MsqMeshEntity.cpp

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/* *****************************************************************
    MESQUITE -- The Mesh Quality Improvement Toolkit

    Copyright 2004 Sandia Corporation and Argonne National
    Laboratory.  Under the terms of Contract DE-AC04-94AL85000
    with Sandia Corporation, the U.S. Government retains certain
    rights in this software.

    This library is free software; you can redistribute it and/or
    modify it under the terms of the GNU Lesser General Public
    License as published by the Free Software Foundation; either
    version 2.1 of the License, or (at your option) any later version.

    This library is distributed in the hope that it will be useful,
    but WITHOUT ANY WARRANTY; without even the implied warranty of
    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
    Lesser General Public License for more details.

    You should have received a copy of the GNU Lesser General Public License
    (lgpl.txt) along with this library; if not, write to the Free Software
    Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA

    [email protected], [email protected], [email protected],
    [email protected], [email protected], [email protected]

  ***************************************************************** */
//
// ORIG-DATE: 16-May-02 at 10:26:21
//  LAST-MOD: 18-Jun-04 at 11:36:07 by Thomas Leurent
//
/*! \file MsqMeshEntity.cpp

\brief All elements in Mesquite are of type MsqMeshEntity. Their associated
functionality is implemented in this file.

    \author Thomas Leurent
    \author Michael Brewer
    \author Darryl Melander
    \date 2002-05-16
 */

#include "Mesquite.hpp"
#include "MsqMeshEntity.hpp"
#include "MsqVertex.hpp"
#include "PatchData.hpp"

#include <vector>
#include <ostream>
using std::endl;
using std::ostream;
using std::vector;

namespace MBMesquite
{

//! Gets the indices of the vertices of this element.
//! The indices are only valid in the PatchData from which
//! this element was retrieved.
//! The order of the vertices is the canonical order for this
//! element's type.
void MsqMeshEntity::get_vertex_indices( std::vector< std::size_t >& vertices ) const
{
    vertices.resize( vertex_count() );
    std::copy( vertexIndices, vertexIndices + vertex_count(), vertices.begin() );
}

//! Gets the indices of the vertices of this element.
//! The indices are only valid in the PatchData from which
//! this element was retrieved.
//! The order of the vertices is the canonical order for this
//! element's type.
//! The indices are placed appended to the end of the list.
//! The list is not cleared before appending this entity's vertices.
void MsqMeshEntity::append_vertex_indices( std::vector< std::size_t >& vertex_list ) const
{
    vertex_list.insert( vertex_list.end(), vertexIndices, vertexIndices + vertex_count() );
}

void MsqMeshEntity::get_node_indices( std::vector< std::size_t >& indices ) const
{
    indices.resize( node_count() );
    std::copy( vertexIndices, vertexIndices + node_count(), indices.begin() );
}

void MsqMeshEntity::append_node_indices( std::vector< std::size_t >& indices ) const
{
    indices.insert( indices.end(), vertexIndices, vertexIndices + node_count() );
}

/*! The centroid of an element containing n vertices with equal masses is located at
  \f[ \b{x} = \frac{ \sum_{i=1}^{n} \b{x}_i }{ n }  \f]
  where \f$ \b{x}_i  ,\, i=1,...,n\f$ are the vertices coordinates.
*/
void MsqMeshEntity::get_centroid( Vector3D& centroid, const PatchData& pd, MsqError& err ) const
{
    centroid               = 0.0;
    const MsqVertex* vtces = pd.get_vertex_array( err );MSQ_ERRRTN( err );
    size_t nve = vertex_count();
    for( size_t i = 0; i < nve; ++i )
        centroid += vtces[vertexIndices[i]];
    centroid /= nve;
}

static inline double corner_volume( const Vector3D& v0, const Vector3D& v1, const Vector3D& v2, const Vector3D& v3 )
{
    return ( v1 - v0 ) * ( v2 - v0 ) % ( v3 - v0 );
}

