mirror of https://github.com/CGAL/cgal
242 lines
8.1 KiB
C++
242 lines
8.1 KiB
C++
// compute self-intersection of a CGAL triangle polyhedron mesh
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// original code from Lutz Kettner
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#ifndef CGAL_SELF_INTERSECTION_POLYHEDRON_3
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#define CGAL_SELF_INTERSECTION_POLYHEDRON_3
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#include <CGAL/box_intersection_d.h>
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#include <CGAL/intersections.h>
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#include <CGAL/Bbox_3.h>
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#include <vector>
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#include <exception>
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#include <boost/function_output_iterator.hpp>
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namespace CGAL {
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namespace internal {
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template <class Polyhedron, class Kernel, class OutputIterator>
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struct Intersect_facets
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{
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// typedefs
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typedef typename Kernel::Segment_3 Segment;
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typedef typename Kernel::Triangle_3 Triangle;
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typedef typename Polyhedron::Facet_const_handle Facet_const_handle;
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typedef typename Polyhedron::Halfedge_const_handle Halfedge_const_handle;
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typedef typename CGAL::Box_intersection_d::Box_with_handle_d<double, 3, Facet_const_handle> Box;
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// members
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mutable OutputIterator m_iterator;
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typename Kernel::Construct_segment_3 segment_functor;
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typename Kernel::Construct_triangle_3 triangle_functor;
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typename Kernel::Do_intersect_3 do_intersect_3_functor;
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Intersect_facets(OutputIterator it, const Kernel& kernel)
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: m_iterator(it),
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segment_functor(kernel.construct_segment_3_object()),
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triangle_functor(kernel.construct_triangle_3_object()),
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do_intersect_3_functor(kernel.do_intersect_3_object())
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{ }
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void operator()(const Box* b,
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const Box* c) const
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{
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Halfedge_const_handle h = b->handle()->halfedge();
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// check for shared egde --> no intersection
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if(h->opposite()->facet() == c->handle() ||
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h->next()->opposite()->facet() == c->handle() ||
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h->next()->next()->opposite()->facet() == c->handle())
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return;
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// check for shared vertex --> maybe intersection, maybe not
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Halfedge_const_handle g = c->handle()->halfedge();
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Halfedge_const_handle v;
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if(h->vertex() == g->vertex())
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v = g;
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if(h->vertex() == g->next()->vertex())
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v = g->next();
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if(h->vertex() == g->next()->next()->vertex())
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v = g->next()->next();
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if(v == Halfedge_const_handle())
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{
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h = h->next();
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if(h->vertex() == g->vertex())
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v = g;
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if(h->vertex() == g->next()->vertex())
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v = g->next();
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if(h->vertex() == g->next()->next()->vertex())
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v = g->next()->next();
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if(v == Halfedge_const_handle())
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{
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h = h->next();
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if(h->vertex() == g->vertex())
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v = g;
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if(h->vertex() == g->next()->vertex())
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v = g->next();
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if(h->vertex() == g->next()->next()->vertex())
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v = g->next()->next();
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}
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}
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if(v != Halfedge_const_handle())
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{
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// found shared vertex:
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CGAL_assertion(h->vertex() == v->vertex());
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// geometric check if the opposite segments intersect the triangles
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Triangle t1 = triangle_functor( h->vertex()->point(), h->next()->vertex()->point(), h->next()->next()->vertex()->point());
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Triangle t2 = triangle_functor( v->vertex()->point(), v->next()->vertex()->point(), v->next()->next()->vertex()->point());
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Segment s1 = segment_functor( h->next()->vertex()->point(), h->next()->next()->vertex()->point());
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Segment s2 = segment_functor( v->next()->vertex()->point(), v->next()->next()->vertex()->point());
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if(do_intersect_3_functor(t1,s2))
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{
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*m_iterator++ = std::make_pair(b->handle(), c->handle());
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}
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else if(do_intersect_3_functor(t2,s1))
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{
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*m_iterator++ = std::make_pair(b->handle(), c->handle());
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}
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return;
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}
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// check for geometric intersection
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Triangle t1 = triangle_functor( h->vertex()->point(), h->next()->vertex()->point(), h->next()->next()->vertex()->point());
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Triangle t2 = triangle_functor( g->vertex()->point(), g->next()->vertex()->point(), g->next()->next()->vertex()->point());
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if(do_intersect_3_functor(t1, t2))
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{
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*m_iterator++ = std::make_pair(b->handle(), c->handle());
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}
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} // end operator ()
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}; // end struct Intersect_facets
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struct Throw_at_output {
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class Throw_at_output_exception: public std::exception
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{ };
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template<class T>
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void operator()(const T& /* t */) const {
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throw Throw_at_output_exception();
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}
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};
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}// namespace internal
