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/**************************************************************************
* *
* Regina - A Normal Surface Theory Calculator *
* Computational Engine *
* *
* Copyright (c) 1999-2008, 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 */
#include "surfaces/nnormalsurface.h"
#include "triangulation/ntriangulation.h"
#define NO_EDGES std::make_pair(static_cast<NEdge*>(0), static_cast<NEdge*>(0))
namespace regina {
bool NNormalSurfaceVector::isVertexLinking(NTriangulation* triang) const {
unsigned long nTets = triang->getNumberOfTetrahedra();
unsigned long tet;
int type;
for (tet = 0; tet < nTets; tet++) {
for (type = 0; type < 3; type++)
if (getQuadCoord(tet, type, triang) != 0)
return false;
}
if (allowsAlmostNormal())
for (tet = 0; tet < nTets; tet++)
for (type = 0; type < 3; type++)
if (getOctCoord(tet, type, triang) != 0)
return false;
return true;
}
const NVertex* NNormalSurfaceVector::isVertexLink(NTriangulation* triang)
const {
unsigned long nTets = triang->getNumberOfTetrahedra();
unsigned long tet;
int type;
// Check that there are no quad/oct discs.
for (tet = 0; tet < nTets; tet++) {
for (type = 0; type < 3; type++)
if (getQuadCoord(tet, type, triang) != 0)
return 0;
}
if (allowsAlmostNormal())
for (tet = 0; tet < nTets; tet++)
for (type = 0; type < 3; type++)
if (getOctCoord(tet, type, triang) != 0)
return 0;
// Now examine the triangle to see if we link only a single vertex.
stdhash::hash_set<NVertex*, HashPointer> notAns;
/**< We will ignore notAns once ans != 0. */
NVertex* ans = 0;
NLargeInteger ansMult;
NTetrahedron* t;
NVertex* v;
NLargeInteger coord;
for (tet = 0; tet < nTets; tet++) {
t = triang->getTetrahedron(tet);
for (type = 0; type < 4; type++) {
v = t->getVertex(type);
coord = getTriangleCoord(tet, type, triang);
if (coord == 0) {
// No discs in this coordinate.
// Do we have a candidate vertex yet?
if (! ans) {
// Still haven't found a candidate.
notAns.insert(v);
} else if (ans == v) {
// This is our only candidate vertex.
return 0;
}
}
if (coord != 0) {
// Some discs in this coordinate.
// Do we have a candidate vertex?
if (! ans) {
// We've found our first and only possible candidate.
if (notAns.count(v))
return 0;
ans = v;
ansMult = coord;
} else if (ans == v) {
// This vertex matches our current candidate.
if (ansMult != coord)
return 0;
} else {
// This vertex does not match our current candidate.
return 0;
}
} else {
// No discs in this coordinate.
if (ans == v)
return 0;
}
}
}
return ans;
}
std::pair<const NEdge*, const NEdge*> NNormalSurfaceVector::isThinEdgeLink(
NTriangulation* triang) const {
unsigned long nTets = triang->getNumberOfTetrahedra();
unsigned long tet;
int type;
// Check that there are no octagonal discs.
if (allowsAlmostNormal())
for (tet = 0; tet < nTets; tet++)
for (type = 0; type < 3; type++)
if (getOctCoord(tet, type, triang) != 0)
return NO_EDGES;
// Run through the quadrilateral discs and work out if there are any
// valid candidates.
stdhash::hash_set<NEdge*, HashPointer> notAns;
/**< We will ignore notAns once ans != 0. */
bool foundQuads = false;
const NEdge* ans[2];
NLargeInteger ansMultDouble;
NTetrahedron* t;
NEdge* e[6]; // { 2*link, 4*intersect }
NLargeInteger coord;
int i;
for (tet = 0; tet < nTets; tet++) {
t = triang->getTetrahedron(tet);
for (type = 0; type < 3; type++) {
coord = getQuadCoord(tet, type, triang);
e[0] = t->getEdge(edgeNumber[vertexSplitDefn[type][0]]
[vertexSplitDefn[type][1]]);
e[1] = t->getEdge(edgeNumber[vertexSplitDefn[type][2]]
[vertexSplitDefn[type][3]]);
e[2] = t->getEdge(edgeNumber[vertexSplitDefn[type][0]]
[vertexSplitDefn[type][2]]);
e[3] = t->getEdge(edgeNumber[vertexSplitDefn[type][0]]
[vertexSplitDefn[type][3]]);
e[4] = t->getEdge(edgeNumber[vertexSplitDefn[type][1]]
[vertexSplitDefn[type][2]]);
e[5] = t->getEdge(edgeNumber[vertexSplitDefn[type][1]]
[vertexSplitDefn[type][3]]);
if (coord == 0) {
// No discs in this coordinate.
