delaunay_info_impl.h

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/*
 * Copyright (c) 2015:  G-CSC, Goethe University Frankfurt
 * Author: Sebastian Reiter
 * 
 * This file is part of UG4.
 * 
 * UG4 is free software: you can redistribute it and/or modify it under the
 * terms of the GNU Lesser General Public License version 3 (as published by the
 * Free Software Foundation) with the following additional attribution
 * requirements (according to LGPL/GPL v3 §7):
 * 
 * (1) The following notice must be displayed in the Appropriate Legal Notices
 * of covered and combined works: "Based on UG4 (www.ug4.org/license)".
 * 
 * (2) The following notice must be displayed at a prominent place in the
 * terminal output of covered works: "Based on UG4 (www.ug4.org/license)".
 * 
 * (3) The following bibliography is recommended for citation and must be
 * preserved in all covered files:
 * "Reiter, S., Vogel, A., Heppner, I., Rupp, M., and Wittum, G. A massively
 *   parallel geometric multigrid solver on hierarchically distributed grids.
 *   Computing and visualization in science 16, 4 (2013), 151-164"
 * "Vogel, A., Reiter, S., Rupp, M., Nägel, A., and Wittum, G. UG4 -- a novel
 *   flexible software system for simulating pde based models on high performance
 *   computers. Computing and visualization in science 16, 4 (2013), 165-179"
 * 
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
 * GNU Lesser General Public License for more details.
 */
 
#ifndef __H__UG_delaunay_info_impl
#define __H__UG_delaunay_info_impl
 
#include "lib_grid/algorithms/geom_obj_util/edge_util.h"
 
namespace ug{
 
template <class TAAPos> 
template <class TIter>
void DelaunayInfo<TAAPos>::
init_marks(TIter trisBegin, TIter trisEnd, bool pushFlipCandidates)
{
  using namespace std;
 
//  first mark all triangles and associated vertices with mark INNER
  for(TIter iter = trisBegin; iter != trisEnd; ++iter){
    Face* f = *iter;
    if(f->num_vertices() != 3)
      continue;
 
    set_mark(f, INNER);
    for(size_t i = 0; i < 3; ++i){
      set_mark(f->vertex(i), INNER);
    }
  }
 
//  Collect all candidates for flips (only edges with two neighbors, both marked).
  Grid::edge_traits::secure_container edges;
  for(TIter triIter = trisBegin; triIter != trisEnd; ++triIter){
    Face* t = *triIter;
    m_grid.associated_elements(edges, t);
    for(size_t i = 0; i < edges.size(); ++i){
      Edge* e = edges[i];
 
    //  treat edges only once
      if(mark(e) != NONE)
        continue;
 
    //  mark inner and outer segments
      if(m_cbConstrainedEdge(e)){
        set_mark(e, SEGMENT);
        set_mark(e->vertex(0), SEGMENT);
        set_mark(e->vertex(1), SEGMENT);
      }
      else{
        Face* nbrFaces[2];
        int numNbrs = GetAssociatedFaces(nbrFaces, m_grid, e, 2);
      //  two neighbors, both marked
        if(numNbrs == 2 && is_inner(nbrFaces[0])
          && is_inner(nbrFaces[1]))
        {
        //  the edge is a flip candidate
          if(pushFlipCandidates)
            push_candidate(e);
        }
        else{
        //  the edge lies on the rim and has to be marked as a segment
          set_mark(e, SEGMENT);
          set_mark(e->vertex(0), SEGMENT);
          set_mark(e->vertex(1), SEGMENT);
        }
      }
    }
  }
 
//todo: iterate over triangles again, this time examining their corners.
//    (use grid::mark to only visit each once).
//    Check for each whether it is connected to two segments with a smaller
//    angle than Pi/3. If this is the case, it will be marked as DART
  AAPos aaPos = position_accessor();
 
  m_grid.begin_marking();
  for(TIter triIter = trisBegin; triIter != trisEnd; ++triIter){
    Face* f = *triIter;
    Face::ConstVertexArray vrts = f->vertices();
    const size_t numVrts = f->num_vertices();
    for(size_t ivrt = 0; ivrt < numVrts; ++ivrt){
      Vertex* vrt = vrts[ivrt];
      if(m_grid.is_marked(vrt))
        continue;
      m_grid.mark(vrt);
      
      if(mark(vrt) != SEGMENT)
        continue;
 
      vector_t vrtPos = aaPos[vrt];
 
      bool searching = true;
      m_grid.associated_elements(edges, vrt);
      for(size_t iedge = 0; (iedge < edges.size()) && searching; ++iedge){
        Edge* edge = edges[iedge];
        if(mark(edge) != SEGMENT)
          continue;
 
        vector_t dir1;
        VecSubtract(dir1, aaPos[GetConnectedVertex(edge, vrt)], vrtPos);
 
      //  check angles between all segment-edges. If one is found which
      //  is smaller than PI/3, then the vertex will be marked as DART vertex.
        for(size_t iotherEdge = iedge + 1; iotherEdge < edges.size(); ++iotherEdge){
          Edge* otherEdge = edges[iotherEdge];
          if(mark(otherEdge) != SEGMENT)
            continue;
 
          vector_t dir2;
          VecSubtract(dir2, aaPos[GetConnectedVertex(otherEdge, vrt)], vrtPos);
 
          if(VecAngle(dir1, dir2) < PI / 3. + SMALL){
            searching = false;
            set_mark(vrt, DART);
            break;
          }
        }
      }
    }
  }
  m_grid.end_marking();
}
 
 
template <class TAAPos> 
template <class TElem>
bool DelaunayInfo<TAAPos>::
is_inner(TElem* e)
{
  Mark m = mark(e);
  return (m == INNER) || (m == NEW_INNER);
}
 
 
template <class TAAPos> 
template <class TElem>
bool DelaunayInfo<TAAPos>::
is_segment(TElem* e)
{
  Mark m = mark(e);
  return (m == SEGMENT) || (m == NEW_SEGMENT) || (m == DART) || (m == SHELL);
}
 
 
}// end of namespace
 
#endif  //__H__UG_delaunay_info_impl