void data_to_triangulation(
TriangulationData *data,
Triangulation **manifold_ptr)
{
/*
* We assume the UI has done some basic error checking
* on the data, so we don't repeat it here.
*/
Triangulation *manifold;
Tetrahedron **tet_array;
Cusp **cusp_array;
Boolean cusps_are_given;
int i,
j,
k,
l,
m;
Boolean all_peripheral_curves_are_zero,
finite_vertices_are_present;
/*
* Initialize *manifold_ptr to NULL.
* We'll do all our work with manifold, and then copy
* manifold to *manifold_ptr at the very end.
*/
*manifold_ptr = NULL;
/*
* Allocate and initialize the Triangulation structure.
*/
manifold = NEW_STRUCT(Triangulation);
initialize_triangulation(manifold);
/*
* Allocate and copy the name.
*/
manifold->name = NEW_ARRAY(strlen(data->name) + 1, char);
strcpy(manifold->name, data->name);
/*
* Set up the global information.
*
* The hyperbolic structure is included in the file only for
* human readers; here we recompute it from scratch.
*/
manifold->num_tetrahedra = data->num_tetrahedra;
manifold->solution_type[complete] = not_attempted;
manifold->solution_type[ filled ] = not_attempted;
manifold->orientability = data->orientability;
manifold->num_or_cusps = data->num_or_cusps;
manifold->num_nonor_cusps = data->num_nonor_cusps;
manifold->num_cusps = manifold->num_or_cusps
+ manifold->num_nonor_cusps;
/*
* Allocate the Tetrahedra.
* Keep pointers to them on a temporary array, so we can
* find them by their indices.
*/
tet_array = NEW_ARRAY(manifold->num_tetrahedra, Tetrahedron *);
for (i = 0; i < manifold->num_tetrahedra; i++)
{
tet_array[i] = NEW_STRUCT(Tetrahedron);
initialize_tetrahedron(tet_array[i]);
INSERT_BEFORE(tet_array[i], &manifold->tet_list_end);
}
/*
* If num_or_cusps or num_nonor_cusps is nonzero, allocate the Cusps.
* Keep pointers to them on temporary arrays, so we can find them
* by their indices.
* Otherwise we will create arbitrary Cusps later.
*/
cusps_are_given = (data->num_or_cusps != 0) || (data->num_nonor_cusps != 0);
if (cusps_are_given == TRUE)
{
cusp_array = NEW_ARRAY(manifold->num_cusps, Cusp *);
for (i = 0; i < manifold->num_cusps; i++)
{
cusp_array[i] = NEW_STRUCT(Cusp);
initialize_cusp(cusp_array[i]);
INSERT_BEFORE(cusp_array[i], &manifold->cusp_list_end);
}
}
/* DJH */
void my_drill_tube(
Triangulation *manifold,
int singular_index )
{
/*
* Insert a triangular-pillow-with-tunnel (as described at the top
* of this file) so as to connect the boundary component at one
* end of the given edge to the boundary component at the other end.
* The orientation on the triangular pillow will match the
* orientation on tet, so that the orientation on the manifold
* (if there is one) will be preserved. Edge orientations are also
* respected.
*/
EdgeIndex e;
VertexIndex v0,
v1,
v2,
vv0,
vv1,
vv2;
FaceIndex f,
ff;
Tetrahedron *nbr_tet, *tet, *tet0,
*new_tet0,
*new_tet1;
Permutation gluing;
EdgeClass *edge0,
*edge1,
*edge2, *edge,
*new_edge,
*edge3;
Orientation edge_orientation0,
edge_orientation1,
edge_orientation2;
PeripheralCurve c;
Orientation h;
int num_strands,
i,
intersection_number[2],
the_gcd;
Cusp *unique_cusp, *merged_cusp, *dead_cusp, *cusp;
MatrixInt22 *basis_change = NULL;
Boolean creating_new_cusp, same_cusp;
int *cone_points, num_cone_points, dead_index;
for( edge = manifold->edge_list_begin.next;
edge!=&manifold->edge_list_end;
edge = edge->next )
if (edge->is_singular)
if (edge->singular_index == singular_index)
break;
if (edge == &manifold->edge_list_end)
uFatalError("my_drill_tube", "finite_vertices");
tet = edge->incident_tet;
e = edge->incident_edge_index;
/*
* Relative to the orientation of tet, the vertices v0, v1 and v2
* are arranged in counterclockwise order around the face f.
