calculate_vertices_tangent.hpp

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// Copyright (c) 2012-2019 University of Lyon and CNRS (France).
// All rights reserved.
//
// This file is part of MEPP2; you can redistribute it and/or modify
// it under the terms of the GNU Lesser General Public License as
// published by the Free Software Foundation; either version 3 of
// the License, or (at your option) any later version.
//
// This file is provided AS IS with NO WARRANTY OF ANY KIND, INCLUDING THE
// WARRANTY OF DESIGN, MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE.
#pragma once
 
#include <boost/graph/graph_traits.hpp>
 
#include "FEVV/Wrappings/Geometry_traits.h"
#include "FEVV/Operators/Generic/Manifold/calculate_face_tangent.hpp"
#include "FEVV/Filters/Generic/normalize_vector_map.h"
 
 
namespace FEVV {
namespace Filters {
 
template< typename HalfedgeGraph,
          typename PointMap,
          typename VertexUVMap,
          typename VertexTangentMap >
void
calculate_vertices_tangent(const HalfedgeGraph &g,
                           const PointMap &pm,
                           const VertexUVMap &vum, 
                           VertexTangentMap &vtm)
{
  using GeometryTraits = FEVV::Geometry_traits< HalfedgeGraph >;
  using Vector = typename GeometryTraits::Vector;
 
  using GraphTraits = typename boost::graph_traits< HalfedgeGraph >;
  using face_iterator = typename GraphTraits::face_iterator;
 
  using halfedge_descriptor =
      typename boost::graph_traits< HalfedgeGraph >::halfedge_descriptor;
 
  const GeometryTraits gt(g);
 
  face_iterator fb, fe;
  for(boost::tie(fb, fe) = faces(g); fb != fe; ++fb)
  {
    halfedge_descriptor half_edge = halfedge(*fb, g);
 
    const Vector uv1 = get(vum, target(half_edge, g));
    const Vector uv2 = get(vum, source(half_edge, g));
    const Vector uv3 = get(vum, target(next(half_edge, g), g));
 
    Operators::calculate_face_tangent(*fb, g, pm, uv1, uv2, uv3, vtm);
 
    // RM: may be better to use
    //   CGAL::halfedges_around_source(typename boost::graph_traits< Graph
    //   >::vertex_descriptor v, const Graph &g)
    //   ->
    //   https://doc.cgal.org/latest/BGL/group__PkgBGLIterators.html#gac257da1842bab20293c1db108cda75e5
    // and to compute tangent with each pair of halfedges
  }
 
  Filters::normalize_vector_map_vertices(g, vtm);
}
 
} // namespace Filters
} // namespace FEVV