SurfArea.cpp File Reference

#include "moab/Core.hpp"
#include "moab/Range.hpp"
#include "moab/CartVect.hpp"
#include <iostream>

Include dependency graph for SurfArea.cpp:

Go to the source code of this file.

Functions
double	compute_area (std::vector< EntityHandle > &)
int	main (int argc, char **argv)
Variables
Interface *	mb

---

Function Documentation

double compute_area

(

std::vector< EntityHandle > &

entities

)

Definition at line 95 of file SurfArea.cpp.

References ErrorCode, moab::Core::get_connectivity(), moab::Core::get_coords(), length(), mb, and MB_SUCCESS.

Referenced by main().

{

    ErrorCode rval = MB_SUCCESS;
    double area    = 0.0;

    // loop thro' all the elements
    for( int i = 0; i < int( entities.size() ); i++ )
    {
        std::vector< EntityHandle > conn;
        EntityHandle handle = entities[i];

        // get the connectivity of this element
        rval = mb->get_connectivity( &handle, 1, conn );
        if( MB_SUCCESS != rval ) return -1.0;

        // break polygon into triangles and sum the area - Limitation: Convex polygon
        for( int j = 2; j <= int( conn.size() ); ++j )
        {

            EntityHandle vertices[3] = { conn[0], conn[j - 1], conn[j - 2] };
            CartVect coords[3];

            // get 3 coordinates forming the triangle
            rval = mb->get_coords( vertices, 3, coords[0].array() );
            if( MB_SUCCESS != rval ) return -1.0;

            CartVect edge0 = coords[1] - coords[0];
            CartVect edge1 = coords[2] - coords[0];

            // using MBCarVect overloaded operators and computing triangle area
            area += ( edge0 * edge1 ).length() / 2.0;
        }
    }
    // clear the entities, else old entities remain
    entities.clear();
    return area;
}

int main	(	int	argc,
		char **	argv
	)

Definition at line 22 of file SurfArea.cpp.

References moab::Range::begin(), compute_area(), moab::Range::end(), ErrorCode, moab::Core::get_entities_by_dimension(), moab::Core::get_entities_by_type_and_tag(), moab::Core::load_file(), mb, MB_SUCCESS, MB_TYPE_INTEGER, MBENTITYSET, moab::Core::tag_get_data(), and moab::Core::tag_get_handle().

{
    if( 1 == argc )
    {
        std::cout << "Usage: " << argv[0] << " <filename>" << std::endl;
        return 0;
    }

    // declare variables
    Tag gtag, idtag;
    ErrorCode rval;
    const char* tag_geom = "GEOM_DIMENSION";
    const char* tag_gid  = "GLOBAL_ID";
    Range sets;
    std::vector< EntityHandle > ents;

    // load a file
    mb   = new Core();
    rval = mb->load_file( argv[1] );
    if( MB_SUCCESS != rval ) return 1;

    // get the tag handle for the tags
    rval = mb->tag_get_handle( tag_geom, 1, MB_TYPE_INTEGER, gtag );
    if( MB_SUCCESS != rval ) return 1;
    rval = mb->tag_get_handle( tag_gid, 1, MB_TYPE_INTEGER, idtag );
    if( MB_SUCCESS != rval ) return 1;

    // get all the sets with GEOM_DIMESION tag
    rval = mb->get_entities_by_type_and_tag( 0, MBENTITYSET, &gtag, NULL, 1, sets );
    if( MB_SUCCESS != rval ) return 1;

    // iterate over each set, getting entities
    Range::iterator set_it;

    // loop thru all the geometric entity sets
    for( set_it = sets.begin(); set_it != sets.end(); ++set_it )
    {

        EntityHandle this_set = *set_it;

        // get the id for this set
        int set_id;
        rval = mb->tag_get_data( gtag, &this_set, 1, &set_id );
        if( MB_SUCCESS != rval ) return 1;

        // check if it is a surface entities (GEOM_DIMENSION 2) then compute area
        if( set_id == 2 )
        {

            // area of a surface
            double total_area = 0.0;

            // get the global id of this surface
            int gid = 0;
            rval    = mb->tag_get_data( idtag, &this_set, 1, &gid );
            if( MB_SUCCESS != rval ) return 1;

            // get all entities with dimension 2 in ents
            rval = mb->get_entities_by_dimension( this_set, 2, ents );
            if( MB_SUCCESS != rval ) return 1;

            // compute the area
            total_area = compute_area( ents );

            ents.clear();

            std::cout << "Total area of meshes in surface " << gid << " =  " << total_area << std::endl;
        }
    }
}

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Variable Documentation

Interface* mb

Definition at line 20 of file SurfArea.cpp.