FBEngine.cpp

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#include <iostream>
#include <map>

#include "moab/FBEngine.hpp"
#include "moab/Interface.hpp"
#include "moab/GeomTopoTool.hpp"
#include "moab/GeomUtil.hpp"
#include "moab/OrientedBoxTreeTool.hpp"

#include <cstdlib>
#include <cstring>
#include <map>
#include <set>
#include <queue>
#include <algorithm>
#include <cassert>

#include "SmoothCurve.hpp"
#include "SmoothFace.hpp"

// this is just to replace MBI with moab interface, which is _mbImpl in this class
#define MBI _mbImpl
#define MBERRORR( rval, STR )                  \
    {                                          \
        if( MB_SUCCESS != ( rval ) )           \
        {                                      \
            std::cout << ( STR ) << std::endl; \
            return rval;                       \
        }                                      \
    }

namespace moab
{

// some tolerances for ray tracing and geometry intersections
// these are involved in ray tracing, at least

double tolerance         = 0.01;  // TODO: how is this used ????
double tolerance_segment = 0.01;  // for segments intersection, points collapse, area coordinates for triangles
// it should be a relative, not an absolute value
// as this splitting operation can create small edges, it should be relatively high
// or, it should be coordinated with the decimation errors
// we really just want to preserve the integrity of the mesh, we should avoid creating small edges
// or angles
const bool Debug_surf_eval = false;
bool debug_splits          = false;

// will compute intersection between a segment and slice of a plane
// output is the intersection point
bool intersect_segment_and_plane_slice( CartVect& from, CartVect& to, CartVect& p1, CartVect& p2, CartVect&,
                                        CartVect& normPlane, CartVect& intx_point, double& parPos )
{
    //
    // plane eq is normPlane % r + d = 0, or normPlane % r - normPlane%p1 = 0
    double dd      = -normPlane % p1;
    double valFrom = normPlane % from + dd;
    double valTo   = normPlane % to + dd;

    if( fabs( valFrom ) < tolerance_segment )
    {
        intx_point   = from;
        parPos       = 0.;
        double proj1 = ( intx_point - p1 ) % ( p2 - p1 );
        double proj2 = ( intx_point - p2 ) % ( p1 - p2 );
        if( proj1 <= -tolerance_segment || proj2 <= -tolerance_segment ) return false;
        if( debug_splits ) std::cout << "intx : " << intx_point << "\n";
        return true;
    }
    if( fabs( valTo ) < tolerance_segment )
    {
        intx_point   = to;
        parPos       = 1;
        double proj1 = ( intx_point - p1 ) % ( p2 - p1 );
        double proj2 = ( intx_point - p2 ) % ( p1 - p2 );
        if( proj1 <= -tolerance_segment || proj2 <= -tolerance_segment ) return false;
        if( debug_splits ) std::cout << "intx : " << intx_point << "\n";
        return true;
    }
    if( valFrom * valTo > 0 ) return false;  // no intersection, although it could be very close
    // else, it could intersect the plane; check for the slice too.
    parPos     = valFrom / ( valFrom - valTo );  // this is 0 for valFrom 0, 1 for valTo 0
    intx_point = from + ( to - from ) * parPos;
    // now check if the intx_point is indeed between p1 and p2 in the slice.
    double proj1 = ( intx_point - p1 ) % ( p2 - p1 );
    double proj2 = ( intx_point - p2 ) % ( p1 - p2 );
    if( proj1 <= -tolerance_segment || proj2 <= -tolerance_segment ) return false;

    if( debug_splits ) std::cout << "intx : " << intx_point << "\n";
    return true;
}

ErrorCode area_coordinates( Interface* mbi, EntityHandle tri, CartVect& pnt, double* area_coord,
                            EntityHandle& boundary_handle )
{

    int nnodes;
    const EntityHandle* conn3;
    ErrorCode rval = mbi->get_connectivity( tri, conn3, nnodes );
    MBERRORR( rval, "Failed to get connectivity" );
    assert( 3 == nnodes );
    CartVect P[3];
    rval = mbi->get_coords( conn3, nnodes, (double*)&P[0] );
    MBERRORR( rval, "Failed to get coordinates" );

    CartVect r0( P[0] - pnt );
    CartVect r1( P[1] - pnt );
    CartVect r2( P[2] - pnt );
    if( debug_splits )
    {
        std::cout << " nodes:" << conn3[0] << " " << conn3[1] << " " << conn3[2] << "\n";
        std::cout << " distances: " << r0.length() << " " << r1.length() << " " << r2.length() << "\n";
    }
    if( r0.length() < tolerance_segment )
    {
        area_coord[0]   = 1.;
        area_coord[1]   = 0.;
        area_coord[2]   = 0.;
        boundary_handle = conn3[0];
        return MB_SUCCESS;
    }
    if( r1.length() < tolerance_segment )
    {
        area_coord[0]   = 0.;
        area_coord[1]   = 1.;
        area_coord[2]   = 0.;
        boundary_handle = conn3[1];
        return MB_SUCCESS;
    }
    if( r2.length() < tolerance_segment )
    {
        area_coord[0]   = 0.;
        area_coord[1]   = 0.;
        area_coord[2]   = 1.;
        boundary_handle = conn3[2];
        return MB_SUCCESS;
    }

    CartVect v1( P[1] - P[0] );
    CartVect v2( P[2] - P[0] );

    double areaDouble = ( v1 * v2 ).length();  // the same for CartVect
    if( areaDouble < tolerance_segment * tolerance_segment ) { MBERRORR( MB_FAILURE, "area of triangle too small" ); }
    area_coord[0] = ( r1 * r2 ).length() / areaDouble;
    area_coord[1] = ( r2 * r0 ).length() / areaDouble;
    area_coord[2] = ( r0 * r1 ).length() / areaDouble;

    if( fabs( area_coord[0] + area_coord[1] + area_coord[2] - 1 ) > tolerance_segment )
    {
        MBERRORR( MB_FAILURE, "point outside triangle" );
    }
    // the tolerance is used here for area coordinates (0 to 1), and in other
    // parts it is used as an absolute distance; pretty inconsistent.
    bool side0 = ( area_coord[0] < tolerance_segment );
    bool side1 = ( area_coord[1] < tolerance_segment );
    bool side2 = ( area_coord[2] < tolerance_segment );
    if( !side0 && !side1 && !side2 ) return MB_SUCCESS;  // interior point
    // now, find out what boundary is in question
    // first, get all edges, in order
    std::vector< EntityHandle > edges;
    EntityHandle nn2[2];
    for( int i = 0; i < 3; i++ )
    {
        nn2[0] = conn3[( i + 1 ) % 3];
        nn2[1] = conn3[( i + 2 ) % 3];
        std::vector< EntityHandle > adjacent;
        rval = mbi->get_adjacencies( nn2, 2, 1, false, adjacent, Interface::INTERSECT );
        MBERRORR( rval, "Failed to get edges" );
        if( adjacent.size() != 1 ) MBERRORR( MB_FAILURE, "Failed to get adjacent edges" );
        // should be only one edge here
        edges.push_back( adjacent[0] );
    }

    if( side0 ) boundary_handle = edges[0];
    if( side1 ) boundary_handle = edges[1];
    if( side2 ) boundary_handle = edges[2];

    return MB_SUCCESS;
}

FBEngine::FBEngine( Interface* impl, GeomTopoTool* topoTool, const bool smooth )
    : _mbImpl( impl ), _my_geomTopoTool( topoTool ), _t_created( false ), _smooth( smooth ), _initialized( false ),
      _smthFace( NULL ), _smthCurve( NULL )
{
    if( !_my_geomTopoTool )
    {
        _my_geomTopoTool = new GeomTopoTool( _mbImpl );
        _t_created       = true;
    }
    // should this be part of the constructor or not?
    // Init();
}
FBEngine::~FBEngine()
{
    clean();
    _smooth = false;
}

void FBEngine::clean()
{
    if( _smooth )
    {
        _faces.clear();
        _edges.clear();
        int size1 = _my_gsets[1].size();
        int i     = 0;
        for( i = 0; i < size1; i++ )
            delete _smthCurve[i];
        delete[] _smthCurve;
        _smthCurve = NULL;
        size1      = _my_gsets[2].size();
        for( i = 0; i < size1; i++ )
            delete _smthFace[i];
        delete[] _smthFace;
        _smthFace = NULL;
        //_smooth = false;
    }

    for( int j = 0; j < 5; j++ )
        _my_gsets[j].clear();
    if( _t_created ) delete _my_geomTopoTool;
    _my_geomTopoTool = NULL;
    _t_created       = false;
}

ErrorCode FBEngine::Init()
{
    if( !_initialized )
    {
        if( !_my_geomTopoTool ) return MB_FAILURE;

        ErrorCode rval = _my_geomTopoTool->find_geomsets( _my_gsets );
        assert( rval == MB_SUCCESS );
        if( MB_SUCCESS != rval ) { return rval; }

        rval = split_quads();
        assert( rval == MB_SUCCESS );

        rval = _my_geomTopoTool->construct_obb_trees();
        assert( rval == MB_SUCCESS );

        if( _smooth ) rval = initializeSmoothing();
        assert( rval == MB_SUCCESS );

        _initialized = true;
    }
    return MB_SUCCESS;
}
ErrorCode FBEngine::initializeSmoothing()
{
    //
    /*ErrorCode rval = Init();
     MBERRORR(rval, "failed initialize");*/
    // first of all, we need to retrieve all the surfaces from the (root) set
    // in icesheet_test we use iGeom, but maybe that is a stretch
    // get directly the sets with geom dim 2, and from there create the SmoothFace
    Tag geom_tag;
    ErrorCode rval = MBI->tag_get_handle( GEOM_DIMENSION_TAG_NAME, 1, MB_TYPE_INTEGER, geom_tag );
    MBERRORR( rval, "can't get geom tag" );

    int numSurfaces = _my_gsets[2].size();
    // SmoothFace ** smthFace = new SmoothFace *[numSurfaces];
    _smthFace = new SmoothFace*[numSurfaces];

    // there should also be a map from surfaces to evaluators
    // std::map<MBEntityHandle, SmoothFace*> mapSurfaces;

    int i = 0;
    Range::iterator it;
    for( it = _my_gsets[2].begin(); it != _my_gsets[2].end(); ++it, i++ )
    {
        EntityHandle face = *it;
        _smthFace[i] = new SmoothFace( MBI, face, _my_geomTopoTool );  // geom topo tool will be used for searching,
        // among other things; also for senses in edge sets...
        _faces[face] = _smthFace[i];
    }

    int numCurves = _my_gsets[1].size();  // csets.size();
    // SmoothCurve ** smthCurve = new SmoothCurve *[numCurves];
    _smthCurve = new SmoothCurve*[numCurves];
    // there should also be a map from surfaces to evaluators
    // std::map<MBEntityHandle, SmoothCurve*> mapCurves;

    i = 0;
    for( it = _my_gsets[1].begin(); it != _my_gsets[1].end(); ++it, i++ )
    {
        EntityHandle curve = *it;
        _smthCurve[i]      = new SmoothCurve( MBI, curve, _my_geomTopoTool );
        _edges[curve]      = _smthCurve[i];
    }

    for( i = 0; i < numSurfaces; i++ )
    {
        _smthFace[i]->init_gradient();                   // this will also retrieve the triangles in each surface
        _smthFace[i]->compute_tangents_for_each_edge();  // this one will consider all edges
                                                         // internal, so the
        // tangents are all in the direction of the edge; a little bit of waste, as we store
        // one tangent for each edge node , even though they are equal here...
        // no loops are considered
    }

    // this will be used to mark boundary edges, so for them the control points are computed earlier
    unsigned char value = 0;  // default value is "not used"=0 for the tag
    // unsigned char def_data_bit = 1;// valid by default
    // rval = mb->tag_create("valid", 1, MB_TAG_BIT, validTag, &def_data_bit);
    Tag markTag;
    rval = MBI->tag_get_handle( "MARKER", 1, MB_TYPE_BIT, markTag, MB_TAG_EXCL | MB_TAG_BIT,
                                &value );  // default value : 0 = not computed yet
    // each feature edge will need to have a way to retrieve at every moment the surfaces it belongs
    // to from edge sets, using the sense tag, we can get faces, and from each face, using the map,
    // we can get the SmoothFace (surface evaluator), that has everything, including the normals!!!
    assert( rval == MB_SUCCESS );

    // create the tag also for control points on the edges
    double defCtrlPoints[9] = { 0., 0., 0., 0., 0., 0., 0., 0., 0. };
    Tag edgeCtrlTag;
    rval = MBI->tag_get_handle( "CONTROLEDGE", 9, MB_TYPE_DOUBLE, edgeCtrlTag, MB_TAG_DENSE | MB_TAG_CREAT,
                                &defCtrlPoints );
    assert( rval == MB_SUCCESS );

    Tag facetCtrlTag;
    double defControls[18] = { 0. };
    rval = MBI->tag_get_handle( "CONTROLFACE", 18, MB_TYPE_DOUBLE, facetCtrlTag, MB_TAG_CREAT | MB_TAG_DENSE,
                                &defControls );
    assert( rval == MB_SUCCESS );

    Tag facetEdgeCtrlTag;
    double defControls2[27] = { 0. };  // corresponding to 9 control points on edges, in order
                                       // from edge 0, 1, 2 ( 1-2, 2-0, 0-1 )
    rval = MBI->tag_get_handle( "CONTROLEDGEFACE", 27, MB_TYPE_DOUBLE, facetEdgeCtrlTag, MB_TAG_CREAT | MB_TAG_DENSE,
                                &defControls2 );
    assert( rval == MB_SUCCESS );
    // if the
    double min_dot = -1.0;  // depends on _angle, but now we ignore it, for the time being
    for( i = 0; i < numCurves; i++ )
    {
        _smthCurve[i]->compute_tangents_for_each_edge();  // do we need surfaces now? or just the chains?
        // the computed edges will be marked accordingly; later one, only internal edges to surfaces
        // are left
        _smthCurve[i]->compute_control_points_on_boundary_edges( min_dot, _faces, edgeCtrlTag, markTag );
    }

    // when done with boundary edges, compute the control points on all edges in the surfaces

    for( i = 0; i < numSurfaces; i++ )
    {
        // also pass the tags for
        _smthFace[i]->compute_control_points_on_edges( min_dot, edgeCtrlTag, markTag );
    }

    // now we should be able to compute the control points for the facets

    for( i = 0; i < numSurfaces; i++ )
    {
        // also pass the tags for edge and facet control points
        _smthFace[i]->compute_internal_control_points_on_facets( min_dot, facetCtrlTag, facetEdgeCtrlTag );
    }
    // we will need to compute the tangents for all edges in the model
    // they will be needed for control points for each edge
    // the boundary edges and the feature edges are more complicated
    // the boundary edges need to consider their loops, but feature edges need to consider loops and
    // the normals on each connected surface

    // some control points
    if( Debug_surf_eval )
        for( i = 0; i < numSurfaces; i++ )
            _smthFace[i]->DumpModelControlPoints();

    return MB_SUCCESS;
}

// clean up the smooth tags data if created, so the files will be smaller
// if saved
// also, recompute the tags if topology is modified
void FBEngine::delete_smooth_tags()
{
    // get all tags from database that are created for smooth data, and
    // delete them; it will delete all data associated with them
    // first tags from faces, edges:
    std::vector< Tag > smoothTags;
    int size1 = (int)_my_gsets[2].size();

    for( int i = 0; i < size1; i++ )
    {
        // these 2 will append gradient tag and plane tag
        _smthFace[i]->append_smooth_tags( smoothTags );
    }
    // then , get other tags:
    // "TANGENTS", "MARKER", "CONTROLEDGE", "CONTROLFACE", "CONTROLEDGEFACE"
    Tag tag_handle;
    ErrorCode rval = _mbImpl->tag_get_handle( "TANGENTS", 6, MB_TYPE_DOUBLE, tag_handle );
    if( rval != MB_TAG_NOT_FOUND ) smoothTags.push_back( tag_handle );

    rval = _mbImpl->tag_get_handle( "MARKER", 1, MB_TYPE_BIT, tag_handle );
    if( rval != MB_TAG_NOT_FOUND ) smoothTags.push_back( tag_handle );

    rval = _mbImpl->tag_get_handle( "CONTROLEDGE", 9, MB_TYPE_DOUBLE, tag_handle );
    if( rval != MB_TAG_NOT_FOUND ) smoothTags.push_back( tag_handle );

    rval = _mbImpl->tag_get_handle( "CONTROLFACE", 18, MB_TYPE_DOUBLE, tag_handle );
    if( rval != MB_TAG_NOT_FOUND ) smoothTags.push_back( tag_handle );

    rval = _mbImpl->tag_get_handle( "CONTROLEDGEFACE", 27, MB_TYPE_DOUBLE, tag_handle );
    if( rval != MB_TAG_NOT_FOUND ) smoothTags.push_back( tag_handle );

