TagIterateC.cpp

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/*
 * This program shows how to get a pointer to tag memory, allowing an application to work
 * directly with tag memory instead of calling through the api.
 */

#include "iMesh.h"
#include "iMesh_extensions.h"
#include <cstdio>
#include <cstring>

#define CHKERR( e, m )           \
    if( iBase_SUCCESS != ( e ) ) \
    {                            \
        printf( m );             \
        return 1;                \
    }

int main( int argc, char* argv[] )
{
    iMesh_Instance mesh;
    iBase_EntitySetHandle root_set;
    int err;
    const char* filename;
    iBase_EntityArrIterator iter;
    iBase_TagHandle tagh;
    int count, atend;
    double* tag_data;
    int num_regions;

    if( argc == 2 )
    {
        filename = argv[1];
    }
    else
    {
        printf( "Usage: %s <mesh_filename>\n", argv[0] );
        return 0;
    }

    /* initialize the Mesh */
    iMesh_newMesh( NULL, &mesh, &err, 0 );CHKERR( err, "Failed to create a mesh instance.\n" );
    iMesh_getRootSet( mesh, &root_set, &err );CHKERR( err, "Failed to return a root set.\n" );

    iMesh_load( mesh, root_set, filename, NULL, &err, strlen( filename ), 0 );

    /* get the number of regions in the mesh */
    iMesh_getNumOfType( mesh, root_set, iBase_REGION, &num_regions, &err );CHKERR( err, "Failed to get number of regions." );

    /* get an iterator to all regions in the model */
    iMesh_initEntArrIter( mesh, root_set, iBase_REGION, iMesh_ALL_TOPOLOGIES, num_regions, 0, &iter, &err );CHKERR( err, "Failed to create iterator over regions." );

    /* create a tag to put on the regions */
    iMesh_createTagWithOptions( mesh, "dumtag", "moab:TAG_STORAGE_TYPE=DENSE moab:TAG_DEFAULT_VALUE=0.0", 1,
                                iBase_DOUBLE, &tagh, &err, 6, 54 );CHKERR( err, "Failed to create a tag.\n" );

    atend = 0;

    while( !atend )
    {

        /* get a pointer to that tag data; this will allocate tag storage if it isn't allocated yet
         */
        iMesh_tagIterate( mesh, tagh, iter, &tag_data, &count, &err );CHKERR( err, "Failed to create a tag.\n" );

        /* step the iterator over count entities */
        iMesh_stepEntArrIter( mesh, iter, count, &atend, &err );CHKERR( err, "Failed to step iterator.\n" );

        /* operate on tag data, or store it for later */
    }

    iMesh_dtor( mesh, &err );CHKERR( err, "Failed to destroy iMesh instance.\n" );

    return 0;
}