*/
v0 = one_vertex_at_edge[e];
v1 = other_vertex_at_edge[e];
if ( tet->cusp[v0] == tet->cusp[v1]
&& tet->cusp[v1]->num_cone_points ==2 /* if it's a $\S^2(n,n) orbifold then we are creating a torus cusp */
&& tet->cusp[v1]->euler_characteristic==2)
creating_new_cusp = TRUE;
else creating_new_cusp = FALSE;
v2 = remaining_face[v1][v0];
f = remaining_face[v0][v1];
/*
* Note the matching face and its vertices.
*/
nbr_tet = tet->neighbor[f];
gluing = tet->gluing[f];
ff = EVALUATE(gluing, f);
vv0 = EVALUATE(gluing, v0);
vv1 = EVALUATE(gluing, v1);
vv2 = EVALUATE(gluing, v2);
/*
* Note the incident EdgeClasses (which may or may not be distinct).
*/
edge0 = tet->edge_class[e];
edge1 = tet->edge_class[edge_between_vertices[v1][v2]];
edge2 = tet->edge_class[edge_between_vertices[v2][v0]];
/*
* Construct the triangular-pillow-with-tunnel, as described
* at the top of this file.
*/
new_tet0 = NEW_STRUCT(Tetrahedron);
new_tet1 = NEW_STRUCT(Tetrahedron);
initialize_tetrahedron(new_tet0);
initialize_tetrahedron(new_tet1);
INSERT_BEFORE(new_tet0, &manifold->tet_list_end);
INSERT_BEFORE(new_tet1, &manifold->tet_list_end);
manifold->num_tetrahedra += 2;
new_edge = NEW_STRUCT(EdgeClass);
initialize_edge_class(new_edge);
INSERT_BEFORE(new_edge, &manifold->edge_list_end);
new_tet0->neighbor[0] = new_tet1;
new_tet0->neighbor[1] = NULL; /* assigned below */
new_tet0->neighbor[2] = NULL; /* assigned below */
new_tet0->neighbor[3] = new_tet1;
new_tet1->neighbor[0] = new_tet0;
new_tet1->neighbor[1] = new_tet1;
new_tet1->neighbor[2] = new_tet1;
new_tet1->neighbor[3] = new_tet0;
new_tet0->gluing[0] = CREATE_PERMUTATION(0, 0, 1, 2, 2, 1, 3, 3);
new_tet0->gluing[1] = 0x00; /* assigned below */
new_tet0->gluing[2] = 0x00; /* assigned below */
new_tet0->gluing[3] = CREATE_PERMUTATION(0, 1, 1, 0, 2, 2, 3, 3);
new_tet1->gluing[0] = CREATE_PERMUTATION(0, 0, 1, 2, 2, 1, 3, 3);
new_tet1->gluing[1] = CREATE_PERMUTATION(0, 0, 1, 2, 2, 1, 3, 3);
new_tet1->gluing[2] = CREATE_PERMUTATION(0, 0, 1, 2, 2, 1, 3, 3);
new_tet1->gluing[3] = CREATE_PERMUTATION(0, 1, 1, 0, 2, 2, 3, 3);
new_tet0->edge_class[0] = edge1;
new_tet0->edge_class[1] = edge1;
new_tet0->edge_class[2] = edge0;
new_tet0->edge_class[3] = edge2;
new_tet0->edge_class[4] = edge0;
new_tet0->edge_class[5] = edge0;
new_tet1->edge_class[0] = edge1;
new_tet1->edge_class[1] = edge1;
new_tet1->edge_class[2] = edge0;
new_tet1->edge_class[3] = new_edge;
new_tet1->edge_class[4] = edge0;
new_tet1->edge_class[5] = edge0;
edge0->order += 6;
edge1->order += 4;
edge2->order += 1;
new_edge->order = 1;
new_edge->incident_tet = new_tet1;
new_edge->incident_edge_index = 3;
edge_orientation0 = tet->edge_orientation[e];
edge_orientation1 = tet->edge_orientation[edge_between_vertices[v1][v2]];
edge_orientation2 = tet->edge_orientation[edge_between_vertices[v2][v0]];
new_tet0->edge_orientation[0] = edge_orientation1;
new_tet0->edge_orientation[1] = edge_orientation1;
new_tet0->edge_orientation[2] = edge_orientation0;
new_tet0->edge_orientation[3] = edge_orientation2;
new_tet0->edge_orientation[4] = edge_orientation0;
new_tet0->edge_orientation[5] = edge_orientation0;
new_tet1->edge_orientation[0] = edge_orientation1;
new_tet1->edge_orientation[1] = edge_orientation1;
new_tet1->edge_orientation[2] = edge_orientation0;
new_tet1->edge_orientation[3] = right_handed;
new_tet1->edge_orientation[4] = edge_orientation0;
new_tet1->edge_orientation[5] = edge_orientation0;
new_tet0->cusp[0] = tet->cusp[v0];
new_tet0->cusp[1] = tet->cusp[v0];
new_tet0->cusp[2] = tet->cusp[v0];
new_tet0->cusp[3] = tet->cusp[v2];
new_tet1->cusp[0] = tet->cusp[v0];
new_tet1->cusp[1] = tet->cusp[v0];
new_tet1->cusp[2] = tet->cusp[v0];
new_tet1->cusp[3] = tet->cusp[v2];
/*
* Install the triangular-pillow-with-tunnel.