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////////////////////////////////////////////////////////////////////////////////////
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/*
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/// Geometric traits concept for the functions `self_intersect`
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concept SelfIntersectionTraits{
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/// @name Geometric Types
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/// @{
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/// 3D point type
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typedef unspecified_type Point_3;
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/// 3D triangle type
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typedef unspecified_type Triangle_3;
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/// 3D segment type
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typedef unspecified_type Segment_3;
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/// @}
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/// @name Functors
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/// @{
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/// Functor constructing triangles. It provides `Triangle_3 operator() const(const Point_3&, const Point_3&, const Point_3&)
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typedef unspecified_type Construct_triangle_3;
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/// Functor constructing segments. It provides `Segment_3 operator() const(const Point_3&, const Point_3&)
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typedef unspecified_type Construct_segment_3;
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/// Functor testing intersections between triangles and segment. It provides `bool operator() const (const Triangle_3&, const Segment_3&)` and `bool operator() const (const Triangle_3&, const Triangle_3&)`
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typedef unspecified_type Do_intersect_3;
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/// @}
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/// @name Functions
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/// @{
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Construct_triangle_3 construct_triangle_3_object() const;
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Construct_segment_3 construct_segment_3_object() const;
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Do_intersect_3 do_intersect_3_object() const;
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/// @}
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};
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*/
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////////////////////////////////////////////////////////////////////////////////////
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/**
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* Detects and reports self-intersections of a triangulated polyhedral surface
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* @pre @a p.is_pure_triangle()
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*
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* @tparam GeomTraits a model of `SelfIntersectionTraits`
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* @tparam Polyhedron a \cgal polyhedron
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* @tparam OutputIterator Output iterator accepting objects of type `std::pair<Polyhedron::Facet_const_handle, Polyhedron::Facet_const_handle>`
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*
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* @param polyhedron polyhedron to be checked
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* @param out all pairs of non-adjacent facets intersecting are put in it
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*
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* @return out
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*
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* \TODO Doc: move SelfIntersectionTraits concept to appropriate location.
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*/
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template <class GeomTraits, class Polyhedron, class OutputIterator>
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OutputIterator self_intersect(const Polyhedron& polyhedron, OutputIterator out, const GeomTraits& geom_traits = GeomTraits())
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{
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CGAL_assertion(polyhedron.is_pure_triangle());
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typedef typename Polyhedron::Facet_const_iterator Facet_const_iterator;
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typedef typename Polyhedron::Facet_const_handle Facet_const_handle;
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typedef typename CGAL::Box_intersection_d::Box_with_handle_d<double, 3, Facet_const_handle> Box;
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// make one box per facet
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std::vector<Box> boxes;
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boxes.reserve(polyhedron.size_of_facets());
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Facet_const_iterator f;
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for(f = polyhedron.facets_begin();
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f != polyhedron.facets_end();
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f++)
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boxes.push_back(Box( f->halfedge()->vertex()->point().bbox() +
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f->halfedge()->next()->vertex()->point().bbox() +
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f->halfedge()->next()->next()->vertex()->point().bbox(),
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f));
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// generate box pointers
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std::vector<const Box*> box_ptr;
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box_ptr.reserve(polyhedron.size_of_facets());
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typename std::vector<Box>::iterator b;
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for(b = boxes.begin();
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b != boxes.end();
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b++)
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box_ptr.push_back(&*b);
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// compute self-intersections filtered out by boxes
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internal::Intersect_facets<Polyhedron,GeomTraits,OutputIterator> intersect_facets(out, geom_traits);
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std::ptrdiff_t cutoff = 2000;
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CGAL::box_self_intersection_d(box_ptr.begin(), box_ptr.end(),intersect_facets,cutoff);
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return intersect_facets.m_iterator;
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}
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/**
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* Checks if a polyhedron is self-intersecting
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* @pre @a p.is_pure_triangle()
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*
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* @tparam GeomTraits a model of `SelfIntersectionTraits`
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* @tparam Polyhedron a %CGAL polyhedron
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*
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* @param polyhedron polyhedron to be tested
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*
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* @return true if `polyhedron` is self-intersecting
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*/
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template <class GeomTraits, class Polyhedron>
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bool self_intersect(const Polyhedron& polyhedron, const GeomTraits& geom_traits = GeomTraits())
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{
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try
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{
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typedef boost::function_output_iterator<internal::Throw_at_output> OutputIterator;
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self_intersect<GeomTraits>(polyhedron, OutputIterator(), geom_traits);
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}
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catch( internal::Throw_at_output::Throw_at_output_exception& )
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{ return true; }
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return false;
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}
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}// namespace CGAL
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#endif // CGAL_SELF_INTERSECTION_POLYHEDRON_3
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