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Merge pull request #2598 from sloriot/BGL-fix_export_to_nef 

Correctly handle faces with more than one cc of the boundary
This commit is contained in:
Laurent Rineau 2017-12-05 17:57:59 +01:00
parent e35cb74938 67ab9d124d
commit a84a0b686b
1 changed files with 119 additions and 15 deletions
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134
BGL/include/CGAL/boost/graph/convert_nef_polyhedron_to_polygon_mesh.h
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@ -27,6 +27,11 @@
#include <CGAL/circulator.h>
#include <CGAL/Cartesian_converter.h>
#include <boost/unordered_map.hpp>
#include <CGAL/Constrained_Delaunay_triangulation_2.h>
#include <CGAL/Triangulation_2_projection_traits_3.h>
#include <CGAL/Triangulation_vertex_base_with_info_2.h>
#include <CGAL/Triangulation_face_base_with_info_2.h>
namespace CGAL{
@ -64,6 +69,12 @@ struct Shell_vertex_index_visitor
{}
};
struct FaceInfo2
{
FaceInfo2() : visited(false) {}
bool visited;
};
//Visitor used to collect polygons
template <class Nef_polyhedron>
struct Shell_polygons_visitor
@ -89,21 +100,113 @@ struct Shell_polygons_visitor
typename Nef_polyhedron::Halffacet_const_handle f = opposite_facet->twin();
typename Nef_polyhedron::SHalfedge_around_facet_const_circulator
sfc1(f->facet_cycles_begin());
if (cpp11::next(f->facet_cycles_begin())==f->facet_cycles_end())
{
// create a new polygon
polygons.push_back( std::vector<std::size_t>() );
fc = f->facet_cycles_begin();
se = typename Nef_polyhedron::SHalfedge_const_handle(fc);
CGAL_assertion(se!=0);
typename Nef_polyhedron::SHalfedge_around_facet_const_circulator
hc_start(se), hc_end(hc_start);
// insert the vertex indices of the new polygon
CGAL_For_all(hc_start,hc_end)
polygons.back().push_back(vertex_indices[hc_start->source()->center_vertex()]);
if (!is_marked)
std::reverse(polygons.back().begin(), polygons.back().end());
}
else{
typedef typename Nef_polyhedron::Kernel Kernel;
typedef Triangulation_2_projection_traits_3<Kernel> P_traits;
typedef Triangulation_vertex_base_with_info_2<std::size_t, P_traits> Vb;
typedef Triangulation_face_base_with_info_2<FaceInfo2,P_traits> Fbb;
typedef Constrained_triangulation_face_base_2<P_traits,Fbb> Fb;
typedef Triangulation_data_structure_2<Vb,Fb> TDS;
typedef Exact_predicates_tag Itag;
typedef Constrained_Delaunay_triangulation_2<P_traits, TDS, Itag> CDT;
// create a new polygon
polygons.push_back( std::vector<std::size_t>() );
fc = f->facet_cycles_begin();
se = typename Nef_polyhedron::SHalfedge_const_handle(fc);
CGAL_assertion(se!=0);
typename Nef_polyhedron::SHalfedge_around_facet_const_circulator
hc_start(se), hc_end(hc_start);
// insert the vertex indices of the new polygon
CGAL_For_all(hc_start,hc_end)
polygons.back().push_back(vertex_indices[hc_start->source()->center_vertex()]);
if (!is_marked)
std::reverse(polygons.back().begin(), polygons.back().end());
P_traits p_traits(opposite_facet->plane().orthogonal_vector());
CDT cdt(p_traits);
// insert each connected component of the boundary of the face as
// a polygonal constraints
typename Nef_polyhedron::Halffacet_cycle_const_iterator
hfc_start=f->facet_cycles_begin(), hfc_end=f->facet_cycles_end();
CGAL_For_all(hfc_start, hfc_end)
{
fc=hfc_start;
se = typename Nef_polyhedron::SHalfedge_const_handle(fc);
CGAL_assertion(se!=0);
typename Nef_polyhedron::SHalfedge_around_facet_const_circulator
hc_start(se), hc_end(hc_start);
// collect contour vertices
std::vector< typename CDT::Vertex_handle > polygon;
CGAL_For_all(hc_start,hc_end)
{
typename CDT::Vertex_handle vh=cdt.insert(hc_start->source()->center_vertex()->point());
vh->info() = vertex_indices[hc_start->source()->center_vertex()];
polygon.push_back(vh);
}
std::size_t nb_constraints = polygon.size();
polygon.push_back(polygon.front());
for(std::size_t i=0; i<nb_constraints; ++i)
cdt.insert_constraint(polygon[i], polygon[i+1]);
}
//look for a triangle inside the domain of the face
typename CDT::Face_handle fh = cdt.infinite_face();
fh->info().visited=true;
std::vector<typename CDT::Edge> queue;
for (int i=0; i<3; ++i)
queue.push_back(typename CDT::Edge(fh, i) );
while(true)
{
typename CDT::Edge e = queue.back();
queue.pop_back();
e=cdt.mirror_edge(e);
if (e.first->info().visited) continue;
if (cdt.is_constrained(e))
{
queue.clear();
queue.push_back(e);
break;
}
else
{
for(int i=1; i<3; ++i)
{
typename CDT::Edge candidate(e.first, (e.second+i)%3);
if (!candidate.first->neighbor(candidate.second)->info().visited)
queue.push_back( candidate );
}
e.first->info().visited=true;
}
}
// now extract triangles inside the face
while(!queue.empty())
{
typename CDT::Edge e = queue.back();
queue.pop_back();
if (e.first->info().visited) continue;
e.first->info().visited=true;
polygons.resize(polygons.size()+1);
if (is_marked)
for (int i=2; i>=0; --i)
polygons.back().push_back(e.first->vertex(i)->info());
else
for (int i=0; i<3; ++i)
polygons.back().push_back(e.first->vertex(i)->info());
for(int i=1; i<3; ++i)
{
typename CDT::Edge candidate(e.first, (e.second+i)%3);
if (!cdt.is_constrained(candidate) &&
!candidate.first->neighbor(candidate.second)->info().visited)
{
queue.push_back( cdt.mirror_edge(candidate) );
}
}
}
}
}
void visit(typename Nef_polyhedron::SFace_const_handle)
@ -141,7 +244,8 @@ void collect_polygon_mesh_info(
/// \ingroup PkgBGL
/// Converts an objet of type `Nef_polyhedron_3` into a polygon mesh model of `MutableFaceGraph`.
/// Note that contrary to `Nef_polyhedron_3::convert_to_polyhedron()`, the output is not triangulated.
/// Note that contrary to `Nef_polyhedron_3::convert_to_polyhedron()`, the output is not triangulated
/// (but faces with more than one connected component of the boundary).
/// The polygon mesh can be triangulated using the function `triangulate_faces()`.
/// \pre `Polygon_mesh` must have an internal point property map with value type being `Nef_polyhedron_3::Point_3`.
/// \pre `nef.simple()`