/*!
  \brief Computes the area of the given element.  Returned value is
  always non-negative.  If the entity passed is not a two-dimensional
  element, an error is set.*/
double MsqMeshEntity::compute_unsigned_area( PatchData& pd, MsqError& err )
{
    const MsqVertex* verts = pd.get_vertex_array( err );
    MSQ_ERRZERO( err );
    double tem = 0.0;
    switch( mType )
    {

        case TRIANGLE:
            tem = ( ( verts[vertexIndices[1]] - verts[vertexIndices[0]] ) *
                    ( verts[vertexIndices[2]] - verts[vertexIndices[0]] ) )
                      .length();
            return 0.5 * tem;

        case QUADRILATERAL:
            tem = ( ( verts[vertexIndices[1]] - verts[vertexIndices[0]] ) *
                    ( verts[vertexIndices[3]] - verts[vertexIndices[0]] ) )
                      .length();
            tem += ( ( verts[vertexIndices[3]] - verts[vertexIndices[2]] ) *
                     ( verts[vertexIndices[1]] - verts[vertexIndices[2]] ) )
                       .length();
            return ( tem / 2.0 );

        case POLYGON:
            // assume convex
            for( unsigned i = 1; i < numVertexIndices - 1; ++i )
                tem += ( ( verts[vertexIndices[i]] - verts[vertexIndices[0]] ) *
                         ( verts[vertexIndices[i + 1]] - verts[vertexIndices[0]] ) )
                           .length();
            return 0.5 * tem;

        case TETRAHEDRON:
            return 1.0 / 6.0 *
                   fabs( corner_volume( verts[vertexIndices[0]], verts[vertexIndices[1]], verts[vertexIndices[2]],
                                        verts[vertexIndices[3]] ) );

        case PYRAMID: {
            Vector3D m =
                verts[vertexIndices[0]] + verts[vertexIndices[1]] + verts[vertexIndices[2]] + verts[vertexIndices[3]];
            Vector3D t1 = verts[vertexIndices[0]] - verts[vertexIndices[2]];
            Vector3D t2 = verts[vertexIndices[1]] - verts[vertexIndices[3]];
            tem         = ( ( t1 + t2 ) * ( t1 - t2 ) ) % ( verts[vertexIndices[4]] - 0.25 * m );
            return ( 1.0 / 12.0 ) * fabs( tem );
        }

        case PRISM: {
            tem = corner_volume( verts[vertexIndices[0]], verts[vertexIndices[1]], verts[vertexIndices[2]],
                                 verts[vertexIndices[3]] );

            tem += corner_volume( verts[vertexIndices[1]], verts[vertexIndices[2]], verts[vertexIndices[3]],
                                  verts[vertexIndices[4]] );

            tem += corner_volume( verts[vertexIndices[2]], verts[vertexIndices[3]], verts[vertexIndices[4]],
                                  verts[vertexIndices[5]] );

            return 1.0 / 6.0 * fabs( tem );
        }

        case HEXAHEDRON: {

            tem = corner_volume( verts[vertexIndices[1]], verts[vertexIndices[2]], verts[vertexIndices[0]],
                                 verts[vertexIndices[5]] );

            tem += corner_volume( verts[vertexIndices[3]], verts[vertexIndices[0]], verts[vertexIndices[2]],
                                  verts[vertexIndices[7]] );

            tem += corner_volume( verts[vertexIndices[4]], verts[vertexIndices[7]], verts[vertexIndices[5]],
                                  verts[vertexIndices[0]] );

            tem += corner_volume( verts[vertexIndices[6]], verts[vertexIndices[5]], verts[vertexIndices[7]],
                                  verts[vertexIndices[2]] );

            tem += corner_volume( verts[vertexIndices[5]], verts[vertexIndices[2]], verts[vertexIndices[0]],
                                  verts[vertexIndices[7]] );

            return ( 1.0 / 6.0 ) * fabs( tem );
        }

        default:
            MSQ_SETERR( err )
            ( "Invalid type of element passed to compute unsigned area.", MsqError::UNSUPPORTED_ELEMENT );
            return 0;
    }
    return 0;
}

