mirror of https://github.com/CGAL/cgal
214 lines
6.4 KiB
C++
214 lines
6.4 KiB
C++
#ifndef CGAL_BOOST_GRAPH_HELPERS_H
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#define CGAL_BOOST_GRAPH_HELPERS_H
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#include <boost/foreach.hpp>
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namespace CGAL {
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template <typename FaceGraph>
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bool is_border(typename boost::graph_traits<FaceGraph>::halfedge_descriptor hd, const FaceGraph& g)
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{
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return face(hd,g) == boost::graph_traits<FaceGraph>::null_face();
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}
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/*!
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returns `true` if there are no
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border edges.
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*/
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template <typename FaceGraph>
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bool is_closed(const FaceGraph& g)
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{
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typedef typename boost::graph_traits<FaceGraph>::halfedge_descriptor halfedge_descriptor;
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BOOST_FOREACH(halfedge_descriptor hd, halfedges(g)){
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if(is_border(hd,g)){
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return false;
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}
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}
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return true;
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}
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template <typename FaceGraph>
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bool is_bivalent(typename boost::graph_traits<FaceGraph>::halfedge_descriptor hd, const FaceGraph& g)
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{
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return hd == opposite(next(opposite(next(hd,g),g),g),g);
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}
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/*!
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returns `true` if all
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vertices have exactly two incident edges.
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*/
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template <typename FaceGraph>
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bool is_pure_bivalent(const FaceGraph& g)
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{
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typedef typename boost::graph_traits<FaceGraph>::vertex_descriptor vertex_descriptor;
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typedef typename boost::graph_traits<FaceGraph>::halfedge_descriptor halfedge_descriptor;
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BOOST_FOREACH(vertex_descriptor vd, vertices(g)){
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halfedge_descriptor hd = halfedge(vd,g);
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if((hd == boost::graph_traits<FaceGraph>::null_halfedge()) ||
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(! is_bivalent(hd,g))){
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return false;
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}
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}
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return true;
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}
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template <typename FaceGraph>
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bool is_trivalent(typename boost::graph_traits<FaceGraph>::halfedge_descriptor hd, const FaceGraph& g)
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{
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return hd == opposite(next(opposite(next(opposite(next(hd,g),g),g),g),g),g);
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}
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/*!
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returns `true` if all
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vertices have exactly three incident edges.
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*/
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template <typename FaceGraph>
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bool is_pure_trivalent(const FaceGraph& g)
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{
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typedef typename boost::graph_traits<FaceGraph>::vertex_descriptor vertex_descriptor;
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typedef typename boost::graph_traits<FaceGraph>::halfedge_descriptor halfedge_descriptor;
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BOOST_FOREACH(vertex_descriptor vd, vertices(g)){
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halfedge_descriptor hd = halfedge(vd,g);
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if((hd == boost::graph_traits<FaceGraph>::null_halfedge()) ||
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(! is_trivalent(hd,g))){
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return false;
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}
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}
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return true;
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}
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/*!
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returns `true` iff the connected component denoted by `h` is a triangle.
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\pre `g` must be valid.
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*/
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template <typename FaceGraph>
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bool is_triangle(typename boost::graph_traits<FaceGraph>::halfedge_descriptor hd, const FaceGraph& g)
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{
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typedef typename boost::graph_traits<FaceGraph>::halfedge_descriptor halfedge_descriptor;
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halfedge_descriptor beg = hd;
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if(is_border(hd,g)) return false;
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for(int i=0; i<3;i++){
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if(! is_border(opposite(hd,g),g)) return false;
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hd = next(hd,g);
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}
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return next(hd,g)== beg;
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}
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/*!
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returns `true` iff the face is a triangle, that is it has three incident halfedges.
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*/
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template <typename FaceGraph>
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bool is_triangle(typename boost::graph_traits<FaceGraph>::face_descriptor fd, const FaceGraph& g)
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{
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typedef typename boost::graph_traits<FaceGraph>::halfedge_descriptor halfedge_descriptor;
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halfedge_descriptor hd = halfedge(fd,g);
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return hd == next(next(next(hd,g),g),g);
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}
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/*!