*/
tet->neighbor[f] = new_tet0;
tet->gluing[f] = CREATE_PERMUTATION(f, 2, v0, 0, v1, 1, v2, 3);
new_tet0->neighbor[2] = tet;
new_tet0->gluing[2] = inverse_permutation[tet->gluing[f]];
nbr_tet->neighbor[ff] = new_tet0;
nbr_tet->gluing[ff] = CREATE_PERMUTATION(ff, 1, vv0, 0, vv1, 2, vv2, 3);
new_tet0->neighbor[1] = nbr_tet;
new_tet0->gluing[1] = inverse_permutation[nbr_tet->gluing[ff]];
for(c=0;c<2;c++)
for(h=0;h<2;h++)
{
new_tet0->curve[c][h][3][2] = -nbr_tet->curve[c][h][v2][f];
new_tet0->curve[c][h][3][1] = -nbr_tet->curve[c][h][vv2][ff];
}
/*
* Typically creating_new_cusp is FALSE, meaning that we are
* connecting a spherical boundary component to a torus or
* Klein bottle boundary component, and we simply extend the
* existing peripheral curves across the new tetrahedra.
*
* In the exceptional case that creating_new_cusp is TRUE,
* meaning that the manifold has no real cusps and we are
* connecting the "special fake cusp" to itself, we must
* install a meridian and longitude, and set up the Dehn filling.
*/
if (creating_new_cusp == FALSE)
{
if (tet->cusp[v0]->index<tet->cusp[v1]->index)
{
merged_cusp = tet->cusp[v0];
dead_cusp = tet->cusp[v1];
}
else
{
merged_cusp = tet->cusp[v1];
dead_cusp = tet->cusp[v0];
}
if (merged_cusp==dead_cusp)
same_cusp = TRUE;
else same_cusp = FALSE;
if (same_cusp)
merged_cusp->euler_characteristic = merged_cusp->euler_characteristic - 2;
else if (merged_cusp->euler_characteristic==2 || dead_cusp->euler_characteristic==2)
merged_cusp->euler_characteristic = merged_cusp->euler_characteristic
+dead_cusp->euler_characteristic - 2;
else merged_cusp->euler_characteristic = merged_cusp->euler_characteristic
+dead_cusp->euler_characteristic;
merged_cusp->topology = unknown_topology;
if (same_cusp)
num_cone_points = merged_cusp->num_cone_points - 2;
else num_cone_points = merged_cusp->num_cone_points + dead_cusp->num_cone_points -2;
cone_points = NEW_ARRAY( num_cone_points, int );
num_cone_points = 0;
for(i=0;i<merged_cusp->num_cone_points;i++)
if (merged_cusp->cone_points[i]!=edge->singular_index)
cone_points[num_cone_points++] = merged_cusp->cone_points[i];
my_free(merged_cusp->cone_points);
if (!same_cusp)
{
dead_index = dead_cusp->index;
/* fix cusp fields */
for( tet0 = manifold->tet_list_begin.next;
tet0!=&manifold->tet_list_end;
tet0 = tet0->next )
for( i = 0; i < 4; i++ )
if (tet0->cusp[i] == dead_cusp)
tet0->cusp[i] = merged_cusp;
for(i=0;i<dead_cusp->num_cone_points;i++)
if (dead_cusp->cone_points[i]!=edge->singular_index)
cone_points[num_cone_points++] = dead_cusp->cone_points[i];
my_free(dead_cusp->cone_points);
REMOVE_NODE(dead_cusp);
my_free(dead_cusp);
}
/* install new cone points */
merged_cusp->cone_points = cone_points;
merged_cusp->num_cone_points = num_cone_points;
for( cusp = manifold->cusp_list_begin.next;
cusp!=&manifold->cusp_list_end;
