NearestNeighbor.cpp

// Gmsh - Copyright (C) 1997-2016 C. Geuzaine, J.-F. Remacle
//
// See the LICENSE.txt file for license information. Please report all
// bugs and problems to the public mailing list <gmsh@onelab.info>.

#include "GmshConfig.h"
#include "NearestNeighbor.h"

#if defined(HAVE_ANN)
#include "ANN/ANN.h"
#endif

StringXNumber NearestNeighborOptions_Number[] = {
  {GMSH_FULLRC, "View", NULL, -1.},
};

extern "C"
{
  GMSH_Plugin *GMSH_RegisterNearestNeighborPlugin()
  {
    return new GMSH_NearestNeighborPlugin();
  }
}

std::string GMSH_NearestNeighborPlugin::getHelp() const
{
  return "Plugin(NearestNeighbor) computes the distance from each "
    "point in `View' to its nearest neighbor.\n\n"
    "If `View' < 0, the plugin is run on the current view.\n\n"
    "Plugin(NearestNeighbor) is executed in-place.";
}

int GMSH_NearestNeighborPlugin::getNbOptions() const
{
  return sizeof(NearestNeighborOptions_Number) / sizeof(StringXNumber);
}

StringXNumber *GMSH_NearestNeighborPlugin::getOption(int iopt)
{
  return &NearestNeighborOptions_Number[iopt];
}

PView *GMSH_NearestNeighborPlugin::execute(PView *v)
{
  int iView = (int)NearestNeighborOptions_Number[0].def;

  PView *v1 = getView(iView, v);
  if(!v1) return v;
  PViewData *data1 = v1->getData();

  int totpoints = data1->getNumPoints();
  if(!totpoints){
    Msg::Error("View[%d] contains no points", iView);
    return 0;
  }

#if defined(HAVE_ANN)
  ANNpointArray zeronodes = annAllocPts(totpoints, 3);
  int k = 0, step = 0;
  for(int ent = 0; ent < data1->getNumEntities(step); ent++){
    for(int ele = 0; ele < data1->getNumElements(step, ent); ele++){
      if(data1->skipElement(step, ent, ele)) continue;
      int numNodes = data1->getNumNodes(step, ent, ele);
      if(numNodes != 1) continue;
      data1->getNode(step, ent, ele, 0, zeronodes[k][0], zeronodes[k][1],
                     zeronodes[k][2]);
      k++;
    }
  }
  ANNkd_tree *kdtree = new ANNkd_tree(zeronodes, totpoints, 3);
  ANNidxArray index = new ANNidx[2];
  ANNdistArray dist = new ANNdist[2];

  v1->setChanged(true);
  for(int ent = 0; ent < data1->getNumEntities(step); ent++){
    for(int ele = 0; ele < data1->getNumElements(step, ent); ele++){
      if(data1->skipElement(step, ent, ele)) continue;
      int numNodes = data1->getNumNodes(step, ent, ele);
      if(numNodes != 1) continue;
      double xyz[3];
      data1->getNode(step, ent, ele, 0, xyz[0], xyz[1], xyz[2]);
      kdtree->annkSearch(xyz, 2, index, dist);
      data1->setValue(step, ent, ele, 0, 0, sqrt(dist[1]));
    }
  }

  delete kdtree;
  annDeallocPts(zeronodes);
  delete [] index;
  delete [] dist;
#else
  Msg::Error("Nearest neighbor computation requires ANN");
#endif

  data1->setName(v1->getData()->getName() + "_NearestNeighbor");
  data1->finalize();

  return v1;
}