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/**************************************************************************
* *
* Regina - A Normal Surface Theory Calculator *
* Computational Engine *
* *
* Copyright (c) 1999-2025, 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. *
* *
* As an exception, when this program is distributed through (i) the *
* App Store by Apple Inc.; (ii) the Mac App Store by Apple Inc.; or *
* (iii) Google Play by Google Inc., then that store may impose any *
* digital rights management, device limits and/or redistribution *
* restrictions that are required by its terms of service. *
* *
* 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, see <https://www.gnu.org/licenses/>. *
* *
**************************************************************************/
#include "surface/normalsurface.h"
#include "surface/disc.h"
namespace regina {
bool numberDiscsAwayFromVertex(int discType, int vertex) {
if (discType < 4)
return (vertex == discType);
return (vertex == 0 || vertex == quadPartner[(discType - 1) % 3][0]);
}
bool discOrientationFollowsEdge(int discType, int vertex, int edgeStart,
int edgeEnd) {
Perm<4> forwards(vertex, edgeStart, edgeEnd, 6-vertex-edgeStart-edgeEnd);
Perm<4> reverse(vertex, edgeEnd, edgeStart, 6-vertex-edgeStart-edgeEnd);
if (discType < 4) {
for (int i = 0; i < 3; i++) {
if (triDiscArcs[discType][i] == forwards)
return true;
if (triDiscArcs[discType][i] == reverse)
return false;
}
}
else if (discType < 7) {
for (int i = 0; i < 4; i++) {
if (quadDiscArcs[discType - 4][i] == forwards)
return true;
if (quadDiscArcs[discType - 4][i] == reverse)
return false;
}
}
else {
for (int i = 0; i < 8; i++) {
if (octDiscArcs[discType - 7][i] == forwards)
return true;
if (octDiscArcs[discType - 7][i] == reverse)
return false;
}
}
return false;
}
DiscSetTet::DiscSetTet(const NormalSurface& surface, size_t tetIndex) {
int i;
for (i=0; i<4; i++)
discs_[i] = surface.triangles(tetIndex, i).longValue();
for (i=4; i<7; i++)
discs_[i] = surface.quads(tetIndex, i - 4).longValue();
for (i=7; i<10; i++)
discs_[i] = surface.octs(tetIndex, i - 7).longValue();
}
unsigned long DiscSetTet::arcFromDisc(int /* arcFace */, int arcVertex,
int discType, unsigned long discNumber) const {
// Is it a triangle?
if (discType < 4)
return discNumber;
// It's a quad or an octagon.
// Note that there is at most one octagonal or quad type present
// (since the surface must be embedded), so this must be it.
if (arcVertex == 0 || arcVertex == quadPartner[(discType - 1) % 3][0])
return discs_[arcVertex] + discNumber;
else
return discs_[arcVertex] + discs_[discType]
- discNumber - 1;
}
std::pair<int, unsigned long> DiscSetTet::discFromArc(int arcFace, int arcVertex,
unsigned long arcNumber) const {
// Is it a triangle?
if (arcNumber < discs_[arcVertex])
return { arcVertex, arcNumber };
// It's a quad or an octagon.
// Note that there is at most one octagonal or quad type present
// (since the surface must be embedded), so this must be it.
int discType;
if (discs_[quadSeparating[arcVertex][arcFace] + 4] > 0)
discType = quadSeparating[arcVertex][arcFace] + 4;
else if (discs_[quadMeeting[arcVertex][arcFace][0] + 7] > 0)
discType = quadMeeting[arcVertex][arcFace][0] + 7;
else
discType = quadMeeting[arcVertex][arcFace][1] + 7;
unsigned long discNumber;
if (arcVertex == 0 || arcVertex == quadPartner[(discType - 1) % 3][0])
discNumber = arcNumber - discs_[arcVertex];
else
discNumber = discs_[discType] - (arcNumber - discs_[arcVertex]) - 1;
return { discType, discNumber };
}
} // namespace regina
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