/*!
  \brief Computes the area of the given element.  Returned value can be
  negative.  If the entity passed is not a two-dimensional element, an
  error is set.*/
double MsqMeshEntity::compute_signed_area( PatchData& pd, MsqError& err )
{
    const MsqVertex* verts = pd.get_vertex_array( err );
    MSQ_ERRZERO( err );
    double tem  = 0.0;
    double tem2 = 0.0;
    Vector3D surface_normal;
    Vector3D cross_vec;
    size_t element_index = pd.get_element_index( this );

    switch( mType )
    {

        case TRIANGLE:
            cross_vec = ( ( verts[vertexIndices[1]] - verts[vertexIndices[0]] ) *
                          ( verts[vertexIndices[2]] - verts[vertexIndices[0]] ) );
            pd.get_domain_normal_at_element( element_index, surface_normal, err );
            MSQ_ERRZERO( err );
            tem = ( cross_vec.length() / 2.0 );
            // if normals do not point in same general direction, negate area
            if( cross_vec % surface_normal < 0 )
            {
                tem *= -1;
            }

            return tem;

        case QUADRILATERAL:
            cross_vec = ( ( verts[vertexIndices[1]] - verts[vertexIndices[0]] ) *
                          ( verts[vertexIndices[3]] - verts[vertexIndices[0]] ) );
            pd.get_domain_normal_at_element( element_index, surface_normal, err );
            MSQ_ERRZERO( err );
            tem = ( cross_vec.length() / 2.0 );
            // if normals do not point in same general direction, negate area
            if( cross_vec % surface_normal < 0 )
            {
                tem *= -1;
            }
            cross_vec = ( ( verts[vertexIndices[3]] - verts[vertexIndices[2]] ) *
                          ( verts[vertexIndices[1]] - verts[vertexIndices[2]] ) );
            tem2      = ( cross_vec.length() / 2.0 );
            // if normals do not point in same general direction, negate area
            if( cross_vec % surface_normal < 0 )
            {
                tem2 *= -1;
                // test to make sure surface normal existed
                // if(surface_normal.length_squared()<.5){
                // err.set_msg("compute_signed_area called without surface_normal available.");
                //}
            }
            return ( tem + tem2 );

        default:
            MSQ_SETERR( err )
            ( "Invalid type of element passed to compute unsigned area.", MsqError::UNSUPPORTED_ELEMENT );
            return 0;
    };
    return 0.0;
}

/*!Appends the indices (in the vertex array) of the vertices to connected
  to vertex_array[vertex_index] to the end of the vector vert_indices.
  The connected vertices are right-hand ordered as defined by the
  entity.

*/
void MsqMeshEntity::get_connected_vertices( std::size_t vertex_index,
                                            std::vector< std::size_t >& vert_indices,
                                            MsqError& err )
{
    // index is set to the index in the vertexIndices corresponding
    // to vertex_index
    int index;
    for( index = vertex_count() - 1; index >= 0; --index )
        if( vertexIndices[index] == vertex_index ) break;
    if( index < 0 )
    {
        MSQ_SETERR( err )( "Invalid vertex index.", MsqError::INVALID_ARG );
        return;
    }

    unsigned n;
    const unsigned* indices = TopologyInfo::adjacent_vertices( mType, index, n );
    if( !indices ) MSQ_SETERR( err )( "Element type not available", MsqError::INVALID_ARG );
    for( unsigned i = 0; i < n; ++i )
        vert_indices.push_back( vertexIndices[indices[i]] );
}

/*! Gives the normal at the surface point corner_pt ... but if not available,
    gives the normalized cross product of corner_vec1 and corner_vec2.
  */
/*
void MsqMeshEntity::compute_corner_normal(size_t corner,
                                          Vector3D &normal,
                                          PatchData &pd,
                                          MsqError &err)
{
  if ( get_element_type()==TRIANGLE || get_element_type()==QUADRILATERAL )
  {
      // There are two cases where we cannot get a normal from the
      // geometry that are not errors:
      // 1) There is no domain set
      // 2) The vertex is at a degenerate point on the geometry (e.g.
      //     tip of a cone.)