    // a lot of tags, delete them
    for( unsigned int k = 0; k < smoothTags.size(); k++ )
    {
        // could be a lot of data
        _mbImpl->tag_delete( smoothTags[k] );
    }
}
/*
#define COPY_RANGE(r, vec) {                      \
    EntityHandle *tmp_ptr = reinterpret_cast<EntityHandle*>(vec);   \
    std::copy(r.begin(), r.end(), tmp_ptr);}
*/

/*static inline void
 ProcessError(const char* desc);*/

ErrorCode FBEngine::getRootSet( EntityHandle* root_set )
{
    *root_set = _my_geomTopoTool->get_root_model_set();
    return MB_SUCCESS;
}

ErrorCode FBEngine::getNumEntSets( EntityHandle set, int num_hops, int* all_sets )
{
    ErrorCode rval = MBI->num_contained_meshsets( set, all_sets, num_hops + 1 );
    return rval;
}

ErrorCode FBEngine::createEntSet( int isList, EntityHandle* pSet )
{
    ErrorCode rval;

    if( isList )
        rval = MBI->create_meshset( MESHSET_ORDERED, *pSet );
    else
        rval = MBI->create_meshset( MESHSET_SET, *pSet );

    return rval;
}

ErrorCode FBEngine::getEntities( EntityHandle set_handle, int entity_type, Range& gentities )
{
    int i;
    if( 0 > entity_type || 4 < entity_type ) { return MB_FAILURE; }
    else if( entity_type < 4 )
    {                                                            // 4 means all entities
        gentities = _my_geomTopoTool->geoRanges()[entity_type];  // all from root set!
    }
    else
    {
        gentities.clear();
        for( i = 0; i < 4; i++ )
        {
            gentities.merge( _my_geomTopoTool->geoRanges()[i] );
        }
    }
    Range sets;
    // see now if they are in the set passed as input or not
    ErrorCode rval = MBI->get_entities_by_type( set_handle, MBENTITYSET, sets );
    MBERRORR( rval, "can't get sets in the initial set" );
    gentities = intersect( gentities, sets );

    return MB_SUCCESS;
}

ErrorCode FBEngine::addEntArrToSet( const Range& entities, EntityHandle set )
{
    return MBI->add_entities( set, entities );
}

ErrorCode FBEngine::addEntSet( EntityHandle entity_set_to_add, EntityHandle entity_set_handle )
{
    return MBI->add_entities( entity_set_handle, &entity_set_to_add, 1 );
}

ErrorCode FBEngine::getNumOfType( EntityHandle set, int ent_type, int* pNum )
{
    if( 0 > ent_type || 4 < ent_type )
    {
        std::cout << "Invalid type\n";
        return MB_FAILURE;
    }
    // get sets of geom dimension tag from here, and intersect with the gentities from geo
    // ranges

    // get the geom dimensions sets in the set (AKA gentities)
    Range geom_sets;
    Tag geom_tag;
    ErrorCode rval =
        _mbImpl->tag_get_handle( GEOM_DIMENSION_TAG_NAME, 1, MB_TYPE_INTEGER, geom_tag, MB_TAG_SPARSE | MB_TAG_CREAT );
    MBERRORR( rval, "Failed to get geom tag." );
    rval = _mbImpl->get_entities_by_type_and_tag( set, MBENTITYSET, &geom_tag, NULL, 1, geom_sets, Interface::UNION );
    MBERRORR( rval, "Failed to get gentities from set" );

    if( ent_type == 4 )
    {
        *pNum = 0;
        for( int k = 0; k <= 3; k++ )
        {
            Range gEntsOfTypeK = intersect( geom_sets, _my_geomTopoTool->geoRanges()[k] );
            *pNum += (int)gEntsOfTypeK.size();
        }
    }
    else
    {
        Range gEntsOfType = intersect( geom_sets, _my_geomTopoTool->geoRanges()[ent_type] );
        *pNum             = (int)gEntsOfType.size();
    }
    // we do not really check if it is in the set or not;
    // _my_gsets[i].find(gent) != _my_gsets[i].end()
    return MB_SUCCESS;
}

ErrorCode FBEngine::getEntType( EntityHandle gent, int* type )
{
    for( int i = 0; i < 4; i++ )
    {
        if( _my_geomTopoTool->geoRanges()[i].find( gent ) != _my_geomTopoTool->geoRanges()[i].end() )
        {
            *type = i;
            return MB_SUCCESS;
        }
    }
    *type = -1;  // failure
    return MB_FAILURE;
}
ErrorCode FBEngine::getEntBoundBox( EntityHandle gent, double* min_x, double* min_y, double* min_z, double* max_x,
                                    double* max_y, double* max_z )
{
    ErrorCode rval;
    int type;
    rval = getEntType( gent, &type );
    MBERRORR( rval, "Failed to get entity type." );

    if( type == 0 )
    {
        rval = getVtxCoord( gent, min_x, min_y, min_z );
        MBERRORR( rval, "Failed to get vertex coordinates." );
        max_x = min_x;
        max_y = min_y;
        max_z = min_z;
    }
    else if( type == 1 )
    {
        MBERRORR( MB_FAILURE, "iGeom_getEntBoundBox is not supported for Edge entity type." );
    }
    else if( type == 2 || type == 3 )
    {

        EntityHandle root;
        CartVect center, axis[3];
        rval = _my_geomTopoTool->get_root( gent, root );
        MBERRORR( rval, "Failed to get tree root in iGeom_getEntBoundBox." );
        rval = _my_geomTopoTool->obb_tree()->box( root, center.array(), axis[0].array(), axis[1].array(),
                                                  axis[2].array() );
        MBERRORR( rval, "Failed to get closest point in iGeom_getEntBoundBox." );

        CartVect absv[3];
        for( int i = 0; i < 3; i++ )
        {
            absv[i] = CartVect( fabs( axis[i][0] ), fabs( axis[i][1] ), fabs( axis[i][2] ) );
        }
        CartVect min, max;
        min    = center - absv[0] - absv[1] - absv[2];
        max    = center + absv[0] + absv[1] + absv[2];
        *min_x = min[0];
        *min_y = min[1];
        *min_z = min[2];
        *max_x = max[0];
        *max_y = max[1];
        *max_z = max[2];
    }
    else
        return MB_FAILURE;

    return MB_SUCCESS;
}
ErrorCode FBEngine::getEntClosestPt( EntityHandle this_gent, double near_x, double near_y, double near_z, double* on_x,
                                     double* on_y, double* on_z )
{
    ErrorCode rval;
    int type;
    rval = getEntType( this_gent, &type );
    MBERRORR( rval, "Failed to get entity type." );

    if( type == 0 )
    {
        rval = getVtxCoord( this_gent, on_x, on_y, on_z );
        MBERRORR( rval, "Failed to get vertex coordinates." );
    }
    else if( _smooth && type == 1 )
    {
        *on_x                  = near_x;
        *on_y                  = near_y;
        *on_z                  = near_z;
        SmoothCurve* smthcurve = _edges[this_gent];
        // call the new method from smooth edge
        smthcurve->move_to_curve( *on_x, *on_y, *on_z );
    }
    else if( type == 2 || type == 3 )
    {
        double point[3] = { near_x, near_y, near_z };
        double point_out[3];
        EntityHandle root, facet_out;
        if( _smooth && 2 == type )
        {
            SmoothFace* smthFace = _faces[this_gent];
            *on_x                = near_x;
            *on_y                = near_y;
            *on_z                = near_z;
            smthFace->move_to_surface( *on_x, *on_y, *on_z );
        }
        else
        {
            rval = _my_geomTopoTool->get_root( this_gent, root );
            MBERRORR( rval, "Failed to get tree root in iGeom_getEntClosestPt." );
            rval = _my_geomTopoTool->obb_tree()->closest_to_location( point, root, point_out, facet_out );
            MBERRORR( rval, "Failed to get closest point in iGeom_getEntClosestPt." );

            *on_x = point_out[0];
            *on_y = point_out[1];
            *on_z = point_out[2];
        }
    }
    else
        return MB_TYPE_OUT_OF_RANGE;

    return MB_SUCCESS;
}

ErrorCode FBEngine::getVtxCoord( EntityHandle vertex_handle, double* x0, double* y0, double* z0 )
{
    int type;
    ErrorCode rval = getEntType( vertex_handle, &type );
    MBERRORR( rval, "Failed to get entity type in getVtxCoord." );

    if( type != 0 ) { MBERRORR( MB_FAILURE, "Entity is not a vertex type." ); }

    Range entities;
    rval = MBI->get_entities_by_type( vertex_handle, MBVERTEX, entities );
    MBERRORR( rval, "can't get nodes in vertex set." );

    if( entities.size() != 1 ) { MBERRORR( MB_FAILURE, "Vertex has multiple points." ); }
    double coords[3];
    EntityHandle node = entities[0];
    rval              = MBI->get_coords( &node, 1, coords );
    MBERRORR( rval, "can't get coordinates." );
    *x0 = coords[0];
    *y0 = coords[1];
    *z0 = coords[2];

    return MB_SUCCESS;
}

ErrorCode FBEngine::gsubtract( EntityHandle entity_set_1, EntityHandle entity_set_2, EntityHandle result_entity_set )
{
    /*result_entity_set = subtract(entity_set_1, entity_set_2);*/
    Range ents1, ents2;
    ErrorCode rval = MBI->get_entities_by_type( entity_set_1, MBENTITYSET, ents1 );
    MBERRORR( rval, "can't get entities from set 1." );

    rval = MBI->get_entities_by_type( entity_set_2, MBENTITYSET, ents2 );
    MBERRORR( rval, "can't get entities from set 2." );

    ents1 = subtract( ents1, ents2 );
    rval  = MBI->clear_meshset( &result_entity_set, 1 );
    MBERRORR( rval, "can't empty set." );

    rval = MBI->add_entities( result_entity_set, ents1 );
    MBERRORR( rval, "can't add result to set." );

    return rval;
}

ErrorCode FBEngine::getEntNrmlXYZ( EntityHandle entity_handle, double x, double y, double z, double* nrml_i,
                                   double* nrml_j, double* nrml_k )
{
    // just do for surface and volume
    int type;
    ErrorCode rval = getEntType( entity_handle, &type );
    MBERRORR( rval, "Failed to get entity type in iGeom_getEntNrmlXYZ." );

    if( type != 2 && type != 3 )
    {
        MBERRORR( MB_FAILURE, "Entities passed into gentityNormal must be face or volume." );
    }

    if( _smooth && 2 == type )
    {
        SmoothFace* smthFace = _faces[entity_handle];
        //*on_x = near_x; *on_y = near_y; *on_z = near_z;
        smthFace->normal_at( x, y, z, *nrml_i, *nrml_j, *nrml_k );
    }
    else
    {
        // get closest location and facet
        double point[3] = { x, y, z };
        double point_out[3];
        EntityHandle root, facet_out;
        _my_geomTopoTool->get_root( entity_handle, root );
        rval = _my_geomTopoTool->obb_tree()->closest_to_location( point, root, point_out, facet_out );
        MBERRORR( rval, "Failed to get closest location in iGeom_getEntNrmlXYZ." );

        // get facet normal
        const EntityHandle* conn;
        int len;
        CartVect coords[3], normal;
        rval = MBI->get_connectivity( facet_out, conn, len );
        MBERRORR( rval, "Failed to get triangle connectivity in iGeom_getEntNrmlXYZ." );
        if( len != 3 ) MBERRORR( MB_FAILURE, " not a triangle, error " );

        rval = MBI->get_coords( conn, len, coords[0].array() );
        MBERRORR( rval, "Failed to get triangle coordinates in iGeom_getEntNrmlXYZ." );

        coords[1] -= coords[0];
        coords[2] -= coords[0];
        normal = coords[1] * coords[2];
        normal.normalize();
        *nrml_i = normal[0];
        *nrml_j = normal[1];
        *nrml_k = normal[2];
    }
    return MB_SUCCESS;
}

ErrorCode FBEngine::getPntRayIntsct( double x, double y, double z, double dir_x, double dir_y, double dir_z,
                                     std::vector< EntityHandle >& intersect_entity_handles,
                                     /* int storage_order,*/
                                     std::vector< double >& intersect_coords, std::vector< double >& param_coords )
{
    // this is pretty cool
    // we will return only surfaces (gentities )
    //
    ErrorCode rval;

    unsigned int numfaces = _my_gsets[2].size();
    // do ray fire
    const double point[] = { x, y, z };
    const double dir[]   = { dir_x, dir_y, dir_z };
    CartVect P( point );
    CartVect V( dir );

    // std::vector<double> distances;
    std::vector< EntityHandle > facets;
    // std::vector<EntityHandle> sets;
    unsigned int i;
    for( i = 0; i < numfaces; i++ )
    {
        EntityHandle face = _my_gsets[2][i];
        EntityHandle rootForFace;
        rval = _my_geomTopoTool->get_root( face, rootForFace );
        MBERRORR( rval, "Failed to get root of face." );
        std::vector< double > distances_out;
        std::vector< EntityHandle > sets_out;
        std::vector< EntityHandle > facets_out;
        rval = _my_geomTopoTool->obb_tree()->ray_intersect_sets( distances_out, sets_out, facets_out, rootForFace,
                                                                 tolerance, point, dir );
        unsigned int j;
        for( j = 0; j < distances_out.size(); j++ )
            param_coords.push_back( distances_out[j] );
        for( j = 0; j < sets_out.size(); j++ )
            intersect_entity_handles.push_back( sets_out[j] );
        for( j = 0; j < facets_out.size(); j++ )
            facets.push_back( facets_out[j] );

        MBERRORR( rval, "Failed to get ray intersections." );
    }
    // facets.size == distances.size()!!
    for( i = 0; i < param_coords.size(); i++ )
    {
        CartVect intx = P + param_coords[i] * V;
        for( int j = 0; j < 3; j++ )
            intersect_coords.push_back( intx[j] );
    }
    if( _smooth )
    {
        // correct the intersection point and the distance for smooth surfaces
        for( i = 0; i < intersect_entity_handles.size(); i++ )
        {
            // EntityHandle geoSet = MBH_cast(sets[i]);
            SmoothFace* sFace = _faces[intersect_entity_handles[i]];
            // correct coordinates and distance from point
            /*moab::ErrorCode ray_intersection_correct(moab::EntityHandle facet, // (IN) the facet
             where the patch is defined moab::CartVect &pt, // (IN) shoot from moab::CartVect &ray,
             // (IN) ray direction moab::CartVect &eval_pt, // (INOUT) The intersection point double
             & distance, // (IN OUT) the new distance bool &outside);*/
            CartVect pos( &( intersect_coords[3 * i] ) );
            double dist  = param_coords[i];
            bool outside = false;
            rval         = sFace->ray_intersection_correct( facets[i], P, V, pos, dist, outside );
            MBERRORR( rval, "Failed to get better point on ray." );
            param_coords[i] = dist;

            for( int j = 0; j < 3; j++ )
                intersect_coords[3 * i + j] = pos[j];
        }
    }
    return MB_SUCCESS;
}

ErrorCode FBEngine::getAdjacentEntities( const EntityHandle from, const int to_dim, Range& adjs )
{
    int this_dim = -1;
    for( int i = 0; i < 4; i++ )
    {
        if( _my_geomTopoTool->geoRanges()[i].find( from ) != _my_geomTopoTool->geoRanges()[i].end() )
        {
            this_dim = i;
            break;
        }
    }

    // check target dimension
    if( -1 == this_dim )
    {
        // ProcessError(iBase_FAILURE, "Entity not a geometry entity.");
        return MB_FAILURE;
    }
    else if( 0 > to_dim || 3 < to_dim )
    {
        // ProcessError(iBase_FAILURE, "To dimension must be between 0 and 3.");
        return MB_FAILURE;
    }
    else if( to_dim == this_dim )
    {
        // ProcessError(iBase_FAILURE,
        //      "To dimension must be different from entity dimension.");
        return MB_FAILURE;
    }