cusp = cusp->next )
{
for (i=0;i < cusp->num_cone_points;i++)
if (cusp->cone_points[i] > edge->singular_index)
cusp->cone_points[i] = cusp->cone_points[i] - 1;
if (!same_cusp && cusp->index > dead_index)
cusp->index--;
}
for( edge3 = manifold->edge_list_begin.next;
edge3!=&manifold->edge_list_end;
edge3 = edge3->next )
if (edge3->is_singular && edge3->singular_index > edge->singular_index)
edge3->singular_index--;
edge->singular_index = -1;
edge->is_singular = FALSE;
edge->singular_order = 1;
manifold->num_singular_arcs--;
if (!same_cusp)
{
manifold->num_cusps--;
manifold->num_or_cusps--;
}
}
else /* creating_new_cusp == TRUE */
{
static Triangulation *try_Dirichlet_to_triangulation(
WEPolyhedron *polyhedron)
{
/*
* Implement Plan A as described above.
*/
Triangulation *triangulation;
WEEdge *edge,
*nbr_edge,
*mate_edge;
WEEdgeEnd end;
WEEdgeSide side;
Tetrahedron *new_tet;
FaceIndex f;
/*
* Don't attempt to triangulate an orbifold.
*/
if (singular_set_is_empty(polyhedron) == FALSE)
return NULL;
/*
* Set up the Triangulation.
*/
triangulation = NEW_STRUCT(Triangulation);
initialize_triangulation(triangulation);
/*
* Allocate and copy the name.
*/
triangulation->name = NEW_ARRAY(strlen(DEFAULT_NAME) + 1, char);
strcpy(triangulation->name, DEFAULT_NAME);
/*
* Allocate the Tetrahedra.
*/
triangulation->num_tetrahedra = 4 * polyhedron->num_edges;
for (edge = polyhedron->edge_list_begin.next;
edge != &polyhedron->edge_list_end;
edge = edge->next)
for (end = 0; end < 2; end++) /* = tail, tip */
for (side = 0; side < 2; side++) /* = left, right */
{
new_tet = NEW_STRUCT(Tetrahedron);
initialize_tetrahedron(new_tet);
INSERT_BEFORE(new_tet, &triangulation->tet_list_end);
edge->tet[end][side] = new_tet;
}
/*
* Initialize neighbors.
*/
for (edge = polyhedron->edge_list_begin.next;
edge != &polyhedron->edge_list_end;
edge = edge->next)
for (end = 0; end < 2; end++) /* = tail, tip */
for (side = 0; side < 2; side++) /* = left, right */
{
/*
* Neighbor[0] is associated to this same WEEdge.
* It lies on the same side (left or right), but
* at the opposite end (tail or tip).
*/
edge->tet[end][side]->neighbor[0] = edge->tet[!end][side];
/*
* Neighbor[1] lies on the same face of the Dirichlet
* domain, but at the "next side" of that face.
*/
nbr_edge = edge->e[end][side];
if (nbr_edge->v[!end] == edge->v[end])
/* edge and nbr_edge point in the same direction */
edge->tet[end][side]->neighbor[1] = nbr_edge->tet[!end][side];
else if (nbr_edge->v[end] == edge->v[end])
/* edge and nbr_edge point in opposite directions */
edge->tet[end][side]->neighbor[1] = nbr_edge->tet[end][!side];
else
uFatalError("Dirichlet_to_triangulation", "Dirichlet_conversion");
/*
* Neighbor[2] is associated to this same WEEdge.
* It lies at the same end (tail or tip), but
* on the opposite side (left or right).