    bool have_normal = false;

      // Get normal from domain
    if (pd.domain_set())
    {
      size_t index = pd.get_element_index(this);
      pd.get_domain_normal_at_corner( index, corner, normal, err );MSQ_ERRRTN(err);

      double length = normal.length();
      if (length > DBL_EPSILON)
      {
        have_normal = true;
        normal /= length;
      }
    }

      // If failed to get normal from domain, calculate
      // from adjacent vertices.
    if ( !have_normal )
    {
      const int num_corner = this->vertex_count();
      const int prev_corner = (corner + num_corner - 1) % num_corner;
      const int next_corner = (corner + 1 ) % num_corner;
      const size_t this_idx = vertexIndices[corner];
      const size_t prev_idx = vertexIndices[prev_corner];
      const size_t next_idx = vertexIndices[next_corner];
      normal = (pd.vertex_by_index(next_idx) - pd.vertex_by_index(this_idx))
             * (pd.vertex_by_index(prev_idx) - pd.vertex_by_index(this_idx));
      normal.normalize();
    }
  }
  else
    MSQ_SETERR(err)("Should only be used for faces (tri, quads, ...).",
                    MsqError::INVALID_ARG);
}
*/

void MsqMeshEntity::compute_corner_normals( Vector3D normals[], PatchData& pd, MsqError& err )
{
    EntityTopology type = get_element_type();
    if( type != TRIANGLE && type != QUADRILATERAL && type != POLYGON )
    {
        MSQ_SETERR( err )
        ( "Should only be used for faces (tri, quads, ...).", MsqError::INVALID_ARG );
        return;
    }

    // There are two cases where we cannot get a normal from the
    // geometry that are not errors:
    // 1) There is no domain set
    // 2) The vertex is at a degenerate point on the geometry (e.g.
    //     tip of a cone.)

    // Get normal from domain
    if( pd.domain_set() )
    {
        size_t index = pd.get_element_index( this );
        pd.get_domain_normals_at_corners( index, normals, err );MSQ_ERRRTN( err );
    }

    // Check if normals are valid (none are valid if !pd.domain_set())
    const unsigned count = vertex_count();
    for( unsigned i = 0; i < count; ++i )
    {
        // If got valid normal from domain,
        // make it a unit vector and continue.
        if( pd.domain_set() )
        {
            double length = normals[i].length();
            if( length > DBL_EPSILON )
            {
                normals[i] /= length;
                continue;
            }
        }

        const size_t prev_idx = vertexIndices[( i + count - 1 ) % count];
        const size_t this_idx = vertexIndices[i];
        const size_t next_idx = vertexIndices[( i + 1 ) % count];

        // Calculate normal using edges adjacent to corner
        normals[i] = ( pd.vertex_by_index( next_idx ) - pd.vertex_by_index( this_idx ) ) *
                     ( pd.vertex_by_index( prev_idx ) - pd.vertex_by_index( this_idx ) );
        normals[i].normalize();
    }
}

ostream& operator<<( ostream& stream, const MsqMeshEntity& entity )
{
    size_t num_vert = entity.vertex_count();
    stream << "MsqMeshEntity " << &entity << " with vertices ";
    for( size_t i = 0; i < num_vert; ++i )
        stream << entity.vertexIndices[i] << " ";
    stream << endl;
    return stream;
}

/*! Get a array of indices that specifies for the given vertex
  the correct matrix map.  This is used by the I_DFT point
  relaxation methods in the laplacian smoothers.

