intersections.hh

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// -*- tab-width: 4; indent-tabs-mode: nil; c-basic-offset: 2 -*-
// vi: set et ts=4 sw=2 sts=2:
#ifndef DUNE_MMESH_GRID_INTERSECTIONS_HH
#define DUNE_MMESH_GRID_INTERSECTIONS_HH
 
#include <unordered_set>
 
// Dune MMesh includes
#include <dune/mmesh/grid/entity.hh>
#include <dune/mmesh/grid/leafiterator.hh>
#include <dune/mmesh/grid/pointfieldvector.hh>
#include <dune/mmesh/misc/twistutility.hh>
 
// local includes
 
namespace Dune {
 
// External forward declarations
template <class Grid>
struct HostGridAccess;
 
template <class GridImp>
class MMeshLeafIntersection {
  friend class MMeshLeafIntersectionIterator<GridImp>;
 
  friend struct HostGridAccess<typename std::remove_const<GridImp>::type>;
 
  enum { dim = GridImp::dimension };
 
  enum { dimworld = GridImp::dimensionworld };
 
  // The type used to store coordinates
  typedef typename GridImp::ctype ctype;
 
  typedef typename GridImp::template HostGridEntity<0> HostGridEntity;
  typedef typename GridImp::template HostGridEntity<1> HostLeafIntersection;
 
 public:
  enum { dimension = GridImp::dimension };
  enum { dimensionworld = GridImp::dimensionworld };
  typedef typename GridImp::template Codim<1>::Geometry Geometry;
  typedef typename GridImp::template Codim<1>::LocalGeometry LocalGeometry;
  typedef typename GridImp::template Codim<1>::LocalGeometry::Implementation
      LocalGeometryImpl;
  typedef typename GridImp::template Codim<0>::Entity Entity;
  typedef FieldVector<ctype, dimworld> NormalVector;
 
  MMeshLeafIntersection() {}
 
  MMeshLeafIntersection(const GridImp* mMesh, const HostGridEntity& hostEntity,
                        const int index)
      : mMesh_(mMesh), hostIntersection_(hostEntity, index) {}
 
  MMeshLeafIntersection(const GridImp* mMesh,
                        HostLeafIntersection&& hostIntersection)
      : mMesh_(mMesh), hostIntersection_(std::move(hostIntersection)) {}
 
  bool equals(const MMeshLeafIntersection& other) const {
    return hostIntersection_ == other.hostIntersection_;
  }
 
  Entity inside() const {
    return MMeshEntity<0, dim, GridImp>(mMesh_, hostIntersection_.first);
  }
 
  Entity outside() const {
    assert(neighbor());
    auto neighborHostEntity =
        (hostIntersection_.first)->neighbor(hostIntersection_.second);
    return MMeshEntity<0, dim, GridImp>(mMesh_, neighborHostEntity);
  }
 
  bool boundary() const {
    auto neighborHostEntity =
        (hostIntersection_.first)->neighbor(hostIntersection_.second);
    return mMesh_->getHostGrid().is_infinite(neighborHostEntity);
  }
 
  NormalVector centerUnitOuterNormal() const {
    return unitOuterNormal(FieldVector<ctype, dim - 1>(0));
  }
 
  bool neighbor() const { return !boundary(); }
 
  std::size_t boundarySegmentIndex() const {
    HostGridEntity cell = hostIntersection_.first;
    const auto& facetIdx = hostIntersection_.second;
 
    std::vector<std::size_t> vertices;
    for (std::size_t i = 0; i < dim; ++i)
      vertices.push_back(
          cell->vertex((facetIdx + i + 1) % (dim + 1))->info().id);
    std::sort(vertices.begin(), vertices.end());
 
    auto it = mMesh_->boundarySegments().find(vertices);
    if (it == mMesh_->boundarySegments().end()) return 0;  // default to 0
 
    return it->second;
  }
 
  std::size_t boundaryId() const {
    auto it = mMesh_->boundaryIds().find(boundarySegmentIndex());
    if (it == mMesh_->boundaryIds().end()) return 0;  // default
 
    return it->second;
  }
 
  bool conforming() const {
    // we are always conforming
    return true;
  }
 
  GeometryType type() const { return GeometryTypes::simplex(dim - 1); }
 
  LocalGeometry geometryInInside() const {
    LocalGeometryImpl impl(indexInInside());
    return LocalGeometry(impl);
  }
 
  LocalGeometry geometryInOutside() const {
    assert(neighbor());
    LocalGeometryImpl impl(indexInOutside());
    return LocalGeometry(impl);
  }
 
  Geometry geometry() const { return Geometry(hostIntersection_); }
 
  int indexInInside() const {
    return MMeshImpl::cgalFacetToDuneFacet<dim, HostLeafIntersection>(
        hostIntersection_);
  }
 
  int indexInOutside() const {
    const auto& neighbor =
        hostIntersection_.first->neighbor(hostIntersection_.second);
    const auto& second = mMesh_->getHostGrid().mirror_index(
        hostIntersection_.first, hostIntersection_.second);
    HostLeafIntersection facetFromOutside({neighbor, second});
    return MMeshImpl::cgalFacetToDuneFacet<dim, HostLeafIntersection>(
        facetFromOutside);
  }
 
  FieldVector<ctype, GridImp::dimensionworld> outerNormal(
      const FieldVector<ctype, GridImp::dimension - 1>& local) const {
    return integrationOuterNormal(local);
  }
 
  template <int d = dim>
  typename std::enable_if_t<d == 2, NormalVector> integrationOuterNormal(
      const FieldVector<ctype, dim - 1>& local) const {
    HostGridEntity face = hostIntersection_.first;
    const auto& edgeIdx = hostIntersection_.second;
 
    const auto& p1 = face->vertex(face->cw(edgeIdx))->point();
    const auto& p2 = face->vertex(face->ccw(edgeIdx))->point();
 
    return NormalVector({p1.y() - p2.y(), -p1.x() + p2.x()});
  }
 
  template <int d = dim>
  typename std::enable_if_t<d == 3, NormalVector> integrationOuterNormal(
      const FieldVector<ctype, dim - 1>& local) const {
    HostGridEntity cell = hostIntersection_.first;
    const auto& facetIdx = hostIntersection_.second;
 
    const auto& p1 = cell->vertex((facetIdx + 1) % 4)->point();
    const auto& p2 = cell->vertex((facetIdx + 2) % 4)->point();
    const auto& p3 = cell->vertex((facetIdx + 3) % 4)->point();
 
    return makeFieldVector((facetIdx % 2 == 0) ? CGAL::normal(p1, p2, p3)
                                               : CGAL::normal(p1, p3, p2));
  }
 
  FieldVector<ctype, GridImp::dimensionworld> unitOuterNormal(
      const FieldVector<ctype, GridImp::dimension - 1>& local) const {
    NormalVector n = integrationOuterNormal(local);
    n /= n.two_norm();
    return n;
  }
 
  const HostLeafIntersection& getHostIntersection() const {
    return hostIntersection_;
  }
 
 private:
  const GridImp* mMesh_;
  HostLeafIntersection hostIntersection_;
};
 
}  // namespace Dune
 
#endif