*/
edge->tet[end][side]->neighbor[2] = edge->tet[end][!side];
/*
* Neighbor[3] lies on this face's "mate" elsewhere
* on the Dirichlet domain.
*/
mate_edge = edge->neighbor[side];
edge->tet[end][side]->neighbor[3] = mate_edge->tet
[edge->preserves_direction[side] ? end : !end ]
[edge->preserves_sides[side] ? side : !side];
}
/*
* Initialize all gluings to the identity.
*/
for (edge = polyhedron->edge_list_begin.next;
edge != &polyhedron->edge_list_end;
edge = edge->next)
for (end = 0; end < 2; end++) /* = tail, tip */
for (side = 0; side < 2; side++) /* = left, right */
for (f = 0; f < 4; f++)
edge->tet[end][side]->gluing[f] = IDENTITY_PERMUTATION;
/*
* Set up the EdgeClasses.
*/
create_edge_classes(triangulation);
orient_edge_classes(triangulation);
/*
* Attempt to orient the manifold.
*/
orient(triangulation);
/*
* Set up the Cusps, including "fake cusps" for the finite vertices.
* Then locate and remove the fake cusps. If the manifold is closed,
* drill out an arbitrary curve to express it as a Dehn filling.
* Finally, determine the topology of each cusp (torus or Klein bottle)
* and count them.
*/
create_cusps(triangulation);
mark_fake_cusps(triangulation);
peripheral_curves(triangulation);
remove_finite_vertices(triangulation);
count_cusps(triangulation);
/*
* Try to compute a hyperbolic structure, first for the unfilled
* manifold, and then for the closed manifold if appropriate.
*/
find_complete_hyperbolic_structure(triangulation);
do_Dehn_filling(triangulation);
/*
* If the manifold is hyperbolic, install a shortest basis on each cusp.
*/
if ( triangulation->solution_type[complete] == geometric_solution
|| triangulation->solution_type[complete] == nongeometric_solution)
install_shortest_bases(triangulation);
/*
* All done!
*/
return triangulation;
}
static void drill_tube(
Triangulation *manifold,
Tetrahedron *tet,
EdgeIndex e,
Boolean creating_new_cusp)
{
/*
* Insert a triangular-pillow-with-tunnel (as described at the top
* of this file) so as to connect the boundary component at one
* end of the given edge to the boundary component at the other end.
* The orientation on the triangular pillow will match the
* orientation on tet, so that the orientation on the manifold
* (if there is one) will be preserved. Edge orientations are also
* respected.
*/
VertexIndex v0,
v1,
v2,
vv0,
vv1,
vv2;
FaceIndex f,
ff;
Tetrahedron *nbr_tet,
*new_tet0,
*new_tet1;
Permutation gluing;
EdgeClass *edge0,
*edge1,
*edge2,
*new_edge;
Orientation edge_orientation0,
edge_orientation1,
edge_orientation2;
PeripheralCurve c;
Orientation h;
int num_strands,
intersection_number[2],
the_gcd;
Cusp *unique_cusp;
MatrixInt22 basis_change[1];
/*
* Relative to the orientation of tet, the vertices v0, v1 and v2
* are arranged in counterclockwise order around the face f.
*/
v0 = one_vertex_at_edge[e];
v1 = other_vertex_at_edge[e];
v2 = remaining_face[v1][v0];
f = remaining_face[v0][v1];
/*
* Note the matching face and its vertices.
*/
nbr_tet = tet->neighbor[f];
gluing = tet->gluing[f];
ff = EVALUATE(gluing, f);
vv0 = EVALUATE(gluing, v0);
vv1 = EVALUATE(gluing, v1);
vv2 = EVALUATE(gluing, v2);
/*
* Note the incident EdgeClasses (which may or may not be distinct).
*/
edge0 = tet->edge_class[e];
edge1 = tet->edge_class[edge_between_vertices[v1][v2]];
edge2 = tet->edge_class[edge_between_vertices[v2][v0]];
/*
* Construct the triangular-pillow-with-tunnel, as described
* at the top of this file.
