# usecases/c/UsesCase_MEDmesh_16.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/>.
     */

    /*
     *  How to create an unstructured mesh with polygons
     *
     *  Use case 16 : read a 2D unstructured mesh with 2 polyhedrons
     */

    #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] = "3D 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[3*MED_SNAME_SIZE+1];
      char unitname[3*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 faceIndexSize;
      med_int *index = NULL;
      med_int *faceindex = NULL;
      med_int *connectivity = NULL;
      med_int connectivitysize;
      med_bool coordinatechangement;
      med_bool geotransformation;
      int i;
      int k,ind1,ind2;
      int j, jind1,jind2;

      /* open MED file with READ ONLY access mode */
      fid = MEDfileOpen("./UsesCase_MEDmesh_15.med",MED_ACC_RDONLY);
      if (fid < 0) {
        MESSAGE("ERROR : open file in READ ONLY ACCESS mode ...");
        return -1;
      }

      /*
       * ... 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 ...");
        return -1;
      }

      /* 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 ...");
        return -1;
      }

      /*
       * ... we know that we only have MED_POLYHEDRON cells 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_POLYHEDRON,MED_INDEX_FACE,MED_NODAL,
              &coordinatechangement,
              &geotransformation)) < 0) {
        MESSAGE("ERROR : read number of polyedron ...");
        return -1;
      }
      npoly = indexsize-1;
      ISCRUTE(npoly);

      if ((faceIndexSize = MEDmeshnEntity(fid,meshname,MED_NO_DT,MED_NO_IT,
              MED_CELL,MED_POLYHEDRON,MED_INDEX_NODE,MED_NODAL,
              &coordinatechangement,
              &geotransformation)) < 0) {
        MESSAGE("ERROR : read number of polyedron ...");
        return -1;
      }
      ISCRUTE(faceIndexSize);

      /* how many nodes for the polyhedron connectivity ? */
      if ((connectivitysize = MEDmeshnEntity(fid,meshname,MED_NO_DT,MED_NO_IT,
               MED_CELL,MED_POLYHEDRON,MED_CONNECTIVITY,MED_NODAL,
               &coordinatechangement,
               &geotransformation)) < 0) {
        MESSAGE("ERROR : read connevity size ...");
        return -1;
        }
      ISCRUTE(connectivitysize);

      /* read mesh nodes coordinates */
      if ((coordinates = (med_float*) malloc(sizeof(med_float)*nnodes*spacedim)) == NULL) {
        MESSAGE("ERROR : memory allocation ...");
        return -1;
      }

      if (MEDmeshNodeCoordinateRd(fid, meshname, MED_NO_DT, MED_NO_IT, MED_FULL_INTERLACE,
                coordinates) < 0) {
        MESSAGE("ERROR : nodes coordinates ...");
        return -1;
      }
      for (i=0;i<nnodes*spacedim;i++)
        printf("%f - ",*(coordinates+i));
      printf("\n");

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

      if (MEDmeshPolyhedronRd(fid,meshname,MED_NO_DT,MED_NO_IT,MED_CELL,MED_NODAL,
                              index,faceindex,connectivity) < 0) {
        MESSAGE("ERROR : read polygon connectivity ...");
        return -1;
      }

      for (i=0;i<npoly;i++)
        {
        printf(">> MED_POLYHEDRON "IFORMAT" : \n",i+1);
        printf("---- Face Index         ----- : [ ");
        ind1 = *(index+i)-1;
        ind2 = *(index+i+1)-1;
        for (k=ind1;k<ind2;k++)
          printf(IFORMAT" ",*(faceindex+k));
        printf(" ] \n");
        printf("---- Connectivity       ----- : [ ");
        for (k=ind1;k<ind2;k++)
          {
          jind1 = *(faceindex+k)-1;
          jind2 = *(faceindex+k+1)-1;
          for (j=jind1;j<jind2;j++)
            printf(IFORMAT" ",*(connectivity+j));
          printf(" \n");
          }
        printf(" ] \n");
        }

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

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

      /* memory deallocation */
      if (coordinates)
        free(coordinates);

      if (index)
        free(index);

      if (faceindex)
        free(faceindex);

      if (connectivity)
        free(connectivity);

      return 0;
    }