face_halfedge (Face_handle f, Halfedge_handle g) const |
sets the incident halfedge of f to g . | |
void | set_face_halfedge (Halfedge_handle h) const |
sets the incident halfedge of the face f to h . | |
Halfedge_handle CGAL::HalfedgeDS_items_decorator< HDS >::find_prev | ( | Halfedge_handle | h | ) |
returns the previous halfedge of h
.
Uses the prev()
method if supported or performs a search around the face using next()
.
Halfedge_handle CGAL::HalfedgeDS_items_decorator< HDS >::find_prev_around_vertex | ( | Halfedge_handle | h | ) |
returns the previous halfedge of h
.
Uses the prev()
method if supported or performs a search around the vertex using next()
.
Halfedge_handle CGAL::HalfedgeDS_items_decorator< HDS >::flip_edge | ( | Halfedge_handle | h | ) | const |
performs an edge flip.
It returns h
after rotating the edge h
one vertex in the direction of the face orientation.
h != Halfedge_handle()
and both incident faces of h
are triangles. void CGAL::HalfedgeDS_items_decorator< HDS >::insert_halfedge | ( | Halfedge_handle | h, |
Halfedge_handle | f | ||
) | const |
inserts the halfedge h
between f
and f->next()
.
The face of h
will be the one f
refers to if faces are supported.
void CGAL::HalfedgeDS_items_decorator< HDS >::insert_tip | ( | Halfedge_handle | h, |
Halfedge_handle | v | ||
) | const |
inserts the tip of the edge h
into the halfedges around the vertex pointed to by v
.
Halfedge h->opposite()
is the new successor of v
and h->next()
will be set to v->next()
. The vertex of h
will be set to the vertex v
refers to if vertices are supported.
void CGAL::HalfedgeDS_items_decorator< HDS >::remove_halfedge | ( | Halfedge_handle | h | ) | const |
removes edge h->next()
from the halfedge circle around the face referred to by h
.
The new successor of h
will be h->next()->next()
.
void CGAL::HalfedgeDS_items_decorator< HDS >::remove_tip | ( | Halfedge_handle | h | ) | const |
removes the edge h->next()->opposite()
from the halfedge circle around the vertex referred to by h
.
The new successor halfedge of h
will be h->next()->opposite()->next()
.
void CGAL::HalfedgeDS_items_decorator< HDS >::set_face_in_face_loop | ( | Halfedge_handle | h, |
Face_handle | f | ||
) | const |
loops around the face incident to h
and sets all face pointers to f
.
h != Halfedge_handle()
. void CGAL::HalfedgeDS_items_decorator< HDS >::set_vertex_in_vertex_loop | ( | Halfedge_handle | h, |
Vertex_handle | v | ||
) | const |
loops around the vertex incident to h
and sets all vertex pointers to v
.
h != Halfedge_handle()
.