*/
new_tet0 = NEW_STRUCT(Tetrahedron);
new_tet1 = NEW_STRUCT(Tetrahedron);
initialize_tetrahedron(new_tet0);
initialize_tetrahedron(new_tet1);
INSERT_BEFORE(new_tet0, &manifold->tet_list_end);
INSERT_BEFORE(new_tet1, &manifold->tet_list_end);
manifold->num_tetrahedra += 2;
new_edge = NEW_STRUCT(EdgeClass);
initialize_edge_class(new_edge);
INSERT_BEFORE(new_edge, &manifold->edge_list_end);
new_tet0->neighbor[0] = new_tet1;
new_tet0->neighbor[1] = NULL; /* assigned below */
new_tet0->neighbor[2] = NULL; /* assigned below */
new_tet0->neighbor[3] = new_tet1;
new_tet1->neighbor[0] = new_tet0;
new_tet1->neighbor[1] = new_tet1;
new_tet1->neighbor[2] = new_tet1;
new_tet1->neighbor[3] = new_tet0;
new_tet0->gluing[0] = CREATE_PERMUTATION(0, 0, 1, 2, 2, 1, 3, 3);
new_tet0->gluing[1] = 0x00; /* assigned below */
new_tet0->gluing[2] = 0x00; /* assigned below */
new_tet0->gluing[3] = CREATE_PERMUTATION(0, 1, 1, 0, 2, 2, 3, 3);
new_tet1->gluing[0] = CREATE_PERMUTATION(0, 0, 1, 2, 2, 1, 3, 3);
new_tet1->gluing[1] = CREATE_PERMUTATION(0, 0, 1, 2, 2, 1, 3, 3);
new_tet1->gluing[2] = CREATE_PERMUTATION(0, 0, 1, 2, 2, 1, 3, 3);
new_tet1->gluing[3] = CREATE_PERMUTATION(0, 1, 1, 0, 2, 2, 3, 3);
new_tet0->edge_class[0] = edge1;
new_tet0->edge_class[1] = edge1;
new_tet0->edge_class[2] = edge0;
new_tet0->edge_class[3] = edge2;
new_tet0->edge_class[4] = edge0;
new_tet0->edge_class[5] = edge0;
new_tet1->edge_class[0] = edge1;
new_tet1->edge_class[1] = edge1;
new_tet1->edge_class[2] = edge0;
new_tet1->edge_class[3] = new_edge;
new_tet1->edge_class[4] = edge0;
new_tet1->edge_class[5] = edge0;
edge0->order += 6;
edge1->order += 4;
edge2->order += 1;
new_edge->order = 1;
new_edge->incident_tet = new_tet1;
new_edge->incident_edge_index = 3;
edge_orientation0 = tet->edge_orientation[e];
edge_orientation1 = tet->edge_orientation[edge_between_vertices[v1][v2]];
edge_orientation2 = tet->edge_orientation[edge_between_vertices[v2][v0]];
new_tet0->edge_orientation[0] = edge_orientation1;
new_tet0->edge_orientation[1] = edge_orientation1;
new_tet0->edge_orientation[2] = edge_orientation0;
new_tet0->edge_orientation[3] = edge_orientation2;
new_tet0->edge_orientation[4] = edge_orientation0;
new_tet0->edge_orientation[5] = edge_orientation0;
new_tet1->edge_orientation[0] = edge_orientation1;
new_tet1->edge_orientation[1] = edge_orientation1;
new_tet1->edge_orientation[2] = edge_orientation0;
new_tet1->edge_orientation[3] = right_handed;
new_tet1->edge_orientation[4] = edge_orientation0;
new_tet1->edge_orientation[5] = edge_orientation0;
new_tet0->cusp[0] = tet->cusp[v0];
new_tet0->cusp[1] = tet->cusp[v0];
new_tet0->cusp[2] = tet->cusp[v0];
new_tet0->cusp[3] = tet->cusp[v2];
new_tet1->cusp[0] = tet->cusp[v0];
new_tet1->cusp[1] = tet->cusp[v0];
new_tet1->cusp[2] = tet->cusp[v0];
new_tet1->cusp[3] = tet->cusp[v2];
/*
* Install the triangular-pillow-with-tunnel.