*/
size_t MsqMeshEntity::get_local_matrix_map_about_vertex( PatchData& pd,
                                                         MsqVertex* vert,
                                                         size_t local_map_size,
                                                         int* local_map,
                                                         MsqError& err ) const
{
    // i iterates through elem's vertices
    int i = 0;
    // index is set to the index in the vertexIndices corresponding
    // to vertex_index
    int index                     = -1;
    int return_val                = 0;
    const MsqVertex* vertex_array = pd.get_vertex_array( err );
    if( err ) return return_val;

    switch( mType )
    {
        case TRIANGLE:
            MSQ_SETERR( err )
            ( "Requested function not yet supported for Triangles.", MsqError::NOT_IMPLEMENTED );

            break;

        case QUADRILATERAL:
            MSQ_SETERR( err )
            ( "Requested function not yet supported for Quadrilaterals.", MsqError::NOT_IMPLEMENTED );

            break;

        case TETRAHEDRON:
            if( local_map_size < 4 )
            {
                MSQ_SETERR( err )
                ( "Array of incorrect length sent to function.", MsqError::INVALID_ARG );
                return return_val;
            }
            return_val = 4;
            while( i < 4 )
            {
                if( &vertex_array[vertexIndices[i]] == vert )
                {
                    index = i;
                    break;
                }
                ++i;
            }
            switch( index )
            {
                case( 0 ):
                    local_map[0] = 0;
                    local_map[1] = 1;
                    local_map[2] = 2;
                    local_map[3] = 3;
                    break;
                case( 1 ):
                    local_map[0] = 1;
                    local_map[1] = 0;
                    local_map[2] = 3;
                    local_map[3] = 2;
                    break;
                case( 2 ):
                    local_map[0] = 2;
                    local_map[1] = 3;
                    local_map[2] = 0;
                    local_map[3] = 1;
                    break;
                case( 3 ):
                    local_map[0] = 3;
                    local_map[1] = 2;
                    local_map[2] = 1;
                    local_map[3] = 0;
                    break;
                default:
                    local_map[0] = -1;
                    local_map[1] = -1;
                    local_map[2] = -1;
                    local_map[3] = -1;
            };

            break;

        case HEXAHEDRON:
            MSQ_SETERR( err )
            ( "Requested function not yet supported for Hexahedrons.", MsqError::NOT_IMPLEMENTED );

            break;
        default:
            MSQ_SETERR( err )( "Element type not available", MsqError::UNSUPPORTED_ELEMENT );
            break;
    }
    return return_val;
}

void MsqMeshEntity::check_element_orientation( PatchData& pd, int& inverted, int& total, MsqError& err )
{
    NodeSet all = all_nodes( err );MSQ_ERRRTN( err );
    unsigned i;

    if( TopologyInfo::dimension( mType ) == 2 )
    {
        if( !pd.domain_set() )
        {
            total    = 0;
            inverted = 0;
            return;
        }

        const MappingFunction2D* mf = pd.get_mapping_function_2D( mType );
        if( !mf )
        {
            check_element_orientation_corners( pd, inverted, total, err );
            return;
        }

        NodeSet sample = mf->sample_points( all );
        total          = sample.num_nodes();
        inverted       = 0;

        if( sample.have_any_corner_node() )
        {
            for( i = 0; i < TopologyInfo::corners( mType ); ++i )
                if( sample.corner_node( i ) ) inverted += inverted_jacobian_2d( pd, all, Sample( 0, i ), err );
        }
        if( sample.have_any_mid_edge_node() )
        {
            for( i = 0; i < TopologyInfo::edges( mType ); ++i )
                if( sample.mid_edge_node( i ) ) inverted += inverted_jacobian_2d( pd, all, Sample( 1, i ), err );
        }
        if( sample.have_any_mid_face_node() ) inverted += inverted_jacobian_2d( pd, all, Sample( 2, 0 ), err );
    }
    else
    {
        const MappingFunction3D* mf = pd.get_mapping_function_3D( mType );
        if( !mf )
        {
            check_element_orientation_corners( pd, inverted, total, err );
            return;
        }