    ErrorCode rval = MB_SUCCESS;
    adjs.clear();
    if( to_dim > this_dim )
    {
        int diffDim = to_dim - this_dim;
        rval        = MBI->get_parent_meshsets( from, adjs, diffDim );
        if( MB_SUCCESS != rval ) return rval;
        if( diffDim > 1 )
        {
            // subtract the parents that come with diffDim-1 hops
            Range extra;
            rval = MBI->get_parent_meshsets( from, extra, diffDim - 1 );
            if( MB_SUCCESS != rval ) return rval;
            adjs = subtract( adjs, extra );
        }
    }
    else
    {
        int diffDim = this_dim - to_dim;
        rval        = MBI->get_child_meshsets( from, adjs, diffDim );
        if( MB_SUCCESS != rval ) return rval;
        if( diffDim > 1 )
        {
            // subtract the children that come with diffDim-1 hops
            Range extra;
            rval = MBI->get_child_meshsets( from, extra, diffDim - 1 );
            if( MB_SUCCESS != rval ) return rval;
            adjs = subtract( adjs, extra );
        }
    }

    return rval;
}

// so far, this one is
// used only for __MKModelEntityGeo tag

ErrorCode FBEngine::createTag( const char* tag_name, int tag_size, int tag_type, Tag& tag_handle_out )
{
    // this is copied from iMesh_MOAB.cpp; different name to not have trouble
    // with it
    // also, we do not want to depend on iMesh.h...
    // iMesh is more complicated, because of the options passed

    DataType mb_data_type_table2[] = { MB_TYPE_OPAQUE, MB_TYPE_INTEGER, MB_TYPE_DOUBLE, MB_TYPE_HANDLE,
                                       MB_TYPE_HANDLE };
    moab::TagType storage          = MB_TAG_SPARSE;
    ErrorCode result;

    result =
        MBI->tag_get_handle( tag_name, tag_size, mb_data_type_table2[tag_type], tag_handle_out, storage | MB_TAG_EXCL );

    if( MB_SUCCESS != result )
    {
        std::string msg( "iMesh_createTag: " );
        if( MB_ALREADY_ALLOCATED == result )
        {
            msg += "Tag already exists with name: \"";
            msg += tag_name;
            std::cout << msg << "\n";
        }
        else
        {
            std::cout << "Failed to create tag with name: " << tag_name << "\n";
            return MB_FAILURE;
        }
    }

    // end copy
    return MB_SUCCESS;
}

ErrorCode FBEngine::getArrData( const EntityHandle* entity_handles, int entity_handles_size, Tag tag_handle,
                                void* tag_values_out )
{
    // responsibility of the user to have tag_values_out properly allocated
    // only some types of Tags are possible (double, int, etc)
    return MBI->tag_get_data( tag_handle, entity_handles, entity_handles_size, tag_values_out );
}

ErrorCode FBEngine::setArrData( const EntityHandle* entity_handles, int entity_handles_size, Tag tag_handle,
                                const void* tag_values )
{
    // responsibility of the user to have tag_values_out properly allocated
    // only some types of Tags are possible (double, int, etc)
    return MBI->tag_set_data( tag_handle, entity_handles, entity_handles_size, tag_values );
}

ErrorCode FBEngine::getEntAdj( EntityHandle handle, int type_requested, Range& adjEnts )
{
    return getAdjacentEntities( handle, type_requested, adjEnts );
}

ErrorCode FBEngine::getEgFcSense( EntityHandle mbedge, EntityHandle mbface, int& sense_out )
{

    // this one is important, for establishing the orientation of the edges in faces
    // use senses
    std::vector< EntityHandle > faces;
    std::vector< int > senses;  // 0 is forward and 1 is backward
    ErrorCode rval = _my_geomTopoTool->get_senses( mbedge, faces, senses );
    if( MB_SUCCESS != rval ) return rval;

    for( unsigned int i = 0; i < faces.size(); i++ )
    {
        if( faces[i] == mbface )
        {
            sense_out = senses[i];
            return MB_SUCCESS;
        }
    }
    return MB_FAILURE;
}
// we assume the measures array was allocated correctly
ErrorCode FBEngine::measure( const EntityHandle* moab_entities, int entities_size, double* measures )
{
    ErrorCode rval;
    for( int i = 0; i < entities_size; i++ )
    {
        measures[i] = 0.;

        int type;
        EntityHandle gset = moab_entities[i];
        rval              = getEntType( gset, &type );
        if( MB_SUCCESS != rval ) return rval;
        if( type == 1 )
        {  // edge: get all edges part of the edge set
            Range entities;
            rval = MBI->get_entities_by_type( gset, MBEDGE, entities );
            if( MB_SUCCESS != rval ) return rval;

            for( Range::iterator it = entities.begin(); it != entities.end(); ++it )
            {
                EntityHandle edge = *it;
                CartVect vv[2];
                const EntityHandle* conn2 = NULL;
                int num_nodes;
                rval = MBI->get_connectivity( edge, conn2, num_nodes );
                if( MB_SUCCESS != rval || num_nodes != 2 ) return MB_FAILURE;
                rval = MBI->get_coords( conn2, 2, (double*)&( vv[0][0] ) );
                if( MB_SUCCESS != rval ) return rval;

                vv[0] = vv[1] - vv[0];
                measures[i] += vv[0].length();
            }
        }
        if( type == 2 )
        {  // surface
            // get triangles in surface; TODO: quads!
            Range entities;
            rval = MBI->get_entities_by_type( gset, MBTRI, entities );
            if( MB_SUCCESS != rval ) return rval;

            for( Range::iterator it = entities.begin(); it != entities.end(); ++it )
            {
                EntityHandle tri = *it;
                CartVect vv[3];
                const EntityHandle* conn3 = NULL;
                int num_nodes;
                rval = MBI->get_connectivity( tri, conn3, num_nodes );
                if( MB_SUCCESS != rval || num_nodes != 3 ) return MB_FAILURE;
                rval = MBI->get_coords( conn3, 3, (double*)&( vv[0][0] ) );
                if( MB_SUCCESS != rval ) return rval;

                vv[1] = vv[1] - vv[0];
                vv[2] = vv[2] - vv[0];
                vv[0] = vv[1] * vv[2];
                measures[i] += vv[0].length() / 2;  // area of triangle
            }
        }
    }
    return MB_SUCCESS;
}

ErrorCode FBEngine::getEntNrmlSense( EntityHandle /*face*/, EntityHandle /*region*/, int& /*sense*/ )
{
    return MB_NOT_IMPLEMENTED;  // not implemented
}

ErrorCode FBEngine::getEgEvalXYZ( EntityHandle /*edge*/, double /*x*/, double /*y*/, double /*z*/, double& /*on_x*/,
                                  double& /*on_y*/, double& /*on_z*/, double& /*tngt_i*/, double& /*tngt_j*/,
                                  double& /*tngt_k*/, double& /*cvtr_i*/, double& /*cvtr_j*/, double& /*cvtr_k*/ )
{
    return MB_NOT_IMPLEMENTED;  // not implemented
}
ErrorCode FBEngine::getFcEvalXYZ( EntityHandle /*face*/, double /*x*/, double /*y*/, double /*z*/, double& /*on_x*/,
                                  double& /*on_y*/, double& /*on_z*/, double& /*nrml_i*/, double& /*nrml_j*/,
                                  double& /*nrml_k*/, double& /*cvtr1_i*/, double& /*cvtr1_j*/, double& /*cvtr1_k*/,
                                  double& /*cvtr2_i*/, double& /*cvtr2_j*/, double& /*cvtr2_k*/ )
{
    return MB_NOT_IMPLEMENTED;  // not implemented
}

ErrorCode FBEngine::getEgVtxSense( EntityHandle edge, EntityHandle vtx1, EntityHandle vtx2, int& sense )
{
    // need to decide first or second vertex
    // important for moab
    int type;

    EntityHandle v1, v2;
    ErrorCode rval = getEntType( vtx1, &type );
    if( MB_SUCCESS != rval || type != 0 ) return MB_FAILURE;
    // edge: get one vertex as part of the vertex set
    Range entities;
    rval = MBI->get_entities_by_type( vtx1, MBVERTEX, entities );
    if( MB_SUCCESS != rval ) return rval;
    if( entities.size() < 1 ) return MB_FAILURE;
    v1 = entities[0];  // the first vertex
    entities.clear();
    rval = getEntType( vtx2, &type );
    if( MB_SUCCESS != rval || type != 0 ) return MB_FAILURE;
    rval = MBI->get_entities_by_type( vtx2, MBVERTEX, entities );
    if( MB_SUCCESS != rval ) return rval;
    if( entities.size() < 1 ) return MB_FAILURE;
    v2 = entities[0];  // the first vertex
    entities.clear();
    // now get the edges, and get the first node and the last node in sequence of edges
    // the order is important...
    // these are ordered sets !!
    std::vector< EntityHandle > ents;
    rval = MBI->get_entities_by_type( edge, MBEDGE, ents );
    if( MB_SUCCESS != rval ) return rval;
    if( ents.size() < 1 ) return MB_FAILURE;

    const EntityHandle* conn = NULL;
    int len;
    EntityHandle startNode, endNode;
    rval = MBI->get_connectivity( ents[0], conn, len );
    if( MB_SUCCESS != rval ) return rval;
    startNode = conn[0];
    rval      = MBI->get_connectivity( ents[ents.size() - 1], conn, len );
    if( MB_SUCCESS != rval ) return rval;

    endNode = conn[1];
    sense   = 1;  //
    if( ( startNode == endNode ) && ( v1 == startNode ) )
    {
        sense = 0;  // periodic
    }
    if( ( startNode == v1 ) && ( endNode == v2 ) )
    {
        sense = 1;  // forward
    }
    if( ( startNode == v2 ) && ( endNode == v1 ) )
    {
        sense = -1;  // reverse
    }
    return MB_SUCCESS;
}

ErrorCode FBEngine::getEntURange( EntityHandle edge, double& u_min, double& u_max )
{
    SmoothCurve* smoothCurve = _edges[edge];  // this is a map
    // now, call smoothCurve methods
    smoothCurve->get_param_range( u_min, u_max );
    return MB_SUCCESS;
}

ErrorCode FBEngine::getEntUtoXYZ( EntityHandle edge, double u, double& x, double& y, double& z )
{
    SmoothCurve* smoothCurve = _edges[edge];  // this is a map
    // now, call smoothCurve methods
    smoothCurve->position_from_u( u, x, y, z );
    return MB_SUCCESS;
}

ErrorCode FBEngine::getEntTgntU( EntityHandle edge, double u, double& i, double& j, double& k )
{
    SmoothCurve* smoothCurve = _edges[edge];  // this is a map
    // now, call smoothCurve methods
    double tg[3];
    double x, y, z;
    smoothCurve->position_from_u( u, x, y, z, tg );
    i = tg[0];
    j = tg[1];
    k = tg[2];
    return MB_SUCCESS;
}
ErrorCode FBEngine::isEntAdj( EntityHandle entity1, EntityHandle entity2, bool& adjacent_out )
{
    int type1, type2;
    ErrorCode rval = getEntType( entity1, &type1 );
    if( MB_SUCCESS != rval ) return rval;
    rval = getEntType( entity2, &type2 );
    if( MB_SUCCESS != rval ) return rval;

    Range adjs;
    if( type1 < type2 )
    {
        rval = MBI->get_parent_meshsets( entity1, adjs, type2 - type1 );
        if( MB_SUCCESS != rval ) return rval;  // MBERRORR("Failed to get parent meshsets in iGeom_isEntAdj.");
    }
    else
    {
        // note: if they ave the same type, they will not be adjacent, in our definition
        rval = MBI->get_child_meshsets( entity1, adjs, type1 - type2 );
        if( MB_SUCCESS != rval ) return rval;  // MBERRORR("Failed to get child meshsets in iGeom_isEntAdj.");
    }

    // adjacent_out = adjs.find(entity2) != _my_gsets[type2].end();
    // hmmm, possible bug here; is this called?
    adjacent_out = adjs.find( entity2 ) != adjs.end();

    return MB_SUCCESS;
}

ErrorCode FBEngine::split_surface_with_direction( EntityHandle face, std::vector< double >& xyz, double* direction,
                                                  int closed, double min_dot, EntityHandle& oNewFace )
{

    // first of all, find all intersection points (piercing in the face along the direction)
    // assume it is robust; what if it is not sufficiently robust?
    // if the polyline is open, find the intersection with the boundary edges, of the
    // polyline extruded at ends

    ErrorCode rval;

    // then find the position
    int numIniPoints = (int)xyz.size() / 3;
    if( ( closed && numIniPoints < 3 ) || ( !closed && numIniPoints < 2 ) )
        MBERRORR( MB_FAILURE, "not enough polyline points " );
    EntityHandle rootForFace;

    rval = _my_geomTopoTool->get_root( face, rootForFace );
    MBERRORR( rval, "Failed to get root of face." );

    const double dir[] = { direction[0], direction[1], direction[2] };
    std::vector< EntityHandle > nodes;  // get the nodes closest to the ray traces of interest

    // these are nodes on the boundary of original face;
    // if the cutting line is not closed, the starting - ending vertices of the
    // polygonal line must come from this list

    std::vector< CartVect > b_pos;
    std::vector< EntityHandle > boundary_nodes;
    std::vector< EntityHandle > splittingNodes;
    Range boundary_mesh_edges;
    if( !closed )
    {
        rval = boundary_nodes_on_face( face, boundary_nodes );
        MBERRORR( rval, "Failed to get boundary nodes." );
        b_pos.resize( boundary_nodes.size() );
        rval = _mbImpl->get_coords( &( boundary_nodes[0] ), boundary_nodes.size(), (double*)( &b_pos[0][0] ) );
        MBERRORR( rval, "Failed to get coordinates for boundary nodes." );
        rval = boundary_mesh_edges_on_face( face, boundary_mesh_edges );
        MBERRORR( rval, "Failed to get mesh boundary edges for face." );
    }
    //
    int i = 0;
    CartVect dirct( direction );
    dirct.normalize();  // maybe an overkill?
    for( ; i < numIniPoints; i++ )
    {

        const double point[] = { xyz[3 * i], xyz[3 * i + 1], xyz[3 * i + 2] };  // or even point( &(xyz[3*i]) ); //
        CartVect p1( point );
        if( !closed && ( ( 0 == i ) || ( numIniPoints - 1 == i ) ) )
        {

            // find the intersection point between a plane and boundary mesh edges
            // this will be the closest point on the boundary of face
            /// the segment is the first or last segment in the polyline
            int i1 = i + 1;
            if( i == numIniPoints - 1 ) i1 = i - 1;  // previous point if the last
            // the direction is from point to point1
            const double point1[] = { xyz[3 * i1], xyz[3 * i1 + 1], xyz[3 * i1 + 2] };
            CartVect p2( point1 );
            CartVect normPlane = ( p2 - p1 ) * dirct;
            normPlane.normalize();
            //(roughly, from p1 to p2, perpendicular to dirct, in the "xy" plane
            // if the intx point is "outside" p1 - p2, skip if the intx point is closer to p2
            CartVect perpDir    = dirct * normPlane;
            Range::iterator ite = boundary_mesh_edges.begin();
            // do a linear search for the best intersection point position (on a boundary edge)
            if( debug_splits )
            {
                std::cout << " p1:" << p1 << "\n";
                std::cout << " p2:" << p2 << "\n";
                std::cout << " perpDir:" << perpDir << "\n";
                std::cout << " boundary edges size:" << boundary_mesh_edges.size() << "\n";
            }
            for( ; ite != boundary_mesh_edges.end(); ++ite )
            {
                EntityHandle candidateEdge = *ite;
                const EntityHandle* conn2;
                int nno;
                rval = _mbImpl->get_connectivity( candidateEdge, conn2, nno );
                MBERRORR( rval, "Failed to get conn for boundary edge" );
                CartVect pts[2];
                rval = _mbImpl->get_coords( conn2, 2, &( pts[0][0] ) );
                MBERRORR( rval, "Failed to get coords of nodes for boundary edge" );
                CartVect intx_point;
                double parPos;
                bool intersect =
                    intersect_segment_and_plane_slice( pts[0], pts[1], p1, p2, dirct, normPlane, intx_point, parPos );
                if( debug_splits )
                {
                    std::cout << "   Edge:" << _mbImpl->id_from_handle( candidateEdge ) << "\n";
                    std::cout << "   Node 1:" << _mbImpl->id_from_handle( conn2[0] ) << pts[0] << "\n";
                    std::cout << "   Node 2:" << _mbImpl->id_from_handle( conn2[1] ) << pts[1] << "\n";
                    std::cout << "    Intersect bool:" << intersect << "\n";
                }
                if( intersect )
                {
                    double proj1 = ( intx_point - p1 ) % perpDir;
                    double proj2 = ( intx_point - p2 ) % perpDir;
                    if( ( fabs( proj1 ) > fabs( proj2 ) )  // this means it is closer to p2 than p1
                    )
                        continue;  // basically, this means the intersection point is with a
                                   //  boundary edge on the other side, closer to p2 than p1, so we
                                   //  skip it
                    if( parPos == 0 )
                    {
                        // close to vertex 1, nothing to do
                        nodes.push_back( conn2[0] );
                        splittingNodes.push_back( conn2[0] );
                    }
                    else if( parPos == 1. )
                    {
                        // close to vertex 2, nothing to do
                        nodes.push_back( conn2[1] );
                        splittingNodes.push_back( conn2[1] );
                    }
                    else
                    {
                        // break the edge, create a new node at intersection point (will be smoothed
                        // out)
                        EntityHandle newVertex;
                        rval = _mbImpl->create_vertex( &( intx_point[0] ), newVertex );
                        MBERRORR( rval, "can't create vertex" );
                        nodes.push_back( newVertex );
                        split_internal_edge( candidateEdge, newVertex );
                        splittingNodes.push_back( newVertex );
                        _brokenEdges[newVertex] = candidateEdge;
                        _piercedEdges.insert( candidateEdge );
                    }
                    break;  // break from the loop over boundary edges, we are interested in the
                            // first
                            //      split (hopefully, the only split)
                }
            }
            if( ite == boundary_mesh_edges.end() )
                MBERRORR( MB_FAILURE, "Failed to find boundary intersection edge. Bail out" );
        }
        else
        {
            std::vector< double > distances_out;
            std::vector< EntityHandle > sets_out;
            std::vector< EntityHandle > facets_out;
            rval = _my_geomTopoTool->obb_tree()->ray_intersect_sets( distances_out, sets_out, facets_out, rootForFace,
                                                                     tolerance, point, dir );
            MBERRORR( rval, "Failed to get ray intersections." );
            if( distances_out.size() < 1 )
                MBERRORR( MB_FAILURE, "Failed to get one intersection point, bad direction." );

