# usecases/c/UsesCase_MEDmesh_14.c

    /*  This file is part of MED.
     *
     *  COPYRIGHT (C) 1999 - 2012  EDF R&D, CEA/DEN
     *  MED is free software: 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.
     *
     *  MED 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.
     *
     *  You should have received a copy of the GNU Lesser General Public License
     *  along with MED.  If not, see <http://www.gnu.org/licenses/>.
     */

    /*
     *  Use case 14 : read a 2D unstructured mesh with 2 polygons
     */

    #include <med.h>
    #define MESGERR 1
    #include <med_utils.h>

    #include <string.h>

    int main (int argc, char **argv) {
      med_idt fid;
      const char meshname[MED_NAME_SIZE+1] = "2D unstructured mesh";
      char meshdescription[MED_COMMENT_SIZE+1]="";
      med_int meshdim;
      med_int spacedim;
      med_sorting_type sortingtype;
      med_int nstep;
      med_mesh_type meshtype;
      med_axis_type axistype;
      char axisname[2*MED_SNAME_SIZE+1]="";
      char unitname[2*MED_SNAME_SIZE+1]="";
      char dtunit[MED_SNAME_SIZE+1]="";
      med_float *coordinates = NULL;
      med_int nnodes = 0;
      med_int npoly = 0;
      med_int indexsize;
      med_int *index = NULL;
      med_int *connectivity = NULL;
      med_int connectivitysize;
      med_bool coordinatechangement;
      med_bool geotransformation;
      int i;
      int k,ind1,ind2;
      int ret=-1;

      /* open MED file with READ ONLY access mode */
      fid = MEDfileOpen("UsesCase_MEDmesh_13.med",MED_ACC_RDONLY);
      if (fid < 0) {
        MESSAGE("ERROR : open file in READ ONLY ACCESS mode ...");
        goto ERROR;
      }

      /*
       * ... we know that the MED file has only one mesh,
       * a real code working would check ...
       */

      /* read mesh informations : mesh dimension, space dimension ... */
      if (MEDmeshInfoByName(fid, meshname, &spacedim, &meshdim, &meshtype, meshdescription,
                            dtunit, &sortingtype, &nstep, &axistype, axisname, unitname) < 0) {
        MESSAGE("ERROR : mesh info ...");
        goto ERROR;
      }

      /* read how many nodes in the mesh */
      if ((nnodes = MEDmeshnEntity(fid, meshname, MED_NO_DT, MED_NO_IT, MED_NODE, MED_POINT1,
                                   MED_COORDINATE, MED_NO_CMODE,&coordinatechangement,
                                   &geotransformation)) < 0) {
        MESSAGE("ERROR : number of nodes ...");
        goto ERROR;
      }

      /*
       * ... we know that we only have MED_POLYGON celles in the mesh,
       * a real code working would check all MED geometry cell types ...
       */

      /* How many polygon in the mesh in nodal connectivity mode */
      /* For the polygons, we get the size of array index */
      if ((indexsize = MEDmeshnEntity(fid,meshname,MED_NO_DT,MED_NO_IT,
                                      MED_CELL,MED_POLYGON,MED_INDEX_NODE,MED_NODAL,
                                      &coordinatechangement,
                                      &geotransformation)) < 0) {
        MESSAGE("ERROR : read number of polygon ...");
        goto ERROR;
      }
      npoly = indexsize-1;

      /* how many nodes for the polygon connectivity ? */
      if ((connectivitysize = MEDmeshnEntity(fid,meshname,MED_NO_DT,MED_NO_IT,
                                             MED_CELL,MED_POLYGON,MED_CONNECTIVITY,MED_NODAL,
                                             &coordinatechangement,
                                             &geotransformation)) < 0) {
        MESSAGE("ERROR : read connevity size ...");
        goto ERROR;
        }

      /* read mesh nodes coordinates */
      if ((coordinates = (med_float*) malloc(sizeof(med_float)*nnodes*spacedim)) == NULL) {
        MESSAGE("ERROR : memory allocation ...");
        goto ERROR;
      }

      if (MEDmeshNodeCoordinateRd(fid, meshname, MED_NO_DT, MED_NO_IT, MED_FULL_INTERLACE,
                                  coordinates) < 0) {
        MESSAGE("ERROR : nodes coordinates ...");
        free(coordinates);
        goto ERROR;
      }
      free(coordinates);

      /* read polygons connectivity */
      index = (med_int *) malloc(sizeof(med_int)*indexsize);
      connectivity = (med_int *) malloc(sizeof(med_int)*connectivitysize);

      if (MEDmeshPolygonRd(fid,meshname,MED_NO_DT,MED_NO_IT,MED_CELL,MED_NODAL,
                           index,connectivity) < 0) {
        MESSAGE("ERROR : read polygon connectivity ...");
        free(index);
        free(connectivity);
        goto ERROR;
      }
      free(index);
      free(connectivity);

      /*
       * ... we know that the family number of nodes and elements is 0, a real working would check ...
       */

      ret=0;
     ERROR:

      /* close MED file */
      if (MEDfileClose(fid) < 0) {
        MESSAGE("ERROR : close file");
        ret=-1;
      }

      return ret;
    }