QuadTriConv.cpp

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    1 /** @example QuadTriConv.cpp \n
    2  * \brief Merge vertices in 2d cell, if they are repeated \n
    3  * <b>To run</b>: QuadTriConv  input_file output_file \n
    4  *
    5  * In this example, a mesh that has vertices repeated due to south or north pole, for
    6  *  example in an rll mesh, need to be converted to triangles, preserving GLOBAL_ID tag
    7  */
    8  
    9 #include <iostream>
   10 #include <vector>
   11 //#include <string>
   12  
   13 // Include header for MOAB instance and tag conventions for
   14 #include "moab/Core.hpp"
   15 #include "MBTagConventions.hpp"
   16  
   17 using namespace moab;
   18 using namespace std;
   19  
   20 int main( int argc, char** argv )
   21 {
   22     // Get MOAB instance
   23     Interface* mb = new( std::nothrow ) Core;
   24     if( NULL == mb ) return 1;
   25  
   26     std::string filename, outfile;
   27     outfile = string( "out.h5m" );
   28     if( argc == 1 ) return 0;
   29     if( argc > 1 ) filename = string( argv[1] );
   30     if( argc > 2 ) outfile = string( argv[2] );
   31  
   32     // This file is in the mesh files directory
   33     ErrorCode rval = mb->load_file( filename.c_str() );MB_CHK_SET_ERR( rval, "Failed to read" );
   34  
   35     // get all cells of dimension 2;
   36     Range cells;
   37     rval = mb->get_entities_by_dimension( 0, 2, cells );MB_CHK_SET_ERR( rval, "Failed to get cells" );
   38  
   39     cout << " number of cells : " << cells.size() << "\n";
   40  
   41     Tag gid;  // global id tag
   42     rval = mb->tag_get_handle( "GLOBAL_ID", gid );MB_CHK_SET_ERR( rval, "Failed to get Global ID tag" );
   43  
   44     Range modifiedCells;  // will be deleted at the end; keep the gid
   45  
   46     for( Range::iterator cit = cells.begin(); cit != cells.end(); cit++ )
   47     {
   48         EntityHandle cell          = *cit;
   49         const EntityHandle* connec = NULL;
   50         int num_verts              = 0;
   51         rval                       = mb->get_connectivity( cell, connec, num_verts );MB_CHK_SET_ERR( rval, "Failed to get connectivity" );
   52  
   53         vector< EntityHandle > newConnec;
   54         newConnec.push_back( connec[0] );  // at least one vertex
   55         int index    = 0;
   56         int new_size = 1;
   57         while( index < num_verts - 2 )
   58         {
   59             int next_index = ( index + 1 );
   60             if( connec[next_index] != newConnec[new_size - 1] )
   61             {
   62                 newConnec.push_back( connec[next_index] );
   63                 new_size++;
   64             }
   65             index++;
   66         }
   67         // add the last one only if different from previous and first node
   68         if( ( connec[num_verts - 1] != connec[num_verts - 2] ) && ( connec[num_verts - 1] != connec[0] ) )
   69         {
   70             newConnec.push_back( connec[num_verts - 1] );
   71             new_size++;
   72         }
   73         if( new_size < num_verts )
   74         {
   75             // cout << "new cell from " << cell << " has only " << new_size << " vertices \n";
   76             modifiedCells.insert( cell );
   77             // create a new cell with type triangle, quad or polygon
   78             EntityType type = MBTRI;
   79             if( new_size == 3 )
   80                 type = MBTRI;
   81             else if( new_size == 4 )
   82                 type = MBQUAD;
   83             else if( new_size > 4 )
   84                 type = MBPOLYGON;
   85  
   86             // create new cell
   87             EntityHandle newCell;
   88             rval = mb->create_element( type, &newConnec[0], new_size, newCell );MB_CHK_SET_ERR( rval, "Failed to create new cell" );
   89             // set the old id to the new element
   90             int id;
   91             rval = mb->tag_get_data( gid, &cell, 1, &id );MB_CHK_SET_ERR( rval, "Failed to get global id" );
   92             rval = mb->tag_set_data( gid, &newCell, 1, &id );MB_CHK_SET_ERR( rval, "Failed to set global id on new cell" );
   93         }
   94     }
   95  
   96     mb->delete_entities( modifiedCells );
   97     // in case global ids are not set for vertices, set them, in order;
   98     // they are needed for migrating later on
   99     //
  100     Range verts;
  101     rval = mb->get_entities_by_dimension( 0, 0, verts );MB_CHK_SET_ERR( rval, "Failed to get vertices" );
  102  
  103     vector< int > gids;
  104     gids.resize( verts.size() );
  105     rval = mb->tag_get_data( gid, verts, &gids[0] );MB_CHK_SET_ERR( rval, "Failed to get gids on vertices" );
  106     if( gids[0] <= 0 )
  107     {
  108         // gids were never set, assign them
  109         for( size_t i = 1; i <= verts.size(); i++ )
  110             gids[i - 1] = (int)i;
  111         rval = mb->tag_set_data( gid, verts, &gids[0] );MB_CHK_SET_ERR( rval, "Failed to set gids on vertices" );
  112     }
  113     rval = mb->write_file( outfile.c_str() );MB_CHK_SET_ERR( rval, "Failed to write new file" );
  114  
  115     cout << " wrote file " << outfile << " with " << modifiedCells.size() << " modified cells\n";
  116  
  117     delete mb;
  118     return 0;
  119 }