            if( distances_out.size() > 1 )
            {
                std::cout << " too many intersection points. Only the first one considered\n";
            }
            std::vector< EntityHandle >::iterator pFace = std::find( sets_out.begin(), sets_out.end(), face );

            if( pFace == sets_out.end() ) MBERRORR( MB_FAILURE, "Failed to intersect given face, bad direction." );
            unsigned int index = pFace - sets_out.begin();
            // get the closest node of the triangle, and modify locally the triangle(s), so the
            // intersection point is at a new vertex, if needed
            CartVect P( point );
            CartVect Dir( dir );
            CartVect newPoint = P + distances_out[index] * Dir;
            // get the triangle coordinates

            double area_coord[3];
            EntityHandle boundary_handle = 0;  // if 0, not on a boundary
            rval = area_coordinates( _mbImpl, facets_out[index], newPoint, area_coord, boundary_handle );
            MBERRORR( rval, "Failed to get area coordinates" );

            if( debug_splits )
            {
                std::cout << " int point:" << newPoint << " area coord " << area_coord[0] << " " << area_coord[1] << " "
                          << area_coord[2] << "\n";
                std::cout << " triangle: " << _mbImpl->id_from_handle( facets_out[index] )
                          << " boundary:" << boundary_handle << "\n";
            }
            EntityType type;
            if( boundary_handle ) type = _mbImpl->type_from_handle( boundary_handle );
            if( boundary_handle && ( type == MBVERTEX ) )
            {
                // nothing to do, we are happy
                nodes.push_back( boundary_handle );
            }
            else
            {
                // for an edge, we will split 2 triangles
                // for interior point, we will create 3 triangles out of one
                // create a new vertex
                EntityHandle newVertex;
                rval = _mbImpl->create_vertex( &( newPoint[0] ), newVertex );
                if( boundary_handle )  // this is edge
                {
                    split_internal_edge( boundary_handle, newVertex );
                    _piercedEdges.insert( boundary_handle );  // to be removed at the end
                }
                else
                    divide_triangle( facets_out[index], newVertex );

                nodes.push_back( newVertex );
            }
        }
    }
    // now, we have to find more intersection points, either interior to triangles, or on edges, or
    // on vertices use the same tolerance as before starting from 2 points on 2 triangles, and
    // having the direction, get more intersection points between the plane formed by direction and
    // those 2 points, and edges from triangulation (the triangles involved will be part of the same
    // gentity , original face ( moab set)
    // int closed = 1;// closed = 0 if the polyline is not closed

    CartVect Dir( direction );
    std::vector< EntityHandle > chainedEdges;

    for( i = 0; i < numIniPoints - 1 + closed; i++ )
    {
        int nextIndex = ( i + 1 ) % numIniPoints;
        std::vector< EntityHandle > trianglesAlong;
        std::vector< CartVect > points;
        // otherwise to edges or even nodes
        std::vector< EntityHandle > entities;
        // start with initial points, intersect along the direction, find the facets
        rval = compute_intersection_points( face, nodes[i], nodes[nextIndex], Dir, points, entities, trianglesAlong );
        MBERRORR( rval, "can't get intersection points along a line" );
        std::vector< EntityHandle > nodesAlongPolyline;
        // refactor code; move some edge creation for each 2 intersection points
        nodesAlongPolyline.push_back( entities[0] );  // it is for sure a node
        int num_points = (int)points.size();          // it should be num_triangles + 1
        for( int j = 0; j < num_points - 1; j++ )
        {
            EntityHandle tri = trianglesAlong[j];  // this is happening in trianglesAlong i
            EntityHandle e1  = entities[j];
            EntityHandle e2  = entities[j + 1];
            EntityType et1   = _mbImpl->type_from_handle( e1 );
            // EntityHandle vertex1 = nodesAlongPolyline[i];// irrespective of the entity type i,
            // we already have the vertex there
            EntityType et2 = _mbImpl->type_from_handle( e2 );
            if( et2 == MBVERTEX ) { nodesAlongPolyline.push_back( e2 ); }
            else  // if (et2==MBEDGE)
            {
                CartVect coord_vert = points[j + 1];
                EntityHandle newVertex;
                rval = _mbImpl->create_vertex( (double*)&coord_vert, newVertex );
                MBERRORR( rval, "can't create vertex" );
                nodesAlongPolyline.push_back( newVertex );
            }
            // if vertices, do not split anything, just get the edge for polyline
            if( et2 == MBVERTEX && et1 == MBVERTEX )
            {
                // nothing to do, just continue;
                continue;  // continue the for loop
            }

            if( debug_splits )
            {
                std::cout << "tri: type: " << _mbImpl->type_from_handle( tri )
                          << " id:" << _mbImpl->id_from_handle( tri ) << "\n    e1:" << e1
                          << " id:" << _mbImpl->id_from_handle( e1 ) << "   e2:" << e2
                          << " id:" << _mbImpl->id_from_handle( e2 ) << "\n";
            }
            // here, at least one is an edge
            rval = BreakTriangle2( tri, e1, e2, nodesAlongPolyline[j], nodesAlongPolyline[j + 1] );
            MBERRORR( rval, "can't break triangle 2" );
            if( et2 == MBEDGE ) _piercedEdges.insert( e2 );
            _piercedTriangles.insert( tri );
        }
        // nodesAlongPolyline will define a new geometric edge
        if( debug_splits )
        {
            std::cout << "nodesAlongPolyline: " << nodesAlongPolyline.size() << "\n";
            std::cout << "points: " << num_points << "\n";
        }
        // if needed, create edges along polyline, or revert the existing ones, to
        // put them in a new edge set
        EntityHandle new_geo_edge;
        rval = create_new_gedge( nodesAlongPolyline, new_geo_edge );
        MBERRORR( rval, "can't create a new edge" );
        chainedEdges.push_back( new_geo_edge );
        // end copy
    }
    // the segment between point_i and point_i+1 is in trianglesAlong_i
    // points_i is on entities_i
    // all these edges are oriented correctly
    rval = split_surface( face, chainedEdges, splittingNodes, oNewFace );
    MBERRORR( rval, "can't split surface" );
    //
    rval = chain_edges( min_dot );  // acos(0.8)~= 36 degrees
    MBERRORR( rval, "can't chain edges" );
    return MB_SUCCESS;
}
/**
 *  this method splits along the polyline defined by points and entities
 *  the polyline will be defined with
 *  // the entities are now only nodes and edges, no triangles!!!
 *  the first and last ones are also nodes for sure
 */
ErrorCode FBEngine::split_surface( EntityHandle face, std::vector< EntityHandle >& chainedEdges,
                                   std::vector< EntityHandle >& splittingNodes, EntityHandle& newFace )
{
    // use now the chained edges to create a new face (loop or clean split)
    // use a fill to determine the new sets, up to the polyline
    // points on the polyline will be moved to the closest point location, with some constraints
    // then the sets will be reset, geometry recomputed. new vertices, new edges, etc.

    Range iniTris;
    ErrorCode rval;
    rval = _mbImpl->get_entities_by_type( face, MBTRI, iniTris );
    MBERRORR( rval, "can't get initial triangles" );

    // start from a triangle that is not in the triangles to delete
    // flood fill

    bool closed = splittingNodes.size() == 0;
    if( !closed )
    {
        //
        if( splittingNodes.size() != 2 ) MBERRORR( MB_FAILURE, "need to have exactly 2 nodes for splitting" );
        // we will have to split the boundary edges
        // first, find the actual boundary, and try to split with the 2 end points (nodes)
        // get the adjacent edges, and see which one has the end nodes
        rval = split_boundary( face, splittingNodes[0] );
        MBERRORR( rval, "can't split with first node" );
        rval = split_boundary( face, splittingNodes[1] );
        MBERRORR( rval, "can't split with second node)" );
    }
    // we will separate triangles to delete, unaffected, new_triangles,
    //  nodesAlongPolyline,
    Range first, second;
    rval = separate( face, chainedEdges, first, second );

    // now, we are done with the computations;
    // we need to put the new nodes on the smooth surface
    if( this->_smooth )
    {
        rval = smooth_new_intx_points( face, chainedEdges );
        MBERRORR( rval, "can't smooth new points" );
    }

    // create the new set
    rval = _mbImpl->create_meshset( MESHSET_SET, newFace );
    MBERRORR( rval, "can't create a new face" );

    _my_geomTopoTool->add_geo_set( newFace, 2 );

    // the new face will have the first set (positive sense triangles, to the left)
    rval = _mbImpl->add_entities( newFace, first );
    MBERRORR( rval, "can't add first range triangles to new face" );

    for( unsigned int j = 0; j < chainedEdges.size(); j++ )
    {
        EntityHandle new_geo_edge = chainedEdges[j];
        // both faces will have the edge now
        rval = _mbImpl->add_parent_child( face, new_geo_edge );
        MBERRORR( rval, "can't add parent child relations for new edge" );

        rval = _mbImpl->add_parent_child( newFace, new_geo_edge );
        MBERRORR( rval, "can't add parent child relations for new edge" );
        // add senses
        // sense newFace is 1, old face is -1
        rval = _my_geomTopoTool->set_sense( new_geo_edge, newFace, 1 );
        MBERRORR( rval, "can't set sense for new edge" );

        rval = _my_geomTopoTool->set_sense( new_geo_edge, face, -1 );
        MBERRORR( rval, "can't set sense for new edge in original face" );
    }

    rval = set_neumann_tags( face, newFace );
    MBERRORR( rval, "can't set NEUMANN set tags" );

    // now, we should remove from the original set all tris, and put the "second" range
    rval = _mbImpl->remove_entities( face, iniTris );
    MBERRORR( rval, "can't remove original tris from initial face set" );

    rval = _mbImpl->add_entities( face, second );
    MBERRORR( rval, "can't add second range to the original set" );

    if( !closed )
    {
        rval = redistribute_boundary_edges_to_faces( face, newFace, chainedEdges );
        MBERRORR( rval, "fail to reset the proper boundary faces" );
    }

    /*if (_smooth)
      delete_smooth_tags();// they need to be recomputed, anyway
    // this will remove the extra smooth faces and edges
    clean();*/
    // also, these nodes need to be moved to the smooth surface, sometimes before deleting the old
    // triangles
    // remove the triangles from the set, then delete triangles (also some edges need to be
    // deleted!)
    rval = _mbImpl->delete_entities( _piercedTriangles );

    MBERRORR( rval, "can't delete triangles" );
    _piercedTriangles.clear();
    // delete edges that are broke up in 2
    rval = _mbImpl->delete_entities( _piercedEdges );
    MBERRORR( rval, "can't delete edges" );
    _piercedEdges.clear();

    if( debug_splits )
    {
        _mbImpl->write_file( "newFace.vtk", "vtk", 0, &newFace, 1 );
        _mbImpl->write_file( "leftoverFace.vtk", "vtk", 0, &face, 1 );
    }
    return MB_SUCCESS;
}

ErrorCode FBEngine::smooth_new_intx_points( EntityHandle face, std::vector< EntityHandle >& chainedEdges )
{

    // do not move nodes from the original face
    // first get all triangles, and then all nodes from those triangles

    Range tris;
    ErrorCode rval = _mbImpl->get_entities_by_type( face, MBTRI, tris );
    MBERRORR( rval, "can't get triangles" );

    Range ini_nodes;
    rval = _mbImpl->get_connectivity( tris, ini_nodes );
    MBERRORR( rval, "can't get connectivities" );

    SmoothFace* smthFace = _faces[face];

    // get all nodes from chained edges
    Range mesh_edges;
    for( unsigned int j = 0; j < chainedEdges.size(); j++ )
    {
        // keep adding to the range of mesh edges
        rval = _mbImpl->get_entities_by_dimension( chainedEdges[j], 1, mesh_edges );
        MBERRORR( rval, "can't get mesh edges" );
    }
    // nodes along polyline
    Range nodes_on_polyline;
    rval = _mbImpl->get_connectivity( mesh_edges, nodes_on_polyline, true );  // corners only
    MBERRORR( rval, "can't get nodes on the polyline" );

    Range new_intx_nodes = subtract( nodes_on_polyline, ini_nodes );

    std::vector< double > ini_coords;
    int num_points = (int)new_intx_nodes.size();
    ini_coords.resize( 3 * num_points );
    rval = _mbImpl->get_coords( new_intx_nodes, &( ini_coords[0] ) );
    MBERRORR( rval, "can't get coordinates" );

    int i = 0;
    for( Range::iterator it = new_intx_nodes.begin(); it != new_intx_nodes.end(); ++it )
    {
        /*EntityHandle node = *it;*/
        int i3 = 3 * i;
        smthFace->move_to_surface( ini_coords[i3], ini_coords[i3 + 1], ini_coords[i3 + 2] );
        // reset the coordinates of this node
        ++i;
    }
    rval = _mbImpl->set_coords( new_intx_nodes, &( ini_coords[0] ) );
    MBERRORR( rval, "can't set smoothed coordinates for the new nodes" );

    return MB_SUCCESS;
}
// we will use the fact that the splitting edge is oriented right now
// to the left will be new face, to the right, old face
// (to the left, positively oriented triangles)
ErrorCode FBEngine::separate( EntityHandle face, std::vector< EntityHandle >& chainedEdges, Range& first,
                              Range& second )
{
    // Range unaffectedTriangles = subtract(iniTriangles, _piercedTriangles);
    // insert in each
    // start with a new triangle, and flood to get the first range; what is left is the
    // second range
    // flood fill is considering edges adjacent to seed triangles; if there is
    //  an edge in the new_geo_edge, it is skipped; triangles in the
    // triangles to delete are not added
    // first, create all edges of the new triangles

    //
    // new face will have the new edge oriented positively
    // get mesh edges from geo edge (splitting gedge);

    Range mesh_edges;
    ErrorCode rval;
    // mesh_edges
    for( unsigned int j = 0; j < chainedEdges.size(); j++ )
    {
        // this will keep adding edges to the mesh_edges range
        // when we get out, the mesh_edges will be in this range, but not ordered
        rval = _mbImpl->get_entities_by_type( chainedEdges[j], MBEDGE, mesh_edges );
        MBERRORR( rval, "can't get new polyline edges" );
        if( debug_splits )
        {
            std::cout << " At chained edge " << j << " " << _mbImpl->id_from_handle( chainedEdges[j] )
                      << " mesh_edges Range size:" << mesh_edges.size() << "\n";
        }
    }

    // get a positive triangle adjacent to mesh_edge[0]
    // add to first triangles to the left, second triangles to the right of the mesh_edges ;

    // create a temp tag, and when done, delete it
    // default value: 0
    // 3 to be deleted, pierced
    // 1 first set
    // 2 second set
    // create the tag also for control points on the edges
    int defVal = 0;
    Tag separateTag;
    rval = MBI->tag_get_handle( "SEPARATE_TAG", 1, MB_TYPE_INTEGER, separateTag, MB_TAG_DENSE | MB_TAG_CREAT, &defVal );
    MBERRORR( rval, "can't create temp tag for separation" );
    // the deleted triangles will get a value 3, from start
    int delVal = 3;
    for( Range::iterator it1 = this->_piercedTriangles.begin(); it1 != _piercedTriangles.end(); ++it1 )
    {
        EntityHandle trToDelete = *it1;
        rval                    = _mbImpl->tag_set_data( separateTag, &trToDelete, 1, &delVal );
        MBERRORR( rval, "can't set delete tag value" );
    }

    // find a triangle that will be in the first range, positively oriented about the splitting edge
    EntityHandle seed1 = 0;
    for( Range::iterator it = mesh_edges.begin(); it != mesh_edges.end() && !seed1; ++it )
    {
        EntityHandle meshEdge = *it;
        Range adj_tri;
        rval = _mbImpl->get_adjacencies( &meshEdge, 1, 2, false, adj_tri );
        MBERRORR( rval, "can't get adj_tris to mesh edge" );

        for( Range::iterator it2 = adj_tri.begin(); it2 != adj_tri.end(); ++it2 )
        {
            EntityHandle tr = *it2;
            if( _piercedTriangles.find( tr ) != _piercedTriangles.end() )
                continue;  // do not attach pierced triangles, they are not good
            int num1, sense, offset;
            rval = _mbImpl->side_number( tr, meshEdge, num1, sense, offset );
            MBERRORR( rval, "edge not adjacent" );
            if( sense == 1 )
            {
                // firstSet.insert(tr);
                if( !seed1 )
                {
                    seed1 = tr;
                    break;
                }
            }
        }
    }

    // flood fill first set, the rest will be in second set
    // the edges from new_geo_edge will not be crossed

    // get edges of face (adjacencies)
    // also get the old boundary edges, from face; they will be edges to not cross, too
    Range bound_edges;
    rval = getAdjacentEntities( face, 1, bound_edges );
    MBERRORR( rval, "can't get boundary edges" );

    // add to the do not cross edges range, all edges from initial boundary
    Range initialBoundaryEdges;
    for( Range::iterator it = bound_edges.begin(); it != bound_edges.end(); ++it )
    {
        EntityHandle bound_edge = *it;
        rval                    = _mbImpl->get_entities_by_dimension( bound_edge, 1, initialBoundaryEdges );
    }

    Range doNotCrossEdges = unite( initialBoundaryEdges, mesh_edges );  // add the splitting edges !

