CGAL: Access to Results of find_conflicts()

Question

So I am very confused about the find_conflicts function in CGAL. I thought I knew std::pair, and I thought I knew what was going on in find_conflicts(), but for the life of me, I am not sure how to access the results. I thought that the iterator that is passed to find_conflicts would be enough to then access the values directly. (i.e., I want to get at those facets that I put in the "vector facets,") and it appears as if I'm doing that because I can successfully

           typedef std::pair<std::vector<Facet>, std::vector<Cell> > FacetAndCell;


            *  *  *


            Cell_handle cell = T.locate(curr_point);
            std::vector<Facet> facets;

            T.find_conflicts(curr_point, cell, std::back_inserter(facets), CGAL::Emptyset_iterator());

            CGAL::First_of_pair_property_map<FacetAndCell> my_p_map();

            Delaunay::Finite_facets_iterator ff_iter;
            std::vector<Facet>::iterator facet_iter;

            // Here, what I'm trying to achieve is figuring out which of the facets 
            // in conflict are finite.  I had wanted to use some kind of test like 
            // "is_infinite()" on the facet at hand, but this isn't available for 
            // a facet out of context of the triangulation it's part of.

            for(facet_iter = facets.begin(); facet_iter != facets.end(); facet_iter++){
                for(ff_iter = T.finite_facets_begin(); ff_iter != T.finite_facets_end(); ff_iter++){

                    // Since I get an error that facet_iter is actually of type pair, I thought this would work, but it doesn't.
                    // ERROR!
                    cout << facet_iter->first << endl;

                    // This works, which is what led me to believe I was comparing one facet to another facet.
                    /*
                    if(*facet_iter == *ff_iter){
                        cout << "Finite facet!" << endl;
                        break;
                    }*/
                }
            }

In summary:

1) Overall, I want to know which facets from the result of find_conflicts() were finite. If there is an easier way to do this, feel free to let me know.

2) Otherwise, the more specific problem here is that I need to get at that vector of facets that results from find_conflicts() and then get at the vertices of each facet. Am I supposed to be working with the returned "pair" of cells and facets or can I access the vector directly, like I'm trying to do?

Help, please, thanks.

score 0 · Answer 1 · edited May 23 '17 at 11:49

0

For finiteness testing, use is_infinite(). See http://doc.cgal.org/latest/Triangulation_3/classCGAL_1_1Triangulation__3.html#af024721d3ae4b9327ffe442fb828935c

Otherwise, maybe you are confused because the Facet type is a typedef to a pair (unfortunately).

PS: alternatively, you can use Marc Glisse's suggestion in your other question (using locate(midpoint(p, sphere center))). It might be easier. CGAL Using Locate() to Find Cell on Triangulation Surface

edited May 23 '17 at 11:49

Community

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answered Jun 23 '14 at 23:02

Sylvain Pion

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Ahhh, yes. You're good at figuring out my real misunderstanding. It was the latter; so a Facet is described by a cell and a vertex index of that cell that dictates which cell-vertex the facet opposes...a facet is necessarily a triangle in a 3D Delaunay triangulation, right? – kdottiemo Jun 25 '14 at 20:28

CGAL: Access to Results of find_conflicts()

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