# usecases/c/UsesCase_MEDmesh_13.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 13 : a 2D unstructured mesh with 12 nodes and 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";
      const med_int spacedim = 2;
      const med_int meshdim = 2;
      /*                                         12345678901234561234567890123456 */
      const char axisname[2*MED_SNAME_SIZE+1] = "x               y               ";
      const char unitname[2*MED_SNAME_SIZE+1] = "cm              cm              ";
      const med_float coordinates[2*12] = { 0.5,   0.,
                                            1.5,   0.,
                                            0.,    0.5,
                                            1.,    0.5,
                                            2.,    0.5,
                                            0.,    1.,
                                            1.,    1.,
                                            2.,    1.,
                                            0.5,   2.,
                                            1.5,   2. };
      const med_int nnodes = 12;
      const med_int indexsize = 3;
      const med_int index[3] = {1,7,13};
      /* connectivity : 2 hexagons */
      const med_int connectivity[12] = {1,4,7,9,6,3,
                                        2,5,8,10,7,4};
      int ret=-1;

      /* open MED file */
      fid = MEDfileOpen("UsesCase_MEDmesh_13.med",
                        MED_ACC_CREAT);
      if (fid < 0) {
        MESSAGE("ERROR : file creation ...");
        goto ERROR;
      }

      /* write a comment in the file */
      if (MEDfileCommentWr(fid,
                           "A 2D unstructured mesh : 12, 12 polygons") < 0) {
        MESSAGE("ERROR : write file description ...");
        goto ERROR;
      }

      /* mesh creation : a 2D unstructured mesh */
      if (MEDmeshCr(fid,
                    meshname,
                    spacedim,
                    meshdim,
                    MED_UNSTRUCTURED_MESH,
                    "A 2D mesh with 2 polygons",
                    "",
                    MED_SORT_DTIT,
                    MED_CARTESIAN,
                    axisname,
                    unitname) < 0) {
        MESSAGE("ERROR : mesh creation ...");
        goto ERROR;
      }

      /* nodes coordinates in a cartesian axis in full interlace mode
         (X1,Y1, X2,Y2, X3,Y3, ...) with no iteration and computation step
      */
      if (MEDmeshNodeCoordinateWr(fid,
                                  meshname,
                                  MED_NO_DT,
                                  MED_NO_IT,
                                  MED_UNDEF_DT,
                                  MED_FULL_INTERLACE,
                                  nnodes,
                                  coordinates) < 0) {
        MESSAGE("ERROR : nodes coordinates ...");
        goto ERROR;
      }

      /* cells connectiviy is defined in nodal mode */
      /* 2 polygons */
      if (MEDmeshPolygonWr(fid,
                           meshname,
                           MED_NO_DT,
                           MED_NO_IT,
                           MED_UNDEF_DT,
                           MED_CELL,
                           MED_NODAL,
                           indexsize,
                           index,
                           connectivity) < 0) {
        MESSAGE("ERROR : polygon connectivity ...");
        goto ERROR;
      }

      /* create family 0 : by default, all mesh entities family number is 0 */
      if (MEDfamilyCr(fid,
                      meshname,
                      MED_NO_NAME,
                      0,
                      0,
                      MED_NO_GROUP) < 0) {
        MESSAGE("ERROR : family 0 creation ...");
        goto ERROR;
      }

      ret=0;
     ERROR:

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

      return ret;
    }