    // use a second method, with tags
    //
    std::queue< EntityHandle > queue1;
    queue1.push( seed1 );
    std::vector< EntityHandle > arr1;
    while( !queue1.empty() )
    {
        // start copy
        EntityHandle currentTriangle = queue1.front();
        queue1.pop();
        arr1.push_back( currentTriangle );
        // add new triangles that share an edge
        Range currentEdges;
        rval = _mbImpl->get_adjacencies( &currentTriangle, 1, 1, true, currentEdges, Interface::UNION );
        MBERRORR( rval, "can't get adjacencies" );
        for( Range::iterator it = currentEdges.begin(); it != currentEdges.end(); ++it )
        {
            EntityHandle frontEdge = *it;
            if( doNotCrossEdges.find( frontEdge ) == doNotCrossEdges.end() )
            {
                // this is an edge that can be crossed
                Range adj_tri;
                rval = _mbImpl->get_adjacencies( &frontEdge, 1, 2, false, adj_tri, Interface::UNION );
                MBERRORR( rval, "can't get adj_tris" );
                // if the triangle is not in first range, add it to the queue
                for( Range::iterator it2 = adj_tri.begin(); it2 != adj_tri.end(); ++it2 )
                {
                    EntityHandle tri2 = *it2;
                    int val           = 0;
                    rval              = _mbImpl->tag_get_data( separateTag, &tri2, 1, &val );
                    MBERRORR( rval, "can't get tag value" );
                    if( val ) continue;
                    // else, set it to 1
                    val  = 1;
                    rval = _mbImpl->tag_set_data( separateTag, &tri2, 1, &val );
                    MBERRORR( rval, "can't get tag value" );

                    queue1.push( tri2 );
                }
            }  // end edge do not cross
        }      // end while
    }

    std::sort( arr1.begin(), arr1.end() );
    // Range first1;
    std::copy( arr1.rbegin(), arr1.rend(), range_inserter( first ) );

    // std::cout<< "\n first1.size() " << first1.size() << " first.size(): " << first.size() <<
    // "\n";
    if( debug_splits )
    {
        EntityHandle tmpSet;
        _mbImpl->create_meshset( MESHSET_SET, tmpSet );
        _mbImpl->add_entities( tmpSet, first );
        _mbImpl->write_file( "dbg1.vtk", "vtk", 0, &tmpSet, 1 );
    }
    // now, decide the set 2:
    // first, get all ini tris
    Range initr;
    rval = _mbImpl->get_entities_by_type( face, MBTRI, initr );
    MBERRORR( rval, "can't get tris " );
    second        = unite( initr, _newTriangles );
    Range second2 = subtract( second, _piercedTriangles );
    second        = subtract( second2, first );
    _newTriangles.clear();
    if( debug_splits )
    {
        std::cout << "\n second.size() " << second.size() << " first.size(): " << first.size() << "\n";
        // debugging code
        EntityHandle tmpSet2;
        _mbImpl->create_meshset( MESHSET_SET, tmpSet2 );
        _mbImpl->add_entities( tmpSet2, second );
        _mbImpl->write_file( "dbg2.vtk", "vtk", 0, &tmpSet2, 1 );
    }
    /*Range intex = intersect(first, second);
    if (!intex.empty() && debug_splits)
    {
      std::cout << "error, the sets should be disjoint\n";
      for (Range::iterator it1=intex.begin(); it1!=intex.end(); ++it1)
      {
        std::cout<<_mbImpl->id_from_handle(*it1) << "\n";
      }
    }*/
    rval = _mbImpl->tag_delete( separateTag );
    MBERRORR( rval, "can't delete tag " );
    return MB_SUCCESS;
}
// if there is an edge between 2 nodes, then check it's orientation, and revert it if needed
ErrorCode FBEngine::create_new_gedge( std::vector< EntityHandle >& nodesAlongPolyline, EntityHandle& new_geo_edge )
{

    ErrorCode rval = _mbImpl->create_meshset( MESHSET_ORDERED, new_geo_edge );
    MBERRORR( rval, "can't create geo edge" );

    // now, get the edges, or create if not existing
    std::vector< EntityHandle > mesh_edges;
    for( unsigned int i = 0; i < nodesAlongPolyline.size() - 1; i++ )
    {
        EntityHandle n1 = nodesAlongPolyline[i], n2 = nodesAlongPolyline[i + 1];

        EntityHandle nn2[2];
        nn2[0] = n1;
        nn2[1] = n2;

        std::vector< EntityHandle > adjacent;
        rval = _mbImpl->get_adjacencies( nn2, 2, 1, false, adjacent, Interface::INTERSECT );
        // see if there is an edge between those 2 already, and if it is oriented as we like
        bool new_edge = true;
        if( adjacent.size() >= 1 )
        {
            // check the orientation
            const EntityHandle* conn2 = NULL;
            int nnodes                = 0;
            rval                      = _mbImpl->get_connectivity( adjacent[0], conn2, nnodes );
            MBERRORR( rval, "can't get connectivity" );
            if( conn2[0] == nn2[0] && conn2[1] == nn2[1] )
            {
                // everything is fine
                mesh_edges.push_back( adjacent[0] );
                new_edge = false;  // we found one that's good, no need to create a new one
            }
            else
            {
                _piercedEdges.insert( adjacent[0] );  // we want to remove this one, it will be not needed
            }
        }
        if( new_edge )
        {
            // there is no edge between n1 and n2, create one
            EntityHandle mesh_edge;
            rval = _mbImpl->create_element( MBEDGE, nn2, 2, mesh_edge );
            MBERRORR( rval, "Failed to create a new edge" );
            mesh_edges.push_back( mesh_edge );
        }
    }

    // add loops edges to the edge set
    rval = _mbImpl->add_entities( new_geo_edge, &mesh_edges[0],
                                  mesh_edges.size() );  // only one edge
    MBERRORR( rval, "can't add edges to new_geo_set" );
    // check vertex sets for vertex 1 and vertex 2?
    // get all sets of dimension 0 from database, and see if our ends are here or not

    Range ends_geo_edge;
    ends_geo_edge.insert( nodesAlongPolyline[0] );
    ends_geo_edge.insert( nodesAlongPolyline[nodesAlongPolyline.size() - 1] );

    for( unsigned int k = 0; k < ends_geo_edge.size(); k++ )
    {
        EntityHandle node = ends_geo_edge[k];
        EntityHandle nodeSet;
        bool found = find_vertex_set_for_node( node, nodeSet );

        if( !found )
        {
            // create a node set and add the node

            rval = _mbImpl->create_meshset( MESHSET_SET, nodeSet );
            MBERRORR( rval, "Failed to create a new vertex set" );

            rval = _mbImpl->add_entities( nodeSet, &node, 1 );
            MBERRORR( rval, "Failed to add the node to the set" );

            rval = _my_geomTopoTool->add_geo_set( nodeSet, 0 );  //
            MBERRORR( rval, "Failed to commit the node set" );

            if( debug_splits )
            {
                std::cout << " create a vertex set " << _mbImpl->id_from_handle( nodeSet )
                          << " global id:" << this->_my_geomTopoTool->global_id( nodeSet ) << " for node " << node
                          << "\n";
            }
        }

        rval = _mbImpl->add_parent_child( new_geo_edge, nodeSet );
        MBERRORR( rval, "Failed to add parent child relation" );
    }
    // finally, put the edge in the range of edges
    rval = _my_geomTopoTool->add_geo_set( new_geo_edge, 1 );MB_CHK_ERR( rval );

    return rval;
}

void FBEngine::print_debug_triangle( EntityHandle t )
{
    std::cout << " triangle id:" << _mbImpl->id_from_handle( t ) << "\n";
    const EntityHandle* conn3 = NULL;
    int nnodes                = 0;
    _mbImpl->get_connectivity( t, conn3, nnodes );
    // get coords
    CartVect P[3];
    _mbImpl->get_coords( conn3, 3, (double*)&P[0] );
    std::cout << "  nodes:" << conn3[0] << " " << conn3[1] << " " << conn3[2] << "\n";
    CartVect PP[3];
    PP[0] = P[1] - P[0];
    PP[1] = P[2] - P[1];
    PP[2] = P[0] - P[2];

    std::cout << "  pos:" << P[0] << " " << P[1] << " " << P[2] << "\n";
    std::cout << "   x,y diffs " << PP[0][0] << " " << PP[0][1] << ",  " << PP[1][0] << " " << PP[1][1] << ",  "
              << PP[2][0] << " " << PP[2][1] << "\n";
    return;
}
// actual breaking of triangles
// case 1: n2 interior to triangle
ErrorCode FBEngine::BreakTriangle( EntityHandle, EntityHandle, EntityHandle, EntityHandle, EntityHandle, EntityHandle )
{
    std::cout << "FBEngine::BreakTriangle not implemented yet\n";
    return MB_FAILURE;
}
// case 2, n1 and n2 on boundary
ErrorCode FBEngine::BreakTriangle2( EntityHandle tri, EntityHandle e1, EntityHandle e2, EntityHandle n1,
                                    EntityHandle n2 )  // nodesAlongPolyline are on entities!
{
    // we have the nodes, we just need to reconnect to form new triangles
    ErrorCode rval;
    const EntityHandle* conn3 = NULL;
    int nnodes                = 0;
    rval                      = _mbImpl->get_connectivity( tri, conn3, nnodes );
    MBERRORR( rval, "Failed to get connectivity" );
    assert( 3 == nnodes );

    EntityType et1 = _mbImpl->type_from_handle( e1 );
    EntityType et2 = _mbImpl->type_from_handle( e2 );

    if( MBVERTEX == et1 )
    {
        // find the vertex in conn3, and form 2 other triangles
        int index = -1;
        for( index = 0; index < 3; index++ )
        {
            if( conn3[index] == e1 )  // also n1
                break;
        }
        if( index == 3 ) return MB_FAILURE;
        // 2 triangles: n1, index+1, n2, and n1, n2, index+2
        EntityHandle conn[6] = { n1, conn3[( index + 1 ) % 3], n2, n1, n2, conn3[( index + 2 ) % 3] };
        EntityHandle newTriangle;
        rval = _mbImpl->create_element( MBTRI, conn, 3, newTriangle );
        MBERRORR( rval, "Failed to create a new triangle" );
        _newTriangles.insert( newTriangle );
        if( debug_splits ) print_debug_triangle( newTriangle );
        rval = _mbImpl->create_element( MBTRI, conn + 3, 3, newTriangle );  // the second triangle
        MBERRORR( rval, "Failed to create a new triangle" );
        _newTriangles.insert( newTriangle );
        if( debug_splits ) print_debug_triangle( newTriangle );
    }
    else if( MBVERTEX == et2 )
    {
        int index = -1;
        for( index = 0; index < 3; index++ )
        {
            if( conn3[index] == e2 )  // also n2
                break;
        }
        if( index == 3 ) return MB_FAILURE;
        // 2 triangles: n1, index+1, n2, and n1, n2, index+2
        EntityHandle conn[6] = { n2, conn3[( index + 1 ) % 3], n1, n2, n1, conn3[( index + 2 ) % 3] };
        EntityHandle newTriangle;
        rval = _mbImpl->create_element( MBTRI, conn, 3, newTriangle );
        MBERRORR( rval, "Failed to create a new triangle" );
        _newTriangles.insert( newTriangle );
        if( debug_splits ) print_debug_triangle( newTriangle );
        rval = _mbImpl->create_element( MBTRI, conn + 3, 3, newTriangle );  // the second triangle
        MBERRORR( rval, "Failed to create a new triangle" );
        _newTriangles.insert( newTriangle );
        if( debug_splits ) print_debug_triangle( newTriangle );
    }
    else
    {
        // both are edges adjacent to triangle tri
        // there are several configurations possible for n1, n2, between conn3 nodes.
        int num1, num2, sense, offset;
        rval = _mbImpl->side_number( tri, e1, num1, sense, offset );
        MBERRORR( rval, "edge not adjacent" );

        rval = _mbImpl->side_number( tri, e2, num2, sense, offset );
        MBERRORR( rval, "edge not adjacent" );

        const EntityHandle* conn12;  // connectivity for edge 1
        const EntityHandle* conn22;  // connectivity for edge 2
        // int nnodes;
        rval = _mbImpl->get_connectivity( e1, conn12, nnodes );
        MBERRORR( rval, "Failed to get connectivity of edge 1" );
        assert( 2 == nnodes );
        rval = _mbImpl->get_connectivity( e2, conn22, nnodes );
        MBERRORR( rval, "Failed to get connectivity of edge 2" );
        assert( 2 == nnodes );
        // now, having the side number, work through
        if( debug_splits )
        {
            std::cout << "tri conn3:" << conn3[0] << " " << conn3[1] << " " << conn3[2] << "\n";
            std::cout << " edge1: conn12:" << conn12[0] << " " << conn12[1] << "  side: " << num1 << "\n";
            std::cout << " edge2: conn22:" << conn22[0] << " " << conn22[1] << "  side: " << num2 << "\n";
        }
        int unaffectedSide = 3 - num1 - num2;
        int i3             = ( unaffectedSide + 2 ) % 3;  // to 0 is 2, to 1 is 0, to 2 is 1
        // triangles will be formed with triVertexIndex , n1, n2 (in what order?)
        EntityHandle v1, v2;  // to hold the 2 nodes on edges
        if( num1 == i3 )
        {
            v1 = n1;
            v2 = n2;
        }
        else  // if (num2==i3)
        {
            v1 = n2;
            v2 = n1;
        }
        // three triangles are formed
        int i1 = ( i3 + 1 ) % 3;
        int i2 = ( i3 + 2 ) % 3;
        // we could break the surface differently
        EntityHandle conn[9] = { conn3[i3], v1, v2, v1, conn3[i1], conn3[i2], v2, v1, conn3[i2] };
        EntityHandle newTriangle;
        if( debug_splits ) std::cout << "Split 2 edges :\n";
        rval = _mbImpl->create_element( MBTRI, conn, 3, newTriangle );
        MBERRORR( rval, "Failed to create a new triangle" );
        _newTriangles.insert( newTriangle );
        if( debug_splits ) print_debug_triangle( newTriangle );
        rval = _mbImpl->create_element( MBTRI, conn + 3, 3, newTriangle );  // the second triangle
        MBERRORR( rval, "Failed to create a new triangle" );
        _newTriangles.insert( newTriangle );
        if( debug_splits ) print_debug_triangle( newTriangle );
        rval = _mbImpl->create_element( MBTRI, conn + 6, 3, newTriangle );  // the second triangle
        MBERRORR( rval, "Failed to create a new triangle" );
        _newTriangles.insert( newTriangle );
        if( debug_splits ) print_debug_triangle( newTriangle );
    }

    return MB_SUCCESS;
}

// build the list of intx points and entities from database involved
// vertices, edges, triangles
// it could be just a list of vertices (easiest case to handle after)