// Do we have any candidate edges yet?
if (foundQuads) {
// Rule out any candidates that should have discs here.
for (i = 0; i < 2; i++)
if (ans[i] == e[0] || ans[i] == e[1])
ans[i] = 0;
} else {
// Still haven't found any candidates.
notAns.insert(e[0]);
notAns.insert(e[1]);
}
} else {
// Some discs in this coordinate.
// Do we have any candidate edges yet?
if (foundQuads) {
// Check consistency with our candidates.
if (e[0] == e[1]) {
// Same edge on both sides of the quad.
// Note that there can only be one candidate now.
if (e[0] == ans[0])
ans[1] = 0;
else if (e[0] == ans[1]) {
ans[0] = ans[1];
ans[1] = 0;
} else
return NO_EDGES;
// The only possible candidate is ans[0].
if (ans[0] == 0 || ansMultDouble != coord)
return NO_EDGES;
} else {
// Different edges on both sides of the quad.
// Check each candidate in turn.
for (i = 0; i < 2; i++)
if (ans[i] != e[0] && ans[i] != e[1])
ans[i] = 0;
if (ansMultDouble != coord * 2)
return NO_EDGES;
}
} else {
// We've found our first and only possible candidates.
if (e[0] == e[1]) {
// Same edge on both sides of the quad.
if (notAns.count(e[0]))
return NO_EDGES;
ans[0] = e[0];
ans[1] = 0;
ansMultDouble = coord;
} else {
// Different edges on both sides of the quad.
for (i = 0; i < 2; i++) {
if (notAns.count(e[i]))
ans[i] = 0;
else {
ans[i] = e[i];
ansMultDouble = coord;
ansMultDouble *= 2;
}
}
}
foundQuads = true;
}
// We now absolutely have candidates (or have exhausted
// them all). Check that these candidates don't
// intersect the new quads.
for (i = 2; i < 6; i++) {
if (ans[0] == e[i])
ans[0] = 0;
if (ans[1] == e[i])
ans[1] = 0;
}
}
// Have we ruled out all the candidates we ever had?
if (foundQuads && (! ans[0]) && (! ans[1]))
return NO_EDGES;
}
}
// So did we actually find anything?
if (! foundQuads)
return NO_EDGES;
if ((! ans[0]) && (! ans[1]))
return NO_EDGES;
// Finally check the triangular discs.
NVertex* v;
bool expectZero[2];
int j;
for (tet = 0; tet < nTets; tet++) {
t = triang->getTetrahedron(tet);
for (type = 0; type < 4; type++) {
v = t->getVertex(type);
coord = getTriangleCoord(tet, type, triang);
// Should we actually see any discs?
for (i = 0; i < 2; i++) {
if (! ans[i])
continue;
// If the candidate edge does not touch this vertex, the
// triangular coordinate should be 0.
expectZero[i] = (v != ans[i]->getVertex(0) &&
v != ans[i]->getVertex(1));
// If this triangular disc type intersects the candidate
// edge, the coordinate should also be 0.
if (! expectZero[i])
for (j = 0; j < 3; j++)
if (t->getEdge(edgeNumber[type][(type + j + 1) % 4])
== ans[i]) {
expectZero[i] = true;
break;
}
// So did we get the right triangular coordinate?
if (expectZero[i]) {
if (coord != 0)
ans[i] = 0;
} else {
if (ansMultDouble != coord * 2)
ans[i] = 0;
}
}
// Have we ruled out all possibilities?
if ((! ans[0]) && (! ans[1]))
return NO_EDGES;
}
}
// Return whatever candidates have survived.
if (ans[0])
return std::make_pair(ans[0], ans[1]);
else
return std::make_pair(ans[1], ans[0]);
}
} // namespace regina
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