get_boundary.h

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#pragma once
 
#include <vector>
 
namespace pcl
{
  namespace geometry
  {
    /** \brief Get a collection of boundary half-edges for the input mesh.
      * \param[in] mesh The input mesh.
      * \param[out] boundary_he_collection Collection of boundary half-edges. Each element in the vector is one connected boundary. The whole boundary is the union of all elements.
      * \param [in] expected_size If you already know the size of the longest boundary you can tell this here. Defaults to 3 (minimum possible boundary).
      * \author Martin Saelzle
      * \ingroup geometry
      */
    template <class MeshT> void
    getBoundBoundaryHalfEdges (const MeshT&                                   mesh,
                               std::vector <typename MeshT::HalfEdgeIndices>& boundary_he_collection,
                               const std::size_t                                   expected_size = 3)
    {
      using Mesh = MeshT;
      using HalfEdgeIndex = typename Mesh::HalfEdgeIndex;
      using HalfEdgeIndices = typename Mesh::HalfEdgeIndices;
      using IHEAFC = typename Mesh::InnerHalfEdgeAroundFaceCirculator;
 
      boundary_he_collection.clear ();
 
      HalfEdgeIndices boundary_he; boundary_he.reserve (expected_size);
      std::vector <bool> visited (mesh.sizeEdges (), false);
      IHEAFC circ, circ_end;
 
      for (HalfEdgeIndex i (0); i<HalfEdgeIndex (mesh.sizeHalfEdges ()); ++i)
      {
        if (mesh.isBoundary (i) && !visited [pcl::geometry::toEdgeIndex (i).get ()])
        {
          boundary_he.clear ();
 
          circ     = mesh.getInnerHalfEdgeAroundFaceCirculator (i);
          circ_end = circ;
          do
          {
            visited [pcl::geometry::toEdgeIndex (circ.getTargetIndex ()).get ()] = true;
            boundary_he.push_back (circ.getTargetIndex ());
          } while (++circ != circ_end);
 
          boundary_he_collection.push_back (boundary_he);
        }
      }
    }
 
  } // End namespace geometry
} // End namespace pcl