/**
* Insert a point so that is splits an existing edge. This function
* assumes that the point is on the edge itself and between its
* end-points.
* If the edge being split is constrained, then the function returns a
* list containing both parts resulted from the splitting. In that case,
* THE RETURNED EDGES MUST BE UNREFERENCED!
*/
GList*
p2tr_cdt_split_edge (P2trCDT *self,
P2trEdge *e,
P2trPoint *C)
{
/* W
* /|\
* / | \
* / | \ E.Mirror.Tri: YXW
* X*---*---*Y E: X->Y
* \ |C / E.Tri: XYV
* \ | /
* \|/
* V
*/
P2trPoint *X = P2TR_EDGE_START (e), *Y = e->end;
P2trPoint *V = (e->tri != NULL) ? p2tr_triangle_get_opposite_point(e->tri, e) : NULL;
P2trPoint *W = (e->mirror->tri != NULL) ? p2tr_triangle_get_opposite_point (e->mirror->tri, e->mirror) : NULL;
gboolean constrained = e->constrained;
P2trEdge *XC, *CY;
GList *new_tris = NULL, *fan = NULL, *new_edges = NULL;
p2tr_edge_remove (e);
XC = p2tr_mesh_new_edge (self->mesh, X, C, constrained);
CY = p2tr_mesh_new_edge (self->mesh, C, Y, constrained);
fan = p2tr_utils_new_reversed_pointer_list (4, W, X, V, Y);
new_tris = p2tr_cdt_triangulate_fan (self, C, fan);
g_list_free (fan);
/* Now make this a CDT again
* The new triangles will be unreffed by the flip_fix function, which
* is good since we receive them with an extra reference!
*/
p2tr_cdt_flip_fix (self, new_tris);
g_list_free (new_tris);
if (constrained)
{
/* If this was a subsegment, then both parts of the subsegment
* should exist */
if (p2tr_edge_is_removed (XC) || p2tr_edge_is_removed (CY))
p2tr_exception_geometric ("Subsegments gone!");
else
{
new_edges = g_list_prepend (new_edges, CY);
new_edges = g_list_prepend (new_edges, XC);
}
}
else
{
p2tr_edge_unref (XC);
p2tr_edge_unref (CY);
}
p2tr_cdt_on_new_point (self, C);
return new_edges;
}
void
p2tr_cdt_validate_unused (P2trCDT* self)
{
P2trEdge *ed;
P2trTriangle *tri;
P2trHashSetIter iter;
p2tr_hash_set_iter_init (&iter, self->mesh->edges);
while (p2tr_hash_set_iter_next (&iter, (gpointer*)&ed))
{
g_assert (ed->mirror != NULL);
g_assert (! p2tr_edge_is_removed (ed));
}
p2tr_hash_set_iter_init (&iter, self->mesh->triangles);
while (p2tr_hash_set_iter_next (&iter, (gpointer*)&tri))
g_assert (! p2tr_triangle_is_removed (tri));
}
void
p2tr_cdt_flip_fix (P2trCDT *self,
P2trVEdgeSet *candidates)
{
P2trEdge *edge;
P2trVEdge *vedge;
while (p2tr_vedge_set_pop (candidates, &vedge))
{
if (! p2tr_vedge_try_get_and_unref (vedge, &edge))
continue;
if (! edge->constrained
/* TODO: we probably don't need this check... */
&& ! p2tr_edge_is_removed (edge))
{
/* If the edge is not constrained, then it should be
* a part of two triangles */
P2trPoint *A = P2TR_EDGE_START(edge), *B = edge->end;
P2trPoint *C1 = p2tr_triangle_get_opposite_point (edge->tri, edge, FALSE);
P2trPoint *C2 = p2tr_triangle_get_opposite_point (edge->mirror->tri, edge->mirror, FALSE);
P2trEdge *flipped = p2tr_cdt_try_flip (self, edge);
if (flipped != NULL)
{
p2tr_vedge_set_add (candidates, p2tr_point_get_edge_to (A, C1, TRUE));
p2tr_vedge_set_add (candidates, p2tr_point_get_edge_to (A, C2, TRUE));
p2tr_vedge_set_add (candidates, p2tr_point_get_edge_to (B, C1, TRUE));
p2tr_vedge_set_add (candidates, p2tr_point_get_edge_to (B, C2, TRUE));
p2tr_edge_unref (flipped);
}
}
p2tr_edge_unref (edge);
}
}