        NodeSet sample = mf->sample_points( all );
        total          = sample.num_nodes();
        inverted       = 0;

        if( sample.have_any_corner_node() )
        {
            for( i = 0; i < TopologyInfo::corners( mType ); ++i )
                if( sample.corner_node( i ) ) inverted += inverted_jacobian_3d( pd, all, Sample( 0, i ), err );
        }
        if( sample.have_any_mid_edge_node() )
        {
            for( i = 0; i < TopologyInfo::edges( mType ); ++i )
                if( sample.mid_edge_node( i ) ) inverted += inverted_jacobian_3d( pd, all, Sample( 1, i ), err );
        }
        if( sample.have_any_mid_face_node() )
        {
            for( i = 0; i < TopologyInfo::faces( mType ); ++i )
                if( sample.mid_face_node( i ) ) inverted += inverted_jacobian_3d( pd, all, Sample( 2, i ), err );
        }
        if( sample.have_any_mid_region_node() )
        {
            inverted += inverted_jacobian_3d( pd, all, Sample( 3, 0 ), err );
        }
    }
}

bool MsqMeshEntity::inverted_jacobian_3d( PatchData& pd, NodeSet nodes, Sample sample, MsqError& err )
{
    MsqMatrix< 3, 3 > J;
    MsqVector< 3 > junk[27];
    size_t junk2[27], junk3;
    assert( node_count() <= 27 );

    const MappingFunction3D* mf = pd.get_mapping_function_3D( mType );
    mf->jacobian( pd, pd.get_element_index( this ), nodes, sample, junk2, junk, junk3, J, err );
    MSQ_ERRZERO( err );
    // const double size_eps_sqr = sqr_Frobenius( J ) * DBL_EPSILON;
    const double d = det( J );
    double l1      = J.column( 0 ) % J.column( 0 );
    double l2      = J.column( 1 ) % J.column( 1 );
    double l3      = J.column( 2 ) % J.column( 2 );
    return d < 0 || d * d < DBL_EPSILON * DBL_EPSILON * l1 * l2 * l3;
}

bool MsqMeshEntity::inverted_jacobian_2d( PatchData& pd, NodeSet nodes, Sample sample, MsqError& err )
{
    MsqMatrix< 3, 2 > J;
    MsqVector< 2 > junk[9];
    size_t junk2[9], junk3;
    assert( node_count() <= 9 );

    const int idx               = pd.get_element_index( this );
    const MappingFunction2D* mf = pd.get_mapping_function_2D( mType );
    mf->jacobian( pd, idx, nodes, sample, junk2, junk, junk3, J, err );
    MSQ_ERRZERO( err );
    const MsqVector< 3 > cross = J.column( 0 ) * J.column( 1 );

    if( pd.domain_set() )
    {
        Vector3D norm;
        pd.get_domain_normal_at_sample( pd.get_element_index( this ), sample, norm, err );
        MSQ_ERRZERO( err );

        const MsqVector< 3 > N( &norm[0] );
        if( cross % N < 0.0 ) return true;
    }

    const double l1 = J.column( 0 ) % J.column( 0 );
    const double l2 = J.column( 1 ) % J.column( 1 );
    return cross % cross < DBL_EPSILON * DBL_EPSILON * l1 * l2;
}

NodeSet MsqMeshEntity::all_nodes( MsqError& err ) const
{
    bool mid_edge, mid_face, mid_vol;
    TopologyInfo::higher_order( mType, node_count(), mid_edge, mid_face, mid_vol, err );
    NodeSet result;
    result.set_all_corner_nodes( mType );
    if( mid_edge ) result.set_all_mid_edge_nodes( mType );
    if( mid_face ) result.set_all_mid_face_nodes( mType );
    if( mid_vol ) result.set_all_mid_region_nodes( mType );
    return result;
}

void MsqMeshEntity::check_element_orientation_corners( PatchData& pd, int& inverted, int& total, MsqError& err )
{
    int num_nodes = node_count();
    total = inverted = 0;

    if( node_count() > vertex_count() )
    {
        MSQ_SETERR( err )
        ( "Cannot perform inversion test for higher-order element"
          " without mapping function.",
          MsqError::UNSUPPORTED_ELEMENT );
        return;
    }

