Regina Calculation Engine
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Represents a component of the boundary of a triangulation. More...
#include <triangulation/nboundarycomponent.h>
Public Member Functions | |
virtual | ~NBoundaryComponent () |
Default destructor. | |
unsigned long | getNumberOfFaces () const |
Returns the number of faces in this boundary component. | |
unsigned long | getNumberOfEdges () const |
Returns the number of edges in this boundary component. | |
unsigned long | getNumberOfVertices () const |
Returns the number of vertices in this boundary component. | |
NFace * | getFace (unsigned long index) const |
Returns the requested face in this boundary component. | |
NEdge * | getEdge (unsigned long index) const |
Returns the requested edge in this boundary component. | |
NVertex * | getVertex (unsigned long index) const |
Returns the requested vertex in this boundary component. | |
long | getEulerCharacteristic () const |
Returns the Euler characteristic of this boundary component. | |
bool | isIdeal () const |
Determines if this boundary component is ideal. | |
bool | isOrientable () const |
Determines if this boundary component is orientable. | |
void | writeTextShort (std::ostream &out) const |
Writes this object in short text format to the given output stream. | |
Friends | |
class | NTriangulation |
Allow access to private members. |
Represents a component of the boundary of a triangulation.
Note that an ideal vertex constitutes a boundary component of its own.
We can run into some interesting cases with invalid triangulations. Suppose some vertex link is a multiply punctured surface (which makes the vertex and hence the entire triangulation invalid). This means that different parts of the 3-manifold boundary are effectively "pinched" together. If this happens, the different parts of the boundary that are pinched might or might not be listed as part of the same boundary component; if not then the offending vertex will be included in all of these boundary components. Nevertheless, only one of these can be considered the "official" boundary component of the vertex as returned by NVertex::getBoundaryComponent(). This is all a bit of a mess, but then again the entire triangulation is invalid and so you almost certainly have bigger problems to deal with.
Boundary components are highly temporary; once a triangulation changes, all its boundary component objects will be deleted and new ones will be created.
regina::NBoundaryComponent::~NBoundaryComponent | ( | ) | [inline, virtual] |
Default destructor.
NEdge * regina::NBoundaryComponent::getEdge | ( | unsigned long | index | ) | const [inline] |
Returns the requested edge in this boundary component.
For an ideal boundary component (which consists of a single vertex), there are no real edges in the boundary component and this routine cannot be used.
index | the index of the requested edge in the boundary component. This should be between 0 and getNumberOfEdges()-1 inclusive. Note that the index of a edge in the boundary component need not be the index of the same edge in the entire triangulation. |
long regina::NBoundaryComponent::getEulerCharacteristic | ( | ) | const [inline] |
Returns the Euler characteristic of this boundary component.
If this boundary component is ideal, the Euler characteristic of the link of the corresponding ideal vertex is returned.
NFace * regina::NBoundaryComponent::getFace | ( | unsigned long | index | ) | const [inline] |
Returns the requested face in this boundary component.
For an ideal boundary component (which consists of a single vertex), there are no real faces in the boundary component and this routine cannot be used.
index | the index of the requested face in the boundary component. This should be between 0 and getNumberOfFaces()-1 inclusive. Note that the index of a face in the boundary component need not be the index of the same face in the entire triangulation. |
unsigned long regina::NBoundaryComponent::getNumberOfEdges | ( | ) | const [inline] |
Returns the number of edges in this boundary component.
unsigned long regina::NBoundaryComponent::getNumberOfFaces | ( | ) | const [inline] |
Returns the number of faces in this boundary component.
unsigned long regina::NBoundaryComponent::getNumberOfVertices | ( | ) | const [inline] |
Returns the number of vertices in this boundary component.
NVertex * regina::NBoundaryComponent::getVertex | ( | unsigned long | index | ) | const [inline] |
Returns the requested vertex in this boundary component.
index | the index of the requested vertex in the boundary component. This should be between 0 and getNumberOfVertices()-1 inclusive. Note that the index of a vertex in the boundary component need not be the index of the same vertex in the entire triangulation. |
bool regina::NBoundaryComponent::isIdeal | ( | ) | const [inline] |
Determines if this boundary component is ideal.
This is the case if and only if it consists of a single (ideal) vertex and no faces.
true
if and only if this boundary component is ideal. bool regina::NBoundaryComponent::isOrientable | ( | ) | const [inline] |
Determines if this boundary component is orientable.
If the boundary component is ideal, the orientability of the link of the corresponding ideal vertex is returned.
true
if and only if this boundary component is orientable. void regina::NBoundaryComponent::writeTextShort | ( | std::ostream & | out | ) | const [inline, virtual] |
Writes this object in short text format to the given output stream.
The output should fit on a single line and no newline should be written.
out | the output stream to which to write. |
Implements regina::ShareableObject.
friend class NTriangulation [friend] |
Allow access to private members.