measure.cpp

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/*
 * Copyright (c) 2005 Lawrence Livermore National Laboratory under
 * contract number B545069 with the University of Wisconsin - Madison.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer.
 * 2. Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the following disclaimer in the
 *    documentation and/or other materials provided with the distribution.
 *
 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
 * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
 * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
 * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
 * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
 * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
 * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 */

#include "moab/CartVect.hpp"
#include "measure.hpp"
using namespace moab;

inline static double tet_volume( const CartVect& v0, const CartVect& v1, const CartVect& v2, const CartVect& v3 )
{
    return 1. / 6. * ( ( ( v1 - v0 ) * ( v2 - v0 ) ) % ( v3 - v0 ) );
}

double edge_length( const double* start_vtx_coords, const double* end_vtx_coords )
{
    const CartVect* start = reinterpret_cast< const CartVect* >( start_vtx_coords );
    const CartVect* end   = reinterpret_cast< const CartVect* >( end_vtx_coords );
    return ( *start - *end ).length();
}

double measure( moab::EntityType type, int num_vertices, const double* vertex_coordinates )
{
    const CartVect* coords = reinterpret_cast< const CartVect* >( vertex_coordinates );
    switch( type )
    {
        case moab::MBEDGE:
            return ( coords[0] - coords[1] ).length();
        case moab::MBTRI:
            return 0.5 * ( ( coords[1] - coords[0] ) * ( coords[2] - coords[0] ) ).length();
        case moab::MBQUAD:
            num_vertices = 4;
            // fall through
        case moab::MBPOLYGON: {
            CartVect mid( 0, 0, 0 );
            for( int i = 0; i < num_vertices; ++i )
                mid += coords[i];
            mid /= num_vertices;

            double sum = 0.0;
            for( int i = 0; i < num_vertices; ++i )
            {
                int j = ( i + 1 ) % num_vertices;
                sum += ( ( mid - coords[i] ) * ( mid - coords[j] ) ).length();
            }
            return 0.5 * sum;
        }
        case moab::MBTET:
            return tet_volume( coords[0], coords[1], coords[2], coords[3] );
        case moab::MBPYRAMID:
            return tet_volume( coords[0], coords[1], coords[2], coords[4] ) +
                   tet_volume( coords[0], coords[2], coords[3], coords[4] );
        case moab::MBPRISM:
            return tet_volume( coords[0], coords[1], coords[2], coords[5] ) +
                   tet_volume( coords[3], coords[5], coords[4], coords[0] ) +
                   tet_volume( coords[1], coords[4], coords[5], coords[0] );
        case moab::MBHEX:
            return tet_volume( coords[0], coords[1], coords[3], coords[4] ) +
                   tet_volume( coords[7], coords[3], coords[6], coords[4] ) +
                   tet_volume( coords[4], coords[5], coords[1], coords[6] ) +
                   tet_volume( coords[1], coords[6], coords[3], coords[4] ) +
                   tet_volume( coords[2], coords[6], coords[3], coords[1] );
        default:
            return 0.0;
    }
}