polychain_util_impl.hpp

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/*
 * Copyright (c) 2010-2015:  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__LIB_GRID__POLYCHAIN_UTIL_IMPL__
#define __H__LIB_GRID__POLYCHAIN_UTIL_IMPL__
 
#include "geom_obj_util/vertex_util.h"
 
namespace ug
{
 
template <class TEdgeIterator>
size_t
GetPolyChainType(Grid& grid, TEdgeIterator edgesBegin,
          TEdgeIterator edgesEnd,
          Grid::edge_traits::callback cbEdgeIsInPolyChain)
{
//  if the chain is empty, there's nothing to do
  if(edgesBegin == edgesEnd)
    return PCT_EMPTY;
 
//  check for each vertex to how many chain-edges it is connected
  size_t numBnd = 0;
  bool irregular = false;
  
  for(TEdgeIterator iter = edgesBegin; iter != edgesEnd; ++iter)
  {
    for(size_t i = 0; i < 2; ++i){
      Vertex* v = (*iter)->vertex(i);
      
      size_t counter = 0;
      for(Grid::AssociatedEdgeIterator aiter = grid.associated_edges_begin(v);
        aiter != grid.associated_edges_end(v); ++aiter)
      {
        if(cbEdgeIsInPolyChain(*aiter))
          ++counter;
      }
      
      if(counter == 0){
        throw(UGError("cbEdgeIsInPolyChain does not evaluate to true for "
                "edge between edgesBegin and edgesEnd."));
      }
                
      if(counter == 1)
        ++numBnd;
      else if(counter > 2)
        irregular = true;
    }
  }
  
//  prepare the return value
  size_t type = PCT_UNKNOWN;
  
  if(numBnd == 0)
    type = PCT_CLOSED;
  else if(numBnd < 3)
    type = PCT_OPEN;
  else
    type = PCT_SEPARATED;
 
  if(irregular)
    type |= PCT_IRREGULAR;
    
  return type;
}
          
template <class TEdgeIterator>
std::pair<Vertex*, Edge*>
GetFirstSectionOfPolyChain(Grid& grid, TEdgeIterator edgesBegin,
              TEdgeIterator edgesEnd,
              Grid::edge_traits::callback cbEdgeIsInPolyChain)
{
  if(edgesBegin == edgesEnd)
    return std::make_pair<Vertex*, Edge*>(NULL, NULL);
  
//  since we want to prefer vertices with local edge index 0, we'll first iterate
//  over the local indices of the edges
  for(size_t locInd = 0; locInd < 2; ++locInd){
  //  iterate through all edges.
    for(TEdgeIterator iter = edgesBegin; iter != edgesEnd; ++iter)
    {
      Edge* curEdge = *iter;
      Vertex* curVrt = curEdge->vertex(locInd);
      
    //  if curVrt is a boundary vertex of the given chain, then we're done.
      if(IsBoundaryVertex1D(grid, curVrt, cbEdgeIsInPolyChain)){
        return std::make_pair(curVrt, curEdge);
      }
    }
  }
  
  return std::make_pair((*edgesBegin)->vertex(0), *edgesBegin);
}
 
template <class TEdgeIter>
bool CreatePolyChain(std::vector<Vertex*>& polyChainOut, Grid& grid,
          TEdgeIter edgesBegin, TEdgeIter edgesEnd)
{
  polyChainOut.clear();
 
  grid.begin_marking();
 
//  mark and count edges
/*
  int numEdges = 0; // unused
*/
  for(TEdgeIter iter = edgesBegin; iter != edgesEnd; ++iter){
    grid.mark(*iter);
    /*
    ++numEdges; // s. the counter above and the check below
    */
  }
 
//TODO: handle open chains.
  Edge* actEdge = *edgesBegin;
  Vertex* actVrt = actEdge->vertex(1);
  polyChainOut.push_back(actEdge->vertex(0));
  grid.mark(actEdge->vertex(0));
  polyChainOut.push_back(actEdge->vertex(1));
  grid.mark(actEdge->vertex(1));
 
  bool bRunning = true;
  while(bRunning){
    bRunning = false;
  //  find a connected  unmarked vertex
    Grid::AssociatedEdgeIterator assEdgesEnd = grid.associated_edges_end(actVrt);
    for(Grid::AssociatedEdgeIterator eIter = grid.associated_edges_begin(actVrt);
      eIter != assEdgesEnd; ++eIter)
    {
      Edge* e = *eIter;
      if(grid.is_marked(e)){
      //  check whether the connected vertex is unmarked
        Vertex* cv = GetConnectedVertex(e, actVrt);
        if(!grid.is_marked(cv)){
        //  push it to the chain and mark it.
          grid.mark(cv);
          polyChainOut.push_back(cv);
        //  we're done with actVrt. cv will be the new actVrt
          actVrt = cv;
          bRunning = true;
          break;
        }
      }
    }
  }
 
  grid.end_marking();
/*
  if(polyChainOut.size() != numEdges) // s. the commented counter above
    return false;
*/
  return true;
}
 
}// end of namespace
 
#endif