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;
}