// Flip an edge, work only in 2D and 3D
Dart_handle
flip_edge (LCC & m, Dart_handle d)
{
CGAL_assertion ( !m.is_free(d,2) );
CGAL_assertion ( !m.is_free(d,1) && !m.is_free(d,0) );
CGAL_assertion ( !m.is_free(m.beta(d,2), 0) && !m.is_free(m.beta(d, 2), 1) );
if (!m.is_removable<1>(d)) return LCC::null_handle;
Dart_handle d1 = m.beta(d,1);
Dart_handle d2 = m.beta(d,2,0);
CGAL_assertion ( !m.is_free(d1,1) && !m.is_free(d2,0) );
Dart_handle d3 = m.beta(d1,1);
Dart_handle d4 = m.beta(d2, 0);
// We isolated the edge
m.basic_link_beta_1(m.beta(d,0), m.beta(d,2,1));
m.basic_link_beta_0(m.beta(d,1), m.beta(d,2,0));
if ( !m.is_free(d,3) )
{
m.basic_link_beta_0(m.beta(d,0,3), m.beta(d,2,1,3));
m.basic_link_beta_1(m.beta(d,1,3), m.beta(d,2,0,3));
}
// Then we push the two extremities.
m.basic_link_beta_0(d3, d);
m.basic_link_beta_0(d2, m.beta(d,2));
m.link_beta_1(d4, d);
m.link_beta_1(d1, m.beta(d,2));
if ( !m.is_free(d,3) )
{
m.basic_link_beta_0(m.beta(d4,3), m.beta(d,3));
m.basic_link_beta_0(m.beta(d1,3), m.beta(d,2,3));
m.link_beta_1(m.beta(d3,3), m.beta(d,3));
m.link_beta_1(m.beta(d2,3), m.beta(d,2,3));
}
// CGAL::remove_cell<LCC,1>(m, d);
// insert_cell_1_in_cell_2(m, d1, d1->beta(1)->beta(1));
return d;
}
// Subdivide each facet of the lcc by using sqrt(3)-subdivision.
void
subdivide_lcc_3 (LCC & m)
{
if (m.number_of_darts () == 0)
return;
LCC::size_type mark = m.get_new_mark ();
LCC::size_type treated = m.get_new_mark ();
m.negate_mark (mark); // All the old darts are marked in O(1).
// 1) We smoth the old vertices.
std::vector <std::pair<Point_3, Dart_handle> > vertices; // smooth the old vertices
vertices.reserve (m.number_of_attributes<0> ()); // get intermediate space
std::transform (m.vertex_attributes().begin (),
m.vertex_attributes().end (),
std::back_inserter (vertices),
Smooth_old_vertex (m, mark));
// 2) We subdivide each facet.
m.negate_mark (treated); // All the darts are marked in O(1).
unsigned int nb = 0;
for (LCC::Dart_range::iterator it (m.darts().begin ());
m.number_of_marked_darts (treated) > 0; ++it)
{
++nb;
if (m.is_marked (it, treated))
{
// We unmark the darts of the facet to process only once dart/facet.
CGAL::unmark_cell < LCC, 2 > (m, it, treated);
// We triangulate the facet.
m.insert_barycenter_in_cell<2>(it);
}
}
CGAL_assertion (m.is_whole_map_unmarked (treated));
CGAL_assertion (m.is_valid ());
m.free_mark (treated);
// 3) We update the coordinates of old vertices.
for (std::vector<std::pair<Point_3, Dart_handle> >::iterator
vit=vertices.begin(); vit!=vertices.end(); ++vit)
{
m.point(vit->second)=vit->first;
}
// 4) We flip all the old edges.
m.negate_mark (mark); // Now only new darts are marked.
Dart_handle d2 =LCC::null_handle;
for (LCC::Dart_range::iterator it (m.darts().begin ());
it != m.darts().end ();)
{
d2 = it++;
if (!m.is_marked (d2, mark)) // This is an old dart.
{
// We process only the last dart of a same edge.
if (!m.is_free(d2,2) && (m.beta(d2,2,3)==m.beta(d2,3,2)))
{
if (m.is_marked(m.beta(d2,2), mark) &&
(m.is_free(d2,3) ||
(m.is_marked(m.beta(d2,3), mark) &&
m.is_marked(m.beta(d2,2,3), mark))))
{
flip_edge (m, d2);
m.mark(d2, mark);
}
else
m.mark (d2, mark);
}
else
m.mark (d2, mark);
}
}
CGAL_assertion (m.is_whole_map_marked (mark));
m.free_mark (mark);
CGAL_postcondition ( m.is_valid ());
}
