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