StructuredMeshSimple.cpp File Reference

#include "moab/Core.hpp"
#include "moab/ScdInterface.hpp"
#include "moab/ProgOptions.hpp"
#include "moab/CN.hpp"
#include <iostream>
#include <vector>

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Macros
#define	MYSTREAM(a)    if( !rank ) cout << a << endl

Functions
int	main (int argc, char **argv)

Macro Definition Documentation

MYSTREAM

#define MYSTREAM

(

a

)

if( !rank ) cout << a << endl

Examples

StructuredMeshSimple.cpp.

Function Documentation

main()

int main	(	int	argc,
		char **	argv
	)

Examples

StructuredMeshSimple.cpp.

Definition at line 39 of file StructuredMeshSimple.cpp.

{
    int N = 10, dim = 3;
 
#ifdef MOAB_HAVE_MPI
    MPI_Init( &argc, &argv );
#endif
 
    ProgOptions opts;
    opts.addOpt< int >( string( "dim,d" ), string( "Dimension of mesh (default=3)" ), &dim );
    opts.addOpt< int >( string( ",n" ), string( "Number of elements on a side (default=10)" ), &N );
    opts.parseCommandLine( argc, argv );
 
    // 0. Instantiate MOAB and get the structured mesh interface
    Interface* mb = new( std::nothrow ) Core;
    if( NULL == mb ) return 1;
    ScdInterface* scdiface;
    ErrorCode rval = mb->query_interface( scdiface );MB_CHK_ERR( rval );  // Get a ScdInterface object through moab instance
 
    // 1. Decide what the local parameters of the mesh will be, based on parallel/serial and rank.
#ifdef MOAB_HAVE_MPI
    int rank = 0, nprocs = 1;
    MPI_Comm_size( MPI_COMM_WORLD, &nprocs );
    MPI_Comm_rank( MPI_COMM_WORLD, &rank );
    int ilow = rank * N, ihigh = ilow + N;
#else
    int rank = 0;
    int ilow = 0, ihigh = N;
#endif
 
    // 2. Create a N^d structured mesh, which includes (N+1)^d vertices and N^d elements.
    ScdBox* box;
    rval = scdiface->construct_box(
        HomCoord( ilow, ( dim > 1 ? 0 : -1 ),
                  ( dim > 2 ? 0 : -1 ) ),  // Use in-line logical tests to handle dimensionality
        HomCoord( ihigh, ( dim > 1 ? N : -1 ), ( dim > 2 ? N : -1 ) ), NULL,
        0,  // NULL coords vector and 0 coords (don't specify coords for now)
        box );MB_CHK_ERR( rval );  // box is the structured box object providing the parametric
                         // structured mesh interface for this rectangle of elements
 
    // 3. Get the vertices and elements from moab and check their numbers against (N+1)^d and N^d,
    // resp.
    Range verts, elems;
    rval = mb->get_entities_by_dimension( 0, 0, verts );MB_CHK_ERR( rval );  // First '0' specifies "root set", or entire MOAB instance, second the
    // entity dimension being requested
    rval = mb->get_entities_by_dimension( 0, dim, elems );MB_CHK_ERR( rval );
 
#define MYSTREAM( a ) \
    if( !rank ) cout << a << endl
 
    if( pow( N, dim ) == (int)elems.size() && pow( N + 1, dim ) == (int)verts.size() )
    {  // Expected #e and #v are N^d and (N+1)^d, resp.
#ifdef MOAB_HAVE_MPI
        MYSTREAM( "Proc 0: " );
#endif
        MYSTREAM( "Created " << elems.size() << " " << CN::EntityTypeName( mb->type_from_handle( *elems.begin() ) )
                             << " elements and " << verts.size() << " vertices." << endl );
    }
    else
        cout << "Created the wrong number of vertices or hexes!" << endl;
 
    // 4. Loop over elements in 3 nested loops over i, j, k; for each (i,j,k):
    vector< double > coords( 3 * pow( N + 1, dim ) );
    vector< EntityHandle > connect;
    for( int k = 0; k < ( dim > 2 ? N : 1 ); k++ )
    {
        for( int j = 0; j < ( dim > 1 ? N : 1 ); j++ )
        {
            for( int i = 0; i < N - 1; i++ )
            {
                // 4a. Get the element corresponding to (i,j,k)
                EntityHandle ehandle = box->get_element( i, j, k );
                if( 0 == ehandle ) return MB_FAILURE;
                // 4b. Get the connectivity of the element
                rval = mb->get_connectivity( &ehandle, 1, connect );MB_CHK_ERR( rval );  // Get the connectivity, in canonical order
                // 4c. Get the coordinates of the vertices comprising that element
                rval = mb->get_coords( &connect[0], connect.size(), &coords[0] );MB_CHK_ERR( rval );  // Get the coordinates of those vertices
            }
        }
    }
 
    // 5. Release the structured mesh interface and destroy the MOAB instance
    mb->release_interface( scdiface );  // Tell MOAB we're done with the ScdInterface
 
#ifdef MOAB_HAVE_MPI
    MPI_Finalize();
#endif
 
    return 0;
}

References ProgOptions::addOpt(), moab::Range::begin(), moab::ScdInterface::construct_box(), dim, moab::CN::EntityTypeName(), ErrorCode, moab::Core::get_connectivity(), moab::Core::get_coords(), moab::ScdBox::get_element(), moab::Core::get_entities_by_dimension(), mb, MB_CHK_ERR, MYSTREAM, ProgOptions::parseCommandLine(), moab::Interface::query_interface(), moab::Interface::release_interface(), moab::Range::size(), and moab::Core::type_from_handle().