trimesht.cc

penMesh is a generic and efficient data structure for representing and manipulating polygonal meshes

  // handle boundary cases
  if (!vl.is_valid())
    vlv1 = prev_halfedge_handle(halfedge_handle(v1));
  if (!vr.is_valid())
    vrv1 = prev_halfedge_handle(halfedge_handle(v1));


  // split vertex v1 into edge v0v1
  v0v1 = insert_edge(v0, vlv1, vrv1);


  return v0v1;
}


//-----------------------------------------------------------------------------


template <class Kernel>
typename TriMeshT<Kernel>::HalfedgeHandle
TriMeshT<Kernel>::
insert_loop(HalfedgeHandle _hh)
{
  HalfedgeHandle  h0(_hh);
  HalfedgeHandle  o0(opposite_halfedge_handle(h0));

  VertexHandle    v0(to_vertex_handle(o0));
  VertexHandle    v1(to_vertex_handle(h0));

  HalfedgeHandle  h1 = new_edge(v1, v0);
  HalfedgeHandle  o1 = opposite_halfedge_handle(h1);

  FaceHandle      f0 = face_handle(h0);
  FaceHandle      f1 = This::new_face();



  // halfedge -> halfedge
  set_next_halfedge_handle(prev_halfedge_handle(h0), o1);
  set_next_halfedge_handle(o1, next_halfedge_handle(h0));
  set_next_halfedge_handle(h1, h0);
  set_next_halfedge_handle(h0, h1);


  // halfedge -> face
  set_face_handle(o1, f0);
  set_face_handle(h0, f1);
  set_face_handle(h1, f1);


  // face -> halfedge
  set_halfedge_handle(f1, h0);
  if (f0.is_valid())
    set_halfedge_handle(f0, o1);


  // vertex -> halfedge
  adjust_outgoing_halfedge(v0);
  adjust_outgoing_halfedge(v1);


  return h1;
}


//-----------------------------------------------------------------------------


template <class Kernel>
typename TriMeshT<Kernel>::HalfedgeHandle
TriMeshT<Kernel>::
insert_edge(VertexHandle   _vh,
      HalfedgeHandle _h0,
      HalfedgeHandle _h1)
{
  assert(_h0.is_valid() && _h1.is_valid());

  VertexHandle  v0 = _vh;
  VertexHandle  v1 = to_vertex_handle(_h0);

  assert( v1 == to_vertex_handle(_h1));

  HalfedgeHandle v0v1 = new_edge(v0, v1);
  HalfedgeHandle v1v0 = opposite_halfedge_handle(v0v1);



  // vertex -> halfedge
  set_halfedge_handle(v0, v0v1);
  set_halfedge_handle(v1, v1v0);


  // halfedge -> halfedge
  set_next_halfedge_handle(v0v1, next_halfedge_handle(_h0));
  set_next_halfedge_handle(_h0, v0v1);
  set_next_halfedge_handle(v1v0, next_halfedge_handle(_h1));
  set_next_halfedge_handle(_h1, v1v0);


  // halfedge -> vertex
  for (VertexIHalfedgeIter vih_it(vih_iter(v0)); vih_it; ++vih_it)
    set_vertex_handle(vih_it.handle(), v0);


  // halfedge -> face
  set_face_handle(v0v1, face_handle(_h0));
  set_face_handle(v1v0, face_handle(_h1));


  // face -> halfedge
  if (face_handle(v0v1).is_valid())
    set_halfedge_handle(face_handle(v0v1), v0v1);
  if (face_handle(v1v0).is_valid())
    set_halfedge_handle(face_handle(v1v0), v1v0);


  // vertex -> halfedge
  adjust_outgoing_halfedge(v0);
  adjust_outgoing_halfedge(v1);


  return v0v1;
}


//-----------------------------------------------------------------------------


template <class Impl>
bool
TriMeshT<Impl>::
is_flip_ok(EdgeHandle _eh) const
{
  // boundary edges cannot be flipped
  if (is_boundary(_eh)) return false;


  HalfedgeHandle hh = halfedge_handle(_eh, 0);
  HalfedgeHandle oh = halfedge_handle(_eh, 1);


  // check if the flipped edge is already present
  // in the mesh

  VertexHandle ah = to_vertex_handle(next_halfedge_handle(hh));
  VertexHandle bh = to_vertex_handle(next_halfedge_handle(oh));

  if (ah == bh)   // this is generally a bad sign !!!
    return false;

  for (ConstVertexVertexIter vvi(*this, ah); vvi; ++vvi)
    if (vvi.handle() == bh)
      return false;

  return true;
}


//-----------------------------------------------------------------------------


template <class Impl>
void
TriMeshT<Impl>::
flip(EdgeHandle _eh)
{
  // CAUTION : Flipping a halfedge may result in
  // a non-manifold mesh, hence check for yourself
  // whether this operation is allowed or not!
  assert(is_flip_ok(_eh));//let's make it sure it is actually checked
  assert(!is_boundary(_eh));

  HalfedgeHandle a0 = halfedge_handle(_eh, 0);
  HalfedgeHandle b0 = halfedge_handle(_eh, 1);