ErrorCode FBEngine::compute_intersection_points( EntityHandle&, EntityHandle from, EntityHandle to, CartVect& Dir,
                                                 std::vector< CartVect >& points, std::vector< EntityHandle >& entities,
                                                 std::vector< EntityHandle >& triangles )
{
    // keep a stack of triangles to process, and do not add those already processed
    // either mark them, or maybe keep them in a local set?
    // from and to are now nodes, start from them
    CartVect p1, p2;  // the position of from and to
    ErrorCode rval = _mbImpl->get_coords( &from, 1, (double*)&p1 );
    MBERRORR( rval, "failed to get 'from' coordinates" );
    rval = _mbImpl->get_coords( &to, 1, (double*)&p2 );
    MBERRORR( rval, "failed to get 'from' coordinates" );

    CartVect vect( p2 - p1 );
    double dist2 = vect.length();
    if( dist2 < tolerance_segment )
    {
        // we are done, return
        return MB_SUCCESS;
    }
    CartVect normPlane = Dir * vect;
    normPlane.normalize();
    std::set< EntityHandle > visitedTriangles;
    CartVect currentPoint = p1;
    // push the current point if it is empty
    if( points.size() == 0 )
    {
        points.push_back( p1 );
        entities.push_back( from );  // this is a node now
    }

    // these will be used in many loops
    CartVect intx = p1;  // somewhere to start
    double param  = -1.;

    // first intersection
    EntityHandle currentBoundary = from;  // it is a node, in the beginning

    vect = p2 - currentPoint;
    while( vect.length() > 0. )
    {
        // advance towards "to" node, from boundary handle
        EntityType etype = _mbImpl->type_from_handle( currentBoundary );
        // if vertex, look for other triangles connected which intersect our plane (defined by p1,
        // p2, dir)
        std::vector< EntityHandle > adj_tri;
        rval           = _mbImpl->get_adjacencies( &currentBoundary, 1, 2, false, adj_tri );
        unsigned int j = 0;
        EntityHandle tri;
        for( ; j < adj_tri.size(); j++ )
        {
            tri = adj_tri[j];
            if( visitedTriangles.find( tri ) != visitedTriangles.end() )
                continue;  // get another triangle, this one was already visited
            // check if it is one of the triangles that was pierced already
            if( _piercedTriangles.find( tri ) != _piercedTriangles.end() ) continue;
            // if vertex, look for opposite edge
            // if edge, look for 2 opposite edges
            // get vertices
            int nnodes;
            const EntityHandle* conn3;
            rval = _mbImpl->get_connectivity( tri, conn3, nnodes );
            MBERRORR( rval, "Failed to get connectivity" );
            // if one of the nodes is to, stop right there
            {
                if( conn3[0] == to || conn3[1] == to || conn3[2] == to )
                {
                    visitedTriangles.insert( tri );
                    triangles.push_back( tri );
                    currentPoint = p2;
                    points.push_back( p2 );
                    entities.push_back( to );  // we are done
                    break;                     // this is break from for loop, we still need to get out of while
                    // we will get out, because vect will become 0, (p2-p2)
                }
            }
            EntityHandle nn2[2];
            if( MBVERTEX == etype )
            {
                nn2[0] = conn3[0];
                nn2[1] = conn3[1];
                if( nn2[0] == currentBoundary ) nn2[0] = conn3[2];
                if( nn2[1] == currentBoundary ) nn2[1] = conn3[2];
                // get coordinates
                CartVect Pt[2];

                rval = _mbImpl->get_coords( nn2, 2, (double*)&Pt[0] );
                MBERRORR( rval, "Failed to get coordinates" );
                // see the intersection
                if( intersect_segment_and_plane_slice( Pt[0], Pt[1], currentPoint, p2, Dir, normPlane, intx, param ) )
                {
                    // we should stop for loop, and decide if it is edge or vertex
                    if( param == 0. )
                        currentBoundary = nn2[0];
                    else
                    {
                        if( param == 1. )
                            currentBoundary = nn2[1];
                        else  // param between 0 and 1, so edge
                        {
                            // find the edge between vertices
                            std::vector< EntityHandle > edges1;
                            // change the create flag to true, because that edge must exist in
                            // current triangle if we want to advance; nn2 are 2 nodes in current
                            // triangle!!
                            rval = _mbImpl->get_adjacencies( nn2, 2, 1, true, edges1, Interface::INTERSECT );
                            MBERRORR( rval, "Failed to get edges" );
                            if( edges1.size() != 1 ) MBERRORR( MB_FAILURE, "Failed to get adjacent edges to 2 nodes" );
                            currentBoundary = edges1[0];
                        }
                    }
                    visitedTriangles.insert( tri );
                    currentPoint = intx;
                    points.push_back( intx );
                    entities.push_back( currentBoundary );
                    triangles.push_back( tri );
                    if( debug_splits )
                        std::cout << "vtx new tri : " << _mbImpl->id_from_handle( tri )
                                  << " type bdy:" << _mbImpl->type_from_handle( currentBoundary ) << "\n";
                    break;  // out of for loop over triangles
                }
            }
            else  // this is MBEDGE, we have the other triangle to try out
            {
                // first find the nodes from existing boundary
                int nnodes2;
                const EntityHandle* conn2;
                rval = _mbImpl->get_connectivity( currentBoundary, conn2, nnodes2 );
                MBERRORR( rval, "Failed to get connectivity" );
                int thirdIndex = -1;
                for( int tj = 0; tj < 3; tj++ )
                {
                    if( ( conn3[tj] != conn2[0] ) && ( conn3[tj] != conn2[1] ) )
                    {
                        thirdIndex = tj;
                        break;
                    }
                }
                if( -1 == thirdIndex ) MBERRORR( MB_FAILURE, " can't get third node" );
                CartVect Pt[3];
                rval = _mbImpl->get_coords( conn3, 3, (double*)&Pt[0] );
                MBERRORR( rval, "Failed to get coords" );
                int indexFirst  = ( thirdIndex + 1 ) % 3;
                int indexSecond = ( thirdIndex + 2 ) % 3;
                int index[2]    = { indexFirst, indexSecond };
                for( int k = 0; k < 2; k++ )
                {
                    nn2[0] = conn3[index[k]], nn2[1] = conn3[thirdIndex];
                    if( intersect_segment_and_plane_slice( Pt[index[k]], Pt[thirdIndex], currentPoint, p2, Dir,
                                                           normPlane, intx, param ) )
                    {
                        // we should stop for loop, and decide if it is edge or vertex
                        if( param == 0. )
                            currentBoundary = conn3[index[k]];  // it is not really possible
                        else
                        {
                            if( param == 1. )
                                currentBoundary = conn3[thirdIndex];
                            else  // param between 0 and 1, so edge is fine
                            {
                                // find the edge between vertices
                                std::vector< EntityHandle > edges1;
                                // change the create flag to true, because that edge must exist in
                                // current triangle if we want to advance; nn2 are 2 nodes in
                                // current triangle!!
                                rval = _mbImpl->get_adjacencies( nn2, 2, 1, true, edges1, Interface::INTERSECT );
                                MBERRORR( rval, "Failed to get edges" );
                                if( edges1.size() != 1 )
                                    MBERRORR( MB_FAILURE, "Failed to get adjacent edges to 2 nodes" );
                                currentBoundary = edges1[0];
                            }
                        }
                        visitedTriangles.insert( tri );
                        currentPoint = intx;
                        points.push_back( intx );
                        entities.push_back( currentBoundary );
                        triangles.push_back( tri );
                        if( debug_splits )
                        {
                            std::cout << "edge new tri : " << _mbImpl->id_from_handle( tri )
                                      << "  type bdy: " << _mbImpl->type_from_handle( currentBoundary )
                                      << " id: " << _mbImpl->id_from_handle( currentBoundary ) << "\n";
                            _mbImpl->list_entity( currentBoundary );
                        }
                        break;  // out of for loop over triangles
                    }
                    // we should not reach here
                }
            }
        }
        /*if (j==adj_tri.size())
         {
         MBERRORR(MB_FAILURE, "did not advance");
         }*/
        vect = p2 - currentPoint;
    }

    if( debug_splits )
        std::cout << "nb entities: " << entities.size() << " triangles:" << triangles.size()
                  << " points.size(): " << points.size() << "\n";

    return MB_SUCCESS;
}

ErrorCode FBEngine::split_edge_at_point( EntityHandle edge, CartVect& point, EntityHandle& new_edge )
{
    // return MB_NOT_IMPLEMENTED;
    // first, we need to find the closest point on the smooth edge, then
    // split the smooth edge, then call the split_edge_at_mesh_node
    // or maybe just find the closest node??
    // first of all, we need to find a point on the smooth edge, close by
    // then split the mesh edge (if needed)
    // this would be quite a drama, as the new edge has to be inserted in
    // order for proper geo edge definition

    // first of all, find a closest point
    // usually called for
    if( debug_splits )
    {
        std::cout << "Split edge " << _mbImpl->id_from_handle( edge ) << " at point:" << point << "\n";
    }
    int dim = _my_geomTopoTool->dimension( edge );
    if( dim != 1 ) return MB_FAILURE;
    if( !_smooth ) return MB_FAILURE;  // call it only for smooth option...
    // maybe we should do something for linear too

    SmoothCurve* curve = this->_edges[edge];
    EntityHandle closeNode;
    int edgeIndex;
    double u = curve->u_from_position( point[0], point[1], point[2], closeNode, edgeIndex );
    if( 0 == closeNode )
    {
        // we really need to split an existing edge
        // do not do that yet
        // evaluate from u:
        /*double pos[3];
        curve->position_from_u(u,  pos[0], pos[1], pos[2] );*/
        // create a new node here, and split one edge
        // change also connectivity, create new triangles on both sides ...
        std::cout << "not found a close node,  u is: " << u << " edge index: " << edgeIndex << "\n";
        return MB_FAILURE;  // not implemented yet
    }
    return split_edge_at_mesh_node( edge, closeNode, new_edge );
}

ErrorCode FBEngine::split_edge_at_mesh_node( EntityHandle edge, EntityHandle node, EntityHandle& new_edge )
{
    // the node should be in the list of nodes

    int dim = _my_geomTopoTool->dimension( edge );
    if( dim != 1 ) return MB_FAILURE;  // not an edge

    if( debug_splits )
    {
        std::cout << "Split edge " << _mbImpl->id_from_handle( edge )
                  << " with global id: " << _my_geomTopoTool->global_id( edge )
                  << " at node:" << _mbImpl->id_from_handle( node ) << "\n";
    }

    // now get the edges
    // the order is important...
    // these are ordered sets !!
    std::vector< EntityHandle > ents;
    ErrorCode rval = _mbImpl->get_entities_by_type( edge, MBEDGE, ents );
    if( MB_SUCCESS != rval ) return rval;
    if( ents.size() < 1 ) return MB_FAILURE;  // no edges

    const EntityHandle* conn = NULL;
    int len;
    // find the edge connected to the splitting node
    int num_mesh_edges = (int)ents.size();
    int index_edge;
    EntityHandle firstNode = 0;
    for( index_edge = 0; index_edge < num_mesh_edges; index_edge++ )
    {
        rval = MBI->get_connectivity( ents[index_edge], conn, len );
        if( MB_SUCCESS != rval ) return rval;
        if( index_edge == 0 ) firstNode = conn[0];  // will be used to decide vertex sets adjacencies
        if( conn[0] == node )
        {
            if( index_edge == 0 )
            {
                new_edge = 0;       // no need to split, it is the first node
                return MB_SUCCESS;  // no split
            }
            else
                return MB_FAILURE;  // we should have found the node already , wrong
                                    // connectivity
        }
        else if( conn[1] == node )
        {
            // we found the index of interest
            break;
        }
    }
    if( index_edge == num_mesh_edges - 1 )
    {
        new_edge = 0;       // no need to split, it is the last node
        return MB_SUCCESS;  // no split
    }

    // here, we have 0 ... index_edge edges in the first set,
    // create a vertex set and add the node to it

    if( debug_splits )
    {
        std::cout << "Split edge with " << num_mesh_edges << " mesh edges, at index (0 based) " << index_edge << "\n";
    }

    // at this moment, the node set should have been already created in new_geo_edge
    EntityHandle nodeSet;  // the node set that has the node (find it!)
    bool found = find_vertex_set_for_node( node, nodeSet );

    if( !found )
    {
        // create a node set and add the node

        // must be an error, but create one nevertheless
        rval = _mbImpl->create_meshset( MESHSET_SET, nodeSet );
        MBERRORR( rval, "Failed to create a new vertex set" );

        rval = _mbImpl->add_entities( nodeSet, &node, 1 );
        MBERRORR( rval, "Failed to add the node to the set" );

        rval = _my_geomTopoTool->add_geo_set( nodeSet, 0 );  //
        MBERRORR( rval, "Failed to commit the node set" );

        if( debug_splits )
        {
            std::cout << " create a vertex set (this should have been created before!)"
                      << _mbImpl->id_from_handle( nodeSet )
                      << " global id:" << this->_my_geomTopoTool->global_id( nodeSet ) << "\n";
        }
    }

    // we need to remove the remaining mesh edges from first set, and add it
    // to the second set, in order

    rval = _mbImpl->create_meshset( MESHSET_ORDERED, new_edge );
    MBERRORR( rval, "can't create geo edge" );

    int remaining = num_mesh_edges - 1 - index_edge;

    // add edges to the edge set
    rval = _mbImpl->add_entities( new_edge, &ents[index_edge + 1], remaining );
    MBERRORR( rval, "can't add edges to the new edge" );

    // also, remove the second node set from old edge
    // remove the edges index_edge+1 and up

    rval = _mbImpl->remove_entities( edge, &ents[index_edge + 1], remaining );
    MBERRORR( rval, "can't remove edges from the old edge" );

    // need to find the adjacent vertex sets
    Range vertexRange;
    rval = getAdjacentEntities( edge, 0, vertexRange );

    EntityHandle secondSet;
    if( vertexRange.size() == 1 )
    {
        // initially a periodic edge, OK to add the new set to both edges, and the
        // second set
        secondSet = vertexRange[0];
    }
    else
    {
        if( vertexRange.size() > 2 ) return MB_FAILURE;  // something must be wrong with too many vertices
        // find first node
        int k;
        for( k = 0; k < 2; k++ )
        {
            Range verts;
            rval = _mbImpl->get_entities_by_type( vertexRange[k], MBVERTEX, verts );

            MBERRORR( rval, "can't get vertices from vertex set" );
            if( verts.size() != 1 ) MBERRORR( MB_FAILURE, " node set not defined well" );
            if( firstNode == verts[0] )
            {
                secondSet = vertexRange[1 - k];  // the other set; it is 1 or 0
                break;
            }
        }
        if( k >= 2 )
        {
            // it means we didn't find the right node set
            MBERRORR( MB_FAILURE, " can't find the right vertex" );
        }
        // remove the second set from the connectivity with the
        //  edge (parent-child relation)
        // remove_parent_child( EntityHandle parent,
        //                                          EntityHandle child )
        rval = _mbImpl->remove_parent_child( edge, secondSet );
        MBERRORR( rval, " can't remove the second vertex from edge" );
    }
    // at this point, we just need to add to both edges the new node set (vertex)
    rval = _mbImpl->add_parent_child( edge, nodeSet );
    MBERRORR( rval, " can't add new vertex to old edge" );

    rval = _mbImpl->add_parent_child( new_edge, nodeSet );
    MBERRORR( rval, " can't add new vertex to new edge" );

    // one thing that I forgot: add the secondSet as a child to new edge!!!
    // (so far, the new edge has only one end vertex!)
    rval = _mbImpl->add_parent_child( new_edge, secondSet );
    MBERRORR( rval, " can't add second vertex to new edge" );

    // now, add the edge and vertex to geo tool

    rval = _my_geomTopoTool->add_geo_set( new_edge, 1 );
    MBERRORR( rval, " can't add new edge" );

    // next, get the adjacent faces to initial edge, and add them as parents
    // to the new edge

    // need to find the adjacent face sets
    Range faceRange;
    rval = getAdjacentEntities( edge, 2, faceRange );

    // these faces will be adjacent to the new edge too!
    // need to set the senses of new edge within faces

    for( Range::iterator it = faceRange.begin(); it != faceRange.end(); ++it )
    {
        EntityHandle face = *it;
        rval              = _mbImpl->add_parent_child( face, new_edge );
        MBERRORR( rval, " can't add new edge - face parent relation" );
        int sense;
        rval = _my_geomTopoTool->get_sense( edge, face, sense );
        MBERRORR( rval, " can't get initial sense of edge in the adjacent face" );
        // keep the same sense for the new edge within the faces
        rval = _my_geomTopoTool->set_sense( new_edge, face, sense );
        MBERRORR( rval, " can't set sense of new edge in the adjacent face" );
    }

    return MB_SUCCESS;
}

ErrorCode FBEngine::split_bedge_at_new_mesh_node( EntityHandle edge, EntityHandle node, EntityHandle brokenEdge,
                                                  EntityHandle& new_edge )
{
    // the node should be in the list of nodes

    int dim = _my_geomTopoTool->dimension( edge );
    if( dim != 1 ) return MB_FAILURE;  // not an edge

    if( debug_splits )
    {
        std::cout << "Split edge " << _mbImpl->id_from_handle( edge )
                  << " with global id: " << _my_geomTopoTool->global_id( edge )
                  << " at new node:" << _mbImpl->id_from_handle( node ) << "breaking mesh edge"
                  << _mbImpl->id_from_handle( brokenEdge ) << "\n";
    }