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returns `true` if all faces are triangles.
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*/
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template <typename FaceGraph>
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bool is_pure_triangle(const FaceGraph& g)
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{
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typedef typename boost::graph_traits<FaceGraph>::face_descriptor face_descriptor;
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BOOST_FOREACH(face_descriptor fd, faces(g)){
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if(! is_triangle(fd,g)){
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return false;
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}
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}
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return true;
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}
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/*!
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returns `true` iff the connected component denoted by `h` is a quadrilateral.
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*/
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template <typename FaceGraph>
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bool is_quad(typename boost::graph_traits<FaceGraph>::halfedge_descriptor hd, const FaceGraph& g)
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{
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typedef typename boost::graph_traits<FaceGraph>::halfedge_descriptor halfedge_descriptor;
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halfedge_descriptor beg = hd;
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if(is_border(hd,g)) return false;
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for(int i=0; i<4;i++){
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if(! is_border(opposite(hd,g),g)) return false;
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hd = next(hd,g);
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}
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return next(hd,g)== beg;
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}
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/*!
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returns `true` iff the face is a quad, that is it has four incident halfedges.
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*/
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template <typename FaceGraph>
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bool is_quad(typename boost::graph_traits<FaceGraph>::face_descriptor fd, const FaceGraph& g)
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{
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typedef typename boost::graph_traits<FaceGraph>::halfedge_descriptor halfedge_descriptor;
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halfedge_descriptor hd = halfedge(fd,g);
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return hd == next(next(next(next(hd,g),g),g),g);
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}
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/*!
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returns `true` if all faces are quadrilaterals.
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*/
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template <typename FaceGraph>
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bool is_pure_quad(const FaceGraph& g)
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{
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typedef typename boost::graph_traits<FaceGraph>::face_descriptor face_descriptor;
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BOOST_FOREACH(face_descriptor fd, faces(g)){
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if(! is_quad(fd,g)){
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return false;
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}
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}
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return true;
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}
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/*!
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returns `true` iff the connected component denoted by `h` is a tetrahedron.
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*/
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template <typename FaceGraph>
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bool is_tetrahedron( typename boost::graph_traits<FaceGraph>::halfedge_descriptor h1, const FaceGraph& g)
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{
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typedef typename boost::graph_traits<FaceGraph>::halfedge_descriptor halfedge_descriptor;
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halfedge_descriptor h2 = next(h1,g);
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halfedge_descriptor h3 = next(h2,g);
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halfedge_descriptor h4 = next(opposite(h1,g),g );
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halfedge_descriptor h5 = next(opposite(h2,g),g );
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halfedge_descriptor h6 = next(opposite(h3,g),g );
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// check halfedge combinatorics.
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// at least three edges at vertices 1, 2, 3.
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if ( h4 == opposite(h3,g) ) return false;
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if ( h5 == opposite(h1,g) ) return false;
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if ( h6 == opposite(h2,g) ) return false;
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// exact three edges at vertices 1, 2, 3.
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if ( next(opposite(h4,g),g) != opposite(h3,g) ) return false;
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if ( next(opposite(h5,g),g) != opposite(h1,g) ) return false;
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if ( next(opposite(h6,g),g) != opposite(h2,g) ) return false;
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// three edges at v4.
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if ( opposite(next(h4,g),g) != h5 ) return false;
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if ( opposite(next(h5,g),g) != h6 ) return false;
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if ( opposite(next(h6,g),g) != h4 ) return false;
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// All facets are triangles.
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if ( next(next(next(h1,g),g),g) != h1 ) return false;
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if ( next(next(next(h4,g),g),g) != h4 ) return false;
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if ( next(next(next(h5,g),g),g) != h5 ) return false;
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if ( next(next(next(h6,g),g),g) != h6 ) return false;
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// all edges are non-border edges.
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if ( is_border(h1,g) ) return false; // implies h2 and h3
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if ( is_border(h4,g) ) return false;
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if ( is_border(h5,g) ) return false;
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if ( is_border(h6,g) ) return false;
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return true;
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}
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} // namespace CGAL
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#endif // CGAL_BOOST_GRAPH_HELPERS_H
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