    const MsqVertex* vertices = pd.get_vertex_array( err );MSQ_ERRRTN( err );

    const Vector3D d_con( 1.0, 1.0, 1.0 );

    int i;
    Vector3D coord_vectors[3];
    Vector3D center_vector;

    switch( mType )
    {
        case TRIANGLE:

            if( !pd.domain_set() ) return;

            pd.get_domain_normal_at_element( this, coord_vectors[2], err );MSQ_ERRRTN( err );
            coord_vectors[2] = coord_vectors[2] / coord_vectors[2].length();  // Need unit normal
            center_vector    = vertices[vertexIndices[0]];
            coord_vectors[0] = vertices[vertexIndices[1]] - center_vector;
            coord_vectors[1] = vertices[vertexIndices[2]] - center_vector;
            total            = 1;
            inverted         = ( coord_vectors[2] % ( coord_vectors[0] * coord_vectors[1] ) <= 0.0 );
            break;

        case QUADRILATERAL:

            if( !pd.domain_set() ) return;

            pd.get_domain_normal_at_element( this, coord_vectors[2], err );MSQ_ERRRTN( err );
            coord_vectors[2] = coord_vectors[2] / coord_vectors[2].length();  // Need unit normal

            for( i = 0; i < 4; ++i )
            {
                center_vector    = vertices[vertexIndices[i]];
                coord_vectors[0] = vertices[vertexIndices[( i + 1 ) % 4]] - center_vector;
                coord_vectors[1] = vertices[vertexIndices[( i + 3 ) % 4]] - center_vector;
                ++total;
                inverted += ( coord_vectors[2] % ( coord_vectors[0] * coord_vectors[1] ) <= 0.0 );
            }
            break;

        case TETRAHEDRON:
            center_vector    = vertices[vertexIndices[0]];
            coord_vectors[0] = vertices[vertexIndices[1]] - center_vector;
            coord_vectors[1] = vertices[vertexIndices[2]] - center_vector;
            coord_vectors[2] = vertices[vertexIndices[3]] - center_vector;
            total            = 1;
            inverted         = ( coord_vectors[0] % ( coord_vectors[1] * coord_vectors[2] ) <= 0.0 );
            break;

        case POLYGON:

            if( !pd.domain_set() ) return;

            pd.get_domain_normal_at_element( this, coord_vectors[2], err );MSQ_ERRRTN( err );
            coord_vectors[2] = coord_vectors[2] / coord_vectors[2].length();  // Need unit normal

            for( i = 0; i < num_nodes; ++i )
            {
                center_vector    = vertices[vertexIndices[i]];
                coord_vectors[0] = vertices[vertexIndices[( i + 1 ) % num_nodes]] - center_vector;
                coord_vectors[1] = vertices[vertexIndices[( i + num_nodes - 1 ) % num_nodes]] - center_vector;
                ++total;
                inverted += ( coord_vectors[2] % ( coord_vectors[0] * coord_vectors[1] ) <= 0.0 );
            }
            break;

        default:  // generic code for 3D elements
        {
            size_t num_corners = corner_count();
            unsigned num_adj;
            const unsigned* adj_idx;
            for( unsigned j = 0; j < num_corners; ++j )
            {
                adj_idx = TopologyInfo::adjacent_vertices( mType, j, num_adj );
                if( 3 != num_adj )
                {
                    MSQ_SETERR( err )( "Unsupported element type.", MsqError::INVALID_ARG );
                    return;
                }

                center_vector    = vertices[vertexIndices[j]];
                coord_vectors[0] = vertices[vertexIndices[adj_idx[0]]] - center_vector;
                coord_vectors[1] = vertices[vertexIndices[adj_idx[1]]] - center_vector;
                coord_vectors[2] = vertices[vertexIndices[adj_idx[2]]] - center_vector;
                ++total;
                inverted += ( coord_vectors[0] % ( coord_vectors[1] * coord_vectors[2] ) <= 0.0 );
            }
            break;
        }
    }  // end switch over element type
}

}  // namespace MBMesquite