    // now get the edges
    // the order is important...
    // these are ordered sets !!
    std::vector< EntityHandle > ents;
    ErrorCode rval = _mbImpl->get_entities_by_type( edge, MBEDGE, ents );
    if( MB_SUCCESS != rval ) return rval;
    if( ents.size() < 1 ) return MB_FAILURE;  // no edges

    const EntityHandle* conn = NULL;
    int len;
    // the edge connected to the splitting node is brokenEdge
    // find the small edges it is broken into, which are connected to
    // new vertex (node) and its ends; also, if necessary, reorient these small edges
    // for proper orientation
    rval = _mbImpl->get_connectivity( brokenEdge, conn, len );
    MBERRORR( rval, "Failed to get connectivity of broken edge" );

    // we already created the new edges, make sure they are oriented fine; if not, revert them
    EntityHandle conn02[] = { conn[0], node };  // first node and new node
    // default, intersect
    std::vector< EntityHandle > adj_edges;
    rval = _mbImpl->get_adjacencies( conn02, 2, 1, false, adj_edges );
    if( adj_edges.size() < 1 || rval != MB_SUCCESS ) MBERRORR( MB_FAILURE, " Can't find small split edge" );

    // get this edge connectivity;
    EntityHandle firstEdge         = adj_edges[0];
    const EntityHandle* connActual = NULL;
    rval                           = _mbImpl->get_connectivity( firstEdge, connActual, len );
    MBERRORR( rval, "Failed to get connectivity of first split edge" );
    // if it is the same as conn02, we are happy
    if( conn02[0] != connActual[0] )
    {
        // reset connectivity of edge
        rval = _mbImpl->set_connectivity( firstEdge, conn02, 2 );
        MBERRORR( rval, "Failed to reset connectivity of first split edge" );
    }
    //  now treat the second edge
    adj_edges.clear();                          //
    EntityHandle conn21[] = { node, conn[1] };  //  new node and second node
    rval                  = _mbImpl->get_adjacencies( conn21, 2, 1, false, adj_edges );
    if( adj_edges.size() < 1 || rval != MB_SUCCESS ) MBERRORR( MB_FAILURE, " Can't find second small split edge" );

    // get this edge connectivity;
    EntityHandle secondEdge = adj_edges[0];
    rval                    = _mbImpl->get_connectivity( firstEdge, connActual, len );
    MBERRORR( rval, "Failed to get connectivity of first split edge" );
    // if it is the same as conn21, we are happy
    if( conn21[0] != connActual[0] )
    {
        // reset connectivity of edge
        rval = _mbImpl->set_connectivity( secondEdge, conn21, 2 );
        MBERRORR( rval, "Failed to reset connectivity of first split edge" );
    }

    int num_mesh_edges = (int)ents.size();
    int index_edge;  // this is the index of the edge that will be removed (because it is split)
    // the rest of edges will be put in order in the (remaining) edge and new edge

    for( index_edge = 0; index_edge < num_mesh_edges; index_edge++ )
        if( brokenEdge == ents[index_edge] ) break;
    if( index_edge >= num_mesh_edges ) MBERRORR( MB_FAILURE, "can't find the broken edge" );

    // so the edges up to index_edge and firstEdge, will form the "old" edge
    // the edges secondEdge and from index_edge+1 to end will form the new_edge

    // here, we have 0 ... index_edge edges in the first set,
    // create a vertex set and add the node to it

    if( debug_splits )
    {
        std::cout << "Split edge with " << num_mesh_edges << " mesh edges, at index (0 based) " << index_edge << "\n";
    }

    // at this moment, the node set should have been already created in new_geo_edge
    EntityHandle nodeSet;  // the node set that has the node (find it!)
    bool found = find_vertex_set_for_node( node, nodeSet );

    if( !found )
    {
        // create a node set and add the node

        // must be an error, but create one nevertheless
        rval = _mbImpl->create_meshset( MESHSET_SET, nodeSet );
        MBERRORR( rval, "Failed to create a new vertex set" );

        rval = _mbImpl->add_entities( nodeSet, &node, 1 );
        MBERRORR( rval, "Failed to add the node to the set" );

        rval = _my_geomTopoTool->add_geo_set( nodeSet, 0 );  //
        MBERRORR( rval, "Failed to commit the node set" );

        if( debug_splits )
        {
            std::cout << " create a vertex set (this should have been created before!)"
                      << _mbImpl->id_from_handle( nodeSet )
                      << " global id:" << this->_my_geomTopoTool->global_id( nodeSet ) << "\n";
        }
    }

    // we need to remove the remaining mesh edges from first set, and add it
    // to the second set, in order

    rval = _mbImpl->create_meshset( MESHSET_ORDERED, new_edge );
    MBERRORR( rval, "can't create geo edge" );

    int remaining = num_mesh_edges - 1 - index_edge;

    // add edges to the new edge set
    rval = _mbImpl->add_entities( new_edge, &secondEdge, 1 );  // add the second split edge to new edge
    MBERRORR( rval, "can't add second split edge to the new edge" );
    // then add the rest
    rval = _mbImpl->add_entities( new_edge, &ents[index_edge + 1], remaining );
    MBERRORR( rval, "can't add edges to the new edge" );

    // also, remove the second node set from old edge
    // remove the edges index_edge and up

    rval = _mbImpl->remove_entities( edge, &ents[index_edge], remaining + 1 );  // include the
    MBERRORR( rval, "can't remove edges from the old edge" );
    // add the firstEdge too
    rval = _mbImpl->add_entities( edge, &firstEdge, 1 );  // add the second split edge to new edge
    MBERRORR( rval, "can't add first split edge to the old edge" );

    // need to find the adjacent vertex sets
    Range vertexRange;
    rval = getAdjacentEntities( edge, 0, vertexRange );

    EntityHandle secondSet;
    if( vertexRange.size() == 1 )
    {
        // initially a periodic edge, OK to add the new set to both edges, and the
        // second set
        secondSet = vertexRange[0];
    }
    else
    {
        if( vertexRange.size() > 2 ) return MB_FAILURE;  // something must be wrong with too many vertices
        // find first node
        EntityHandle firstNode;

        rval = MBI->get_connectivity( ents[0], conn, len );
        if( MB_SUCCESS != rval ) return rval;
        firstNode = conn[0];  // this is the first node of the initial edge
                              // we will use it to identify the vertex set associated with it
        int k;
        for( k = 0; k < 2; k++ )
        {
            Range verts;
            rval = _mbImpl->get_entities_by_type( vertexRange[k], MBVERTEX, verts );

            MBERRORR( rval, "can't get vertices from vertex set" );
            if( verts.size() != 1 ) MBERRORR( MB_FAILURE, " node set not defined well" );
            if( firstNode == verts[0] )
            {
                secondSet = vertexRange[1 - k];  // the other set; it is 1 or 0
                break;
            }
        }
        if( k >= 2 )
        {
            // it means we didn't find the right node set
            MBERRORR( MB_FAILURE, " can't find the right vertex" );
        }
        // remove the second set from the connectivity with the
        //  edge (parent-child relation)
        // remove_parent_child( EntityHandle parent,
        //                                          EntityHandle child )
        rval = _mbImpl->remove_parent_child( edge, secondSet );
        MBERRORR( rval, " can't remove the second vertex from edge" );
    }
    // at this point, we just need to add to both edges the new node set (vertex)
    rval = _mbImpl->add_parent_child( edge, nodeSet );
    MBERRORR( rval, " can't add new vertex to old edge" );

    rval = _mbImpl->add_parent_child( new_edge, nodeSet );
    MBERRORR( rval, " can't add new vertex to new edge" );

    // one thing that I forgot: add the secondSet as a child to new edge!!!
    // (so far, the new edge has only one end vertex!)
    rval = _mbImpl->add_parent_child( new_edge, secondSet );
    MBERRORR( rval, " can't add second vertex to new edge" );

    // now, add the edge and vertex to geo tool

    rval = _my_geomTopoTool->add_geo_set( new_edge, 1 );
    MBERRORR( rval, " can't add new edge" );

    // next, get the adjacent faces to initial edge, and add them as parents
    // to the new edge

    // need to find the adjacent face sets
    Range faceRange;
    rval = getAdjacentEntities( edge, 2, faceRange );

    // these faces will be adjacent to the new edge too!
    // need to set the senses of new edge within faces

    for( Range::iterator it = faceRange.begin(); it != faceRange.end(); ++it )
    {
        EntityHandle face = *it;
        rval              = _mbImpl->add_parent_child( face, new_edge );
        MBERRORR( rval, " can't add new edge - face parent relation" );
        int sense;
        rval = _my_geomTopoTool->get_sense( edge, face, sense );
        MBERRORR( rval, " can't get initial sense of edge in the adjacent face" );
        // keep the same sense for the new edge within the faces
        rval = _my_geomTopoTool->set_sense( new_edge, face, sense );
        MBERRORR( rval, " can't set sense of new edge in the adjacent face" );
    }

    return MB_SUCCESS;
}

ErrorCode FBEngine::split_boundary( EntityHandle face, EntityHandle atNode )
{
    // find the boundary edges, and split the one that we find it is a part of
    if( debug_splits )
    {
        std::cout << "Split face " << _mbImpl->id_from_handle( face )
                  << " at node:" << _mbImpl->id_from_handle( atNode ) << "\n";
    }
    Range bound_edges;
    ErrorCode rval = getAdjacentEntities( face, 1, bound_edges );
    MBERRORR( rval, " can't get boundary edges" );
    bool brokEdge = _brokenEdges.find( atNode ) != _brokenEdges.end();

    for( Range::iterator it = bound_edges.begin(); it != bound_edges.end(); ++it )
    {
        EntityHandle b_edge = *it;
        // get all edges in range
        Range mesh_edges;
        rval = _mbImpl->get_entities_by_dimension( b_edge, 1, mesh_edges );
        MBERRORR( rval, " can't get mesh edges" );
        if( brokEdge )
        {
            EntityHandle brokenEdge = _brokenEdges[atNode];
            if( mesh_edges.find( brokenEdge ) != mesh_edges.end() )
            {
                EntityHandle new_edge;
                rval = split_bedge_at_new_mesh_node( b_edge, atNode, brokenEdge, new_edge );
                return rval;
            }
        }
        else
        {
            Range nodes;
            rval = _mbImpl->get_connectivity( mesh_edges, nodes );
            MBERRORR( rval, " can't get nodes from mesh edges" );

            if( nodes.find( atNode ) != nodes.end() )
            {
                // we found our boundary edge candidate
                EntityHandle new_edge;
                rval = split_edge_at_mesh_node( b_edge, atNode, new_edge );
                return rval;
            }
        }
    }
    // if the node was not found in any "current" boundary, it broke an existing
    // boundary edge
    MBERRORR( MB_FAILURE, " we did not find an appropriate boundary edge" );
    ;  //
}

bool FBEngine::find_vertex_set_for_node( EntityHandle iNode, EntityHandle& oVertexSet )
{
    bool found = false;
    Range vertex_sets;

    const int zero               = 0;
    const void* const zero_val[] = { &zero };
    Tag geom_tag;
    ErrorCode rval = MBI->tag_get_handle( GEOM_DIMENSION_TAG_NAME, 1, MB_TYPE_INTEGER, geom_tag );
    if( MB_SUCCESS != rval ) return false;
    rval = _mbImpl->get_entities_by_type_and_tag( 0, MBENTITYSET, &geom_tag, zero_val, 1, vertex_sets );
    if( MB_SUCCESS != rval ) return false;
    // local _gsets, as we might have not updated the local lists
    // see if ends of geo edge generated is in a geo set 0 or not

    for( Range::iterator vsit = vertex_sets.begin(); vsit != vertex_sets.end(); ++vsit )
    {
        EntityHandle vset = *vsit;
        // is the node part of this set?
        if( _mbImpl->contains_entities( vset, &iNode, 1 ) )
        {

            found      = true;
            oVertexSet = vset;
            break;
        }
    }
    return found;
}
ErrorCode FBEngine::redistribute_boundary_edges_to_faces( EntityHandle face, EntityHandle newFace,
                                                          std::vector< EntityHandle >& chainedEdges )
{

    // so far, original boundary edges are all parent/child relations for face
    // we should get them all, and see if they are truly adjacent to face or newFace
    // decide also on the orientation/sense with respect to the triangles
    Range r1;  // range in old face
    Range r2;  // range of tris in new face
    ErrorCode rval = _mbImpl->get_entities_by_dimension( face, 2, r1 );
    MBERRORR( rval, " can't get triangles from old face" );
    rval = _mbImpl->get_entities_by_dimension( newFace, 2, r2 );
    MBERRORR( rval, " can't get triangles from new face" );
    // right now, all boundary edges are children of face
    // we need to get them all, and verify if they indeed are adjacent to face
    Range children;
    rval = _mbImpl->get_child_meshsets( face, children );  // only direct children are of interest
    MBERRORR( rval, " can't get children sets from face" );

    for( Range::iterator it = children.begin(); it != children.end(); ++it )
    {
        EntityHandle edge = *it;
        if( std::find( chainedEdges.begin(), chainedEdges.end(), edge ) != chainedEdges.end() )
            continue;  // we already set this one fine
        // get one mesh edge from the edge; we have to get all of them!!
        if( _my_geomTopoTool->dimension( edge ) != 1 ) continue;  // not an edge
        Range mesh_edges;
        rval = _mbImpl->get_entities_by_handle( edge, mesh_edges );
        MBERRORR( rval, " can't get mesh edges from edge" );
        if( mesh_edges.empty() ) MBERRORR( MB_FAILURE, " no mesh edges" );
        EntityHandle mesh_edge = mesh_edges[0];  // first one is enough
        // get its triangles; see which one is in r1 or r2; it should not be in both
        Range triangles;
        rval = _mbImpl->get_adjacencies( &mesh_edge, 1, 2, false, triangles );
        MBERRORR( rval, " can't get adjacent triangles" );
        Range intx1 = intersect( triangles, r1 );
        Range intx2 = intersect( triangles, r2 );
        if( !intx1.empty() && !intx2.empty() ) MBERRORR( MB_FAILURE, " at least one should be empty" );

        if( intx2.empty() )
        {
            // it means it is in the range r1; the sense should be fine, no need to reset
            // the sense should have been fine, also
            continue;
        }
        // so it must be a triangle in r2;
        EntityHandle triangle = intx2[0];  // one triangle only
        // remove the edge from boundary of face, and add it to the boundary of newFace
        // remove_parent_child( EntityHandle parent,  EntityHandle child )
        rval = _mbImpl->remove_parent_child( face, edge );
        MBERRORR( rval, " can't remove parent child relation for edge" );
        // add to the new face
        rval = _mbImpl->add_parent_child( newFace, edge );
        MBERRORR( rval, " can't add parent child relation for edge" );

        // set some sense, based on the sense of the mesh_edge in triangle
        int num1, sense, offset;
        rval = _mbImpl->side_number( triangle, mesh_edge, num1, sense, offset );
        MBERRORR( rval, "mesh edge not adjacent to triangle" );

        rval = this->_my_geomTopoTool->set_sense( edge, newFace, sense );
        MBERRORR( rval, "can't set proper sense of edge in face" );
    }

    return MB_SUCCESS;
}

ErrorCode FBEngine::set_neumann_tags( EntityHandle face, EntityHandle newFace )
{
    // these are for debugging purposes only
    // check the initial tag, then
    Tag ntag;
    ErrorCode rval = _mbImpl->tag_get_handle( NEUMANN_SET_TAG_NAME, 1, MB_TYPE_INTEGER, ntag );
    MBERRORR( rval, "can't get tag handle" );
    // check the value for face
    int nval;
    rval = _mbImpl->tag_get_data( ntag, &face, 1, &nval );
    if( MB_SUCCESS == rval ) { nval++; }
    else
    {
        nval = 1;
        rval = _mbImpl->tag_set_data( ntag, &face, 1, &nval );
        MBERRORR( rval, "can't set tag" );
        nval = 2;
    }
    rval = _mbImpl->tag_set_data( ntag, &newFace, 1, &nval );
    MBERRORR( rval, "can't set tag" );

    return MB_SUCCESS;
}

// split the quads if needed; it will create a new gtt, which will
// contain triangles instead of quads
ErrorCode FBEngine::split_quads()
{
    // first see if we have any quads in the 2d faces
    //  _my_gsets[2] is a range of surfaces (moab sets of dimension 2)
    int num_quads = 0;
    for( Range::iterator it = _my_gsets[2].begin(); it != _my_gsets[2].end(); ++it )
    {
        EntityHandle surface = *it;
        int num_q            = 0;
        _mbImpl->get_number_entities_by_type( surface, MBQUAD, num_q );
        num_quads += num_q;
    }

    if( num_quads == 0 ) return MB_SUCCESS;  // nothing to do

    GeomTopoTool* new_gtt = NULL;
    ErrorCode rval        = _my_geomTopoTool->duplicate_model( new_gtt );
    MBERRORR( rval, "can't duplicate model" );
    if( this->_t_created ) delete _my_geomTopoTool;

