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/**************************************************************************
* *
* Regina - A Normal Surface Theory Calculator *
* Computational Engine *
* *
* Copyright (c) 1999-2011, Ben Burton *
* For further details contact Ben Burton (bab@debian.org). *
* *
* This program is free software; you can redistribute it and/or *
* modify it under the terms of the GNU General Public License as *
* published by the Free Software Foundation; either version 2 of the *
* License, or (at your option) any later version. *
* *
* This program is distributed in the hope that it will be useful, but *
* WITHOUT ANY WARRANTY; without even the implied warranty of *
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU *
* General Public License for more details. *
* *
* You should have received a copy of the GNU General Public *
* License along with this program; if not, write to the Free *
* Software Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, *
* MA 02110-1301, USA. *
* *
**************************************************************************/
/* end stub */
/*! \file subcomplex/nsnappedball.h
* \brief Deals with snapped 3-balls in a triangulation.
*/
#ifndef __NSNAPPEDBALL_H
#ifndef __DOXYGEN
#define __NSNAPPEDBALL_H
#endif
#include "regina-core.h"
#include "subcomplex/nstandardtri.h"
#include "triangulation/nedge.h"
namespace regina {
class NTetrahedron;
/**
* \weakgroup subcomplex
* @{
*/
/**
* Represents a snapped 3-ball in a triangulation.
* A snapped 3-ball is a single tetrahedron with two faces glued to each
* other to form a 3-ball with a two triangle boundary.
*
* All optional NStandardTriangulation routines are implemented for this
* class.
*/
class REGINA_API NSnappedBall : public NStandardTriangulation {
private:
NTetrahedron* tet;
/**< The tetrahedron that forms the snapped ball. */
int equator;
/**< The edge that forms the equator on the ball boundary. */
public:
/**
* Returns a newly created clone of this structure.
*
* @return a newly created clone.
*/
NSnappedBall* clone() const;
/**
* Returns the tetrahedron that forms this snapped ball.
*
* @return the tetrahedron.
*/
NTetrahedron* getTetrahedron() const;
/**
* Returns one of the two faces that forms the boundary of this
* snapped ball.
*
* You are guaranteed that index 0 will return a smaller face
* number than index 1.
*
* @param index specifies which of the two boundary faces to return;
* this must be either 0 or 1.
* @return the corresponding face number in the tetrahedron.
*/
int getBoundaryFace(int index) const;
/**
* Returns one of the two faces internal to this snapped ball.
*
* You are guaranteed that index 0 will return a smaller face
* number than index 1.
*
* @param index specifies which of the two internal faces to return;
* this must be either 0 or 1.
* @return the corresponding face number in the tetrahedron.
*/
int getInternalFace(int index) const;
/**
* Returns the edge that forms the equator of the boundary sphere
* of this ball.
*
* @return the corresponding edge number in the tetrahedron.
*/
int getEquatorEdge() const;
/**
* Returns the edge internal to this snapped ball.
*
* @return the corresponding edge number in the tetrahedron.
*/
int getInternalEdge() const;
/**
* Determines if the given tetrahedron forms a snapped 3-ball
* within a triangulation. The ball need not be the entire
* triangulation; the boundary faces may be glued to something
* else (or to each other).
*
* Note that the two boundary faces of the snapped 3-ball
* need not be boundary faces within the overall
* triangulation, i.e., they may be identified with each other
* or with faces of other tetrahedra.
*
* @param tet the tetrahedron to examine as a potential 3-ball.
* @return a newly created structure containing details of the
* snapped 3-ball, or \c null if the given tetrahedron is
* not a snapped 3-ball.
*/
static NSnappedBall* formsSnappedBall(NTetrahedron* tet);
NManifold* getManifold() const;
NAbelianGroup* getHomologyH1() const;
std::ostream& writeName(std::ostream& out) const;
std::ostream& writeTeXName(std::ostream& out) const;
void writeTextLong(std::ostream& out) const;
private:
/**
* Creates a new uninitialised structure.
*/
NSnappedBall();
};
/*@}*/
// Inline functions for NSnappedBall
inline NSnappedBall::NSnappedBall() {
}
inline NTetrahedron* NSnappedBall::getTetrahedron() const {
return tet;
}
inline int NSnappedBall::getBoundaryFace(int index) const {
return index == 0 ?
NEdge::edgeVertex[5 - equator][0] :
NEdge::edgeVertex[5 - equator][1];
}
inline int NSnappedBall::getInternalFace(int index) const {
return index == 0 ?
NEdge::edgeVertex[equator][0] :
NEdge::edgeVertex[equator][1];
}
inline int NSnappedBall::getEquatorEdge() const {
return equator;
}
inline int NSnappedBall::getInternalEdge() const {
return 5 - equator;
}
inline std::ostream& NSnappedBall::writeName(std::ostream& out) const {
return out << "Snap";
}
inline std::ostream& NSnappedBall::writeTeXName(std::ostream& out) const {
return out << "\\mathit{Snap}";
}
inline void NSnappedBall::writeTextLong(std::ostream& out) const {
out << "Snapped 3-ball";
}
} // namespace regina
#endif
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