*/
tet->neighbor[f] = new_tet0;
tet->gluing[f] = CREATE_PERMUTATION(f, 2, v0, 0, v1, 1, v2, 3);
new_tet0->neighbor[2] = tet;
new_tet0->gluing[2] = inverse_permutation[tet->gluing[f]];
nbr_tet->neighbor[ff] = new_tet0;
nbr_tet->gluing[ff] = CREATE_PERMUTATION(ff, 1, vv0, 0, vv1, 2, vv2, 3);
new_tet0->neighbor[1] = nbr_tet;
new_tet0->gluing[1] = inverse_permutation[nbr_tet->gluing[ff]];
/*
* Typically creating_new_cusp is FALSE, meaning that we are
* connecting a spherical boundary component to a torus or
* Klein bottle boundary component, and we simply extend the
* existing peripheral curves across the new tetrahedra.
*
* In the exceptional case that creating_new_cusp is TRUE,
* meaning that the manifold has no real cusps and we are
* connecting the "special fake cusp" to itself, we must
* install a meridian and longitude, and set up the Dehn filling.
*/
if (creating_new_cusp == FALSE)
{
/*
* Extend the peripheral curves across the boundary of the
* triangular-pillow-with-tunnel.
*
* Note: The orientations of new_tet0 and new_tet1 match that
* of tet, so the right_handed and left_handed sheets match up
* in the obvious way.
*/
for (c = 0; c < 2; c++) /* c = M, L */
for (h = 0; h < 2; h++) /* h = right_handed, left_handed */
{
num_strands = tet->curve[c][h][v0][f];
new_tet0->curve[c][h][0][2] = -num_strands;
new_tet0->curve[c][h][0][1] = +num_strands;
num_strands = tet->curve[c][h][v1][f];
new_tet0->curve[c][h][1][2] = -num_strands;
new_tet0->curve[c][h][1][0] = +num_strands;
new_tet1->curve[c][h][2][0] = -num_strands;
new_tet1->curve[c][h][2][1] = +num_strands;
new_tet1->curve[c][h][1][2] = -num_strands;
new_tet1->curve[c][h][1][0] = +num_strands;
new_tet0->curve[c][h][2][0] = -num_strands;
new_tet0->curve[c][h][2][1] = +num_strands;
num_strands = tet->curve[c][h][v2][f];
new_tet0->curve[c][h][3][2] = -num_strands;
new_tet0->curve[c][h][3][1] = +num_strands;
}
}
else /* creating_new_cusp == TRUE */
{
/*
* We have just installed a tube connecting the (unique)
* spherical "cusp" to itself, to convert it to a torus or
* Klein bottle.
*/
unique_cusp = tet->cusp[v0]->matching_cusp;
unique_cusp->is_complete = TRUE; /* to be filled below */
unique_cusp->index = 0;
unique_cusp->is_finite = FALSE;
manifold->num_cusps = 1;
/*
* Install an arbitrary meridian and longitude.
*/
peripheral_curves(manifold);
count_cusps(manifold);
/*
* Two sides of the (truncated) vertex 0 of new_tet0
* (namely the sides incident to faces 1 and 2 of new_tet0)
* define the Dehn filling curve by which we can recover
* the closed manifold. Count how many times the newly
* installed meridian and longitude cross this Dehn filling curve.
* To avoid messy questions about which sheet of the cusp's
* double cover we're on, use two (parallel) copies of the
* Dehn filling curve, one on each sheet of the cover.
* Ultimately we're looking for a linear combination of the
* meridian and longitude whose intersection number with
* the Dehn filling curve is zero, so it won't matter if
* we're off by a factor of two.
*/
for (c = 0; c < 2; c++) /* c = M, L */
{
intersection_number[c] = 0;
for (h = 0; h < 2; h++) /* h = right_handed, left_handed */
{
intersection_number[c] += new_tet0->curve[c][h][0][1];
intersection_number[c] += new_tet0->curve[c][h][0][2];
}
}
/*
* Use the intersection numbers to deduce
* the desired Dehn filling coefficients.
*/
the_gcd = gcd(intersection_number[M], intersection_number[L]);
unique_cusp->is_complete = FALSE;
unique_cusp->m = -intersection_number[L] / the_gcd;
unique_cusp->l = +intersection_number[M] / the_gcd;
/*
* Switch to a basis in which the Dehn filling curve is a meridian.
*/
unique_cusp->cusp_shape[initial] = Zero; /* force current_curve_basis() to ignore the cusp shape */
current_curve_basis(manifold, unique_cusp->index, basis_change[0]);
if (change_peripheral_curves(manifold, basis_change) != func_OK)
uFatalError("drill_tube", "finite_vertices");
}
}