  HalfedgeHandle a1 = next_halfedge_handle(a0);
  HalfedgeHandle a2 = next_halfedge_handle(a1);

  HalfedgeHandle b1 = next_halfedge_handle(b0);
  HalfedgeHandle b2 = next_halfedge_handle(b1);

  VertexHandle   va0 = to_vertex_handle(a0);
  VertexHandle   va1 = to_vertex_handle(a1);

  VertexHandle   vb0 = to_vertex_handle(b0);
  VertexHandle   vb1 = to_vertex_handle(b1);

  FaceHandle     fa  = face_handle(a0);
  FaceHandle     fb  = face_handle(b0);

  set_vertex_handle(a0, va1);
  set_vertex_handle(b0, vb1);

  set_next_halfedge_handle(a0, a2);
  set_next_halfedge_handle(a2, b1);
  set_next_halfedge_handle(b1, a0);

  set_next_halfedge_handle(b0, b2);
  set_next_halfedge_handle(b2, a1);
  set_next_halfedge_handle(a1, b0);

  set_face_handle(a1, fb);
  set_face_handle(b1, fa);

  set_halfedge_handle(fa, a0);
  set_halfedge_handle(fb, b0);

  if (halfedge_handle(va0) == b0)
    set_halfedge_handle(va0, a1);
  if (halfedge_handle(vb0) == a0)
    set_halfedge_handle(vb0, b1);
}


//-----------------------------------------------------------------------------


template <class Impl>
void
TriMeshT<Impl>::
split(EdgeHandle _eh, VertexHandle _vh)
{
  HalfedgeHandle h0 = halfedge_handle(_eh, 0);
  HalfedgeHandle o0 = halfedge_handle(_eh, 1);

  VertexHandle   v2 = to_vertex_handle(o0);

  HalfedgeHandle e1 = new_edge(_vh, v2);
  HalfedgeHandle t1 = opposite_halfedge_handle(e1);

  FaceHandle     f0 = face_handle(h0);
  FaceHandle     f3 = face_handle(o0);

  set_halfedge_handle(_vh, h0);
  set_vertex_handle(o0, _vh);

  if (!is_boundary(h0))
  {
    HalfedgeHandle h1 = next_halfedge_handle(h0);
    HalfedgeHandle h2 = next_halfedge_handle(h1);

    VertexHandle v1 = to_vertex_handle(h1);

    HalfedgeHandle e0 = new_edge(_vh, v1);
    HalfedgeHandle t0 = opposite_halfedge_handle(e0);

    FaceHandle f1 = This::new_face();
    set_halfedge_handle(f0, h0);
    set_halfedge_handle(f1, h2);

    set_face_handle(h1, f0);
    set_face_handle(t0, f0);
    set_face_handle(h0, f0);

    set_face_handle(h2, f1);
    set_face_handle(t1, f1);
    set_face_handle(e0, f1);

    set_next_halfedge_handle(h0, h1);
    set_next_halfedge_handle(h1, t0);
    set_next_halfedge_handle(t0, h0);

    set_next_halfedge_handle(e0, h2);
    set_next_halfedge_handle(h2, t1);
    set_next_halfedge_handle(t1, e0);
  }
  else
  {
    set_next_halfedge_handle(prev_halfedge_handle(h0), t1);
    set_next_halfedge_handle(t1, h0);
    // halfedge handle of _vh already is h0
  }


  if (!is_boundary(o0))
  {
    HalfedgeHandle o1 = next_halfedge_handle(o0);
    HalfedgeHandle o2 = next_halfedge_handle(o1);

    VertexHandle v3 = to_vertex_handle(o1);

    HalfedgeHandle e2 = new_edge(_vh, v3);
    HalfedgeHandle t2 = opposite_halfedge_handle(e2);

    FaceHandle f2 = This::new_face();
    set_halfedge_handle(f2, o1);
    set_halfedge_handle(f3, o0);

    set_face_handle(o1, f2);
    set_face_handle(t2, f2);
    set_face_handle(e1, f2);

    set_face_handle(o2, f3);
    set_face_handle(o0, f3);
    set_face_handle(e2, f3);

    set_next_halfedge_handle(e1, o1);
    set_next_halfedge_handle(o1, t2);
    set_next_halfedge_handle(t2, e1);

    set_next_halfedge_handle(o0, e2);
    set_next_halfedge_handle(e2, o2);
    set_next_halfedge_handle(o2, o0);
  }
  else
  {
    set_next_halfedge_handle(e1, next_halfedge_handle(o0));
    set_next_halfedge_handle(o0, e1);
    set_halfedge_handle(_vh, e1);
  }

  if (halfedge_handle(v2) == h0)
    set_halfedge_handle(v2, t1);
}

//-----------------------------------------------------------------------------


#if OM_OUT_OF_CLASS_TEMPLATE
template <typename Kernel_>
template <typename OtherMesh>
TriMeshT<Kernel_>&
TriMeshT<Kernel_>::
assign(const OtherMesh& _rhs)
#  include "PolyMeshT_assign.hh"
#endif

//=============================================================================
} // namespace OpenMesh
//=============================================================================