    _t_created = true;  // this one is for sure created here, even if the original gtt was not

    // if we were using smart pointers, we would decrease the reference to the _my_geomTopoTool, at
    // least
    _my_geomTopoTool = new_gtt;

    // replace the _my_gsets with the new ones, from the new set
    _my_geomTopoTool->find_geomsets( _my_gsets );

    // we have duplicated now the model, and the quads are part of the new _my_gsets[2]
    // we will split them now, by creating triangles along the smallest diagonal
    // maybe we will come up with a better criteria, but for the time being, it should be fine.
    // what we will do: we will remove all quads from the surface sets, and split them

    for( Range::iterator it2 = _my_gsets[2].begin(); it2 != _my_gsets[2].end(); ++it2 )
    {
        EntityHandle surface = *it2;
        Range quads;
        rval = _mbImpl->get_entities_by_type( surface, MBQUAD, quads );
        MBERRORR( rval, "can't get quads from the surface set" );
        rval = _mbImpl->remove_entities( surface, quads );
        MBERRORR( rval, "can't remove quads from the surface set" );  // they are not deleted, just
                                                                      // removed from the set
        for( Range::iterator it = quads.begin(); it != quads.end(); ++it )
        {
            EntityHandle quad = *it;
            int nnodes;
            const EntityHandle* conn;
            rval = _mbImpl->get_connectivity( quad, conn, nnodes );
            MBERRORR( rval, "can't get quad connectivity" );
            // get all vertices position, to see which one is the shortest diagonal
            CartVect pos[4];
            rval = _mbImpl->get_coords( conn, 4, (double*)&pos[0] );
            MBERRORR( rval, "can't get node coordinates" );
            bool diag1 = ( ( pos[2] - pos[0] ).length_squared() < ( pos[3] - pos[1] ).length_squared() );
            EntityHandle newTris[2];
            EntityHandle tri1[3] = { conn[0], conn[1], conn[2] };
            EntityHandle tri2[3] = { conn[0], conn[2], conn[3] };
            if( !diag1 )
            {
                tri1[2] = conn[3];
                tri2[0] = conn[1];
            }
            rval = _mbImpl->create_element( MBTRI, tri1, 3, newTris[0] );
            MBERRORR( rval, "can't create triangle 1" );
            rval = _mbImpl->create_element( MBTRI, tri2, 3, newTris[1] );
            MBERRORR( rval, "can't create triangle 2" );
            rval = _mbImpl->add_entities( surface, newTris, 2 );
            MBERRORR( rval, "can't add triangles to the set" );
        }
        //
    }
    return MB_SUCCESS;
}
ErrorCode FBEngine::boundary_mesh_edges_on_face( EntityHandle face, Range& boundary_mesh_edges )
{
    // this list is used only for finding the intersecting mesh edge for starting the
    // polygonal cutting line at boundary (if !closed)
    Range bound_edges;
    ErrorCode rval = getAdjacentEntities( face, 1, bound_edges );
    MBERRORR( rval, " can't get boundary edges" );
    for( Range::iterator it = bound_edges.begin(); it != bound_edges.end(); ++it )
    {
        EntityHandle b_edge = *it;
        // get all edges in range
        // Range mesh_edges;
        rval = _mbImpl->get_entities_by_dimension( b_edge, 1, boundary_mesh_edges );
        MBERRORR( rval, " can't get mesh edges" );
    }
    return MB_SUCCESS;
}
ErrorCode FBEngine::boundary_nodes_on_face( EntityHandle face, std::vector< EntityHandle >& boundary_nodes )
{
    // even if we repeat some nodes, it is OK
    // this list is used only for finding the closest boundary node for starting the
    // polygonal cutting line at boundary (if !closed)
    Range bound_edges;
    ErrorCode rval = getAdjacentEntities( face, 1, bound_edges );
    MBERRORR( rval, " can't get boundary edges" );
    Range b_nodes;
    for( Range::iterator it = bound_edges.begin(); it != bound_edges.end(); ++it )
    {
        EntityHandle b_edge = *it;
        // get all edges in range
        Range mesh_edges;
        rval = _mbImpl->get_entities_by_dimension( b_edge, 1, mesh_edges );
        MBERRORR( rval, " can't get mesh edges" );
        rval = _mbImpl->get_connectivity( mesh_edges, b_nodes );
        MBERRORR( rval, " can't get nodes from mesh edges" );
    }
    // create now a vector based on Range of nodes
    boundary_nodes.resize( b_nodes.size() );
    std::copy( b_nodes.begin(), b_nodes.end(), boundary_nodes.begin() );
    return MB_SUCCESS;
}
// used for splitting an edge
ErrorCode FBEngine::split_internal_edge( EntityHandle& edge, EntityHandle& newVertex )
{
    // split the edge, and form 4 new triangles and 2 edges
    // get 2 triangles adjacent to edge
    Range adj_tri;
    ErrorCode rval = _mbImpl->get_adjacencies( &edge, 1, 2, false, adj_tri );
    MBERRORR( rval, "can't get adj_tris" );
    adj_tri = subtract( adj_tri, _piercedTriangles );
    if( adj_tri.size() >= 3 ) { std::cout << "WARNING: non manifold geometry. Are you sure?"; }
    for( Range::iterator it = adj_tri.begin(); it != adj_tri.end(); ++it )
    {
        EntityHandle tri = *it;
        _piercedTriangles.insert( tri );
        const EntityHandle* conn3;
        int nnodes;
        rval = _mbImpl->get_connectivity( tri, conn3, nnodes );
        MBERRORR( rval, "can't get nodes" );
        int num1, sense, offset;
        rval = _mbImpl->side_number( tri, edge, num1, sense, offset );
        MBERRORR( rval, "can't get side number" );
        // after we know the side number, we can split in 2 triangles
        // node i is opposite to edge i
        int num2 = ( num1 + 1 ) % 3;
        int num3 = ( num2 + 1 ) % 3;
        // the edge from num1 to num2 is split into 2 edges
        EntityHandle t1[] = { conn3[num2], conn3[num3], newVertex };
        EntityHandle t2[] = { conn3[num1], newVertex, conn3[num3] };
        EntityHandle newTriangle, newTriangle2;
        rval = _mbImpl->create_element( MBTRI, t1, 3, newTriangle );
        MBERRORR( rval, "can't create triangle" );
        _newTriangles.insert( newTriangle );
        rval = _mbImpl->create_element( MBTRI, t2, 3, newTriangle2 );
        MBERRORR( rval, "can't create triangle" );
        _newTriangles.insert( newTriangle2 );
        // create edges with this, indirectly
        std::vector< EntityHandle > edges0;
        rval = _mbImpl->get_adjacencies( &newTriangle, 1, 1, true, edges0 );
        MBERRORR( rval, "can't get new edges" );
        edges0.clear();
        rval = _mbImpl->get_adjacencies( &newTriangle2, 1, 1, true, edges0 );
        MBERRORR( rval, "can't get new edges" );
        if( debug_splits )
        {
            std::cout << "2 (out of 4) triangles formed:\n";
            _mbImpl->list_entity( newTriangle );
            print_debug_triangle( newTriangle );
            _mbImpl->list_entity( newTriangle2 );
            print_debug_triangle( newTriangle2 );
        }
    }
    return MB_SUCCESS;
}
// triangle split
ErrorCode FBEngine::divide_triangle( EntityHandle triangle, EntityHandle& newVertex )
{
    //
    _piercedTriangles.insert( triangle );
    int nnodes                = 0;
    const EntityHandle* conn3 = NULL;
    ErrorCode rval            = _mbImpl->get_connectivity( triangle, conn3, nnodes );
    MBERRORR( rval, "can't get nodes" );
    EntityHandle t1[] = { conn3[0], conn3[1], newVertex };
    EntityHandle t2[] = { conn3[1], conn3[2], newVertex };
    EntityHandle t3[] = { conn3[2], conn3[0], newVertex };
    EntityHandle newTriangle, newTriangle2, newTriangle3;
    rval = _mbImpl->create_element( MBTRI, t1, 3, newTriangle );
    MBERRORR( rval, "can't create triangle" );
    _newTriangles.insert( newTriangle );
    rval = _mbImpl->create_element( MBTRI, t2, 3, newTriangle3 );
    MBERRORR( rval, "can't create triangle" );
    _newTriangles.insert( newTriangle3 );
    rval = _mbImpl->create_element( MBTRI, t3, 3, newTriangle2 );
    MBERRORR( rval, "can't create triangle" );
    _newTriangles.insert( newTriangle2 );

    // create all edges
    std::vector< EntityHandle > edges0;
    rval = _mbImpl->get_adjacencies( &newTriangle, 1, 1, true, edges0 );
    MBERRORR( rval, "can't get new edges" );
    edges0.clear();
    rval = _mbImpl->get_adjacencies( &newTriangle2, 1, 1, true, edges0 );
    MBERRORR( rval, "can't get new edges" );
    if( debug_splits )
    {
        std::cout << "3 triangles formed:\n";
        _mbImpl->list_entity( newTriangle );
        print_debug_triangle( newTriangle );
        _mbImpl->list_entity( newTriangle3 );
        print_debug_triangle( newTriangle3 );
        _mbImpl->list_entity( newTriangle2 );
        print_debug_triangle( newTriangle2 );
        std::cout << "original nodes in tri:\n";
        _mbImpl->list_entity( conn3[0] );
        _mbImpl->list_entity( conn3[1] );
        _mbImpl->list_entity( conn3[2] );
    }
    return MB_SUCCESS;
}

ErrorCode FBEngine::create_volume_with_direction( EntityHandle newFace1, EntityHandle newFace2, double* direction,
                                                  EntityHandle& volume )
{

    // MESHSET
    // ErrorCode rval = _mbImpl->create_meshset(MESHSET_ORDERED, new_geo_edge);
    ErrorCode rval = _mbImpl->create_meshset( MESHSET_SET, volume );
    MBERRORR( rval, "can't create volume" );

    int volumeMatId = 1;  // just give a mat id, for debugging, mostly
    Tag matTag;
    rval = _mbImpl->tag_get_handle( MATERIAL_SET_TAG_NAME, 1, MB_TYPE_INTEGER, matTag );
    MBERRORR( rval, "can't get material tag" );

    rval = _mbImpl->tag_set_data( matTag, &volume, 1, &volumeMatId );
    MBERRORR( rval, "can't set material tag value on volume" );

    // get the edges of those 2 faces, and get the vertices of those edges
    // in order, they should be created in the same order (?); check for that, anyway
    rval = _mbImpl->add_parent_child( volume, newFace1 );
    MBERRORR( rval, "can't add first face to volume" );

    rval = _mbImpl->add_parent_child( volume, newFace2 );
    MBERRORR( rval, "can't add second face to volume" );

    // first is bottom, so it is negatively oriented
    rval = _my_geomTopoTool->add_geo_set( volume, 3 );
    MBERRORR( rval, "can't add volume to the gtt" );

    // set senses
    // bottom face is negatively oriented, its normal is toward interior of the volume
    rval = _my_geomTopoTool->set_sense( newFace1, volume, -1 );
    MBERRORR( rval, "can't set bottom face sense to the volume" );

    // the top face is positively oriented
    rval = _my_geomTopoTool->set_sense( newFace2, volume, 1 );
    MBERRORR( rval, "can't set top face sense to the volume" );

    // the children should be in the same direction
    //   get the side edges of each face, and form lateral faces, along direction
    std::vector< EntityHandle > edges1;
    std::vector< EntityHandle > edges2;

    rval = _mbImpl->get_child_meshsets( newFace1, edges1 );  // no hops
    MBERRORR( rval, "can't get children edges or first face, bottom" );

    rval = _mbImpl->get_child_meshsets( newFace2, edges2 );  // no hops
    MBERRORR( rval, "can't get children edges for second face, top" );

    if( edges1.size() != edges2.size() ) MBERRORR( MB_FAILURE, "wrong correspondence " );

    for( unsigned int i = 0; i < edges1.size(); ++i )
    {
        EntityHandle newLatFace;
        rval = weave_lateral_face_from_edges( edges1[i], edges2[i], direction, newLatFace );
        MBERRORR( rval, "can't weave lateral face" );
        rval = _mbImpl->add_parent_child( volume, newLatFace );
        MBERRORR( rval, "can't add lateral face to volume" );

        // set sense as positive
        rval = _my_geomTopoTool->set_sense( newLatFace, volume, 1 );
        MBERRORR( rval, "can't set lateral face sense to the volume" );
    }

    rval = set_default_neumann_tags();
    MBERRORR( rval, "can't set new neumann tags" );

    return MB_SUCCESS;
}

ErrorCode FBEngine::get_nodes_from_edge( EntityHandle gedge, std::vector< EntityHandle >& nodes )
{
    std::vector< EntityHandle > ents;
    ErrorCode rval = _mbImpl->get_entities_by_type( gedge, MBEDGE, ents );
    if( MB_SUCCESS != rval ) return rval;
    if( ents.size() < 1 ) return MB_FAILURE;

    nodes.resize( ents.size() + 1 );
    const EntityHandle* conn = NULL;
    int len;
    for( unsigned int i = 0; i < ents.size(); ++i )
    {
        rval = _mbImpl->get_connectivity( ents[i], conn, len );
        MBERRORR( rval, "can't get edge connectivity" );
        nodes[i] = conn[0];
    }
    // the last one is conn[1]
    nodes[ents.size()] = conn[1];
    return MB_SUCCESS;
}
ErrorCode FBEngine::weave_lateral_face_from_edges( EntityHandle bEdge, EntityHandle tEdge, double* direction,
                                                   EntityHandle& newLatFace )
{
    // in weird cases might need to create new vertices in the interior;
    // in most cases, it is OK

    ErrorCode rval = _mbImpl->create_meshset( MESHSET_SET, newLatFace );
    MBERRORR( rval, "can't create new lateral face" );

    EntityHandle v[4];  // vertex sets
    // bot edge will be v1->v2
    // top edge will be v3->v4
    // we need to create edges from v1 to v3 and from v2 to v4
    std::vector< EntityHandle > adj;
    rval = _mbImpl->get_child_meshsets( bEdge, adj );
    MBERRORR( rval, "can't get children nodes" );
    bool periodic = false;
    if( adj.size() == 1 )
    {
        v[0] = v[1] = adj[0];
        periodic    = true;
    }
    else
    {
        v[0] = adj[0];
        v[1] = adj[1];
    }
    int senseB;
    rval = getEgVtxSense( bEdge, v[0], v[1], senseB );
    MBERRORR( rval, "can't get bottom edge sense" );
    if( -1 == senseB )
    {
        v[1] = adj[0];  // so , bEdge will be oriented from v[0] to v[1], and will start at
                        // nodes1, coords1..
        v[0] = adj[1];
    }
    adj.clear();
    rval = _mbImpl->get_child_meshsets( tEdge, adj );
    MBERRORR( rval, "can't get children nodes" );
    if( adj.size() == 1 )
    {
        v[2] = v[3] = adj[0];
        if( !periodic ) MBERRORR( MB_FAILURE, "top edge is periodic, but bottom edge is not" );
    }
    else
    {
        v[2] = adj[0];
        v[3] = adj[1];
        if( periodic ) MBERRORR( MB_FAILURE, "top edge is not periodic, but bottom edge is" );
    }

    // now, using nodes on bottom edge and top edge, create triangles, oriented outwards the
    //  volume (sense positive on bottom edge)
    std::vector< EntityHandle > nodes1;
    rval = get_nodes_from_edge( bEdge, nodes1 );
    MBERRORR( rval, "can't get nodes from bott edge" );

    std::vector< EntityHandle > nodes2;
    rval = get_nodes_from_edge( tEdge, nodes2 );
    MBERRORR( rval, "can't get nodes from top edge" );

    std::vector< CartVect > coords1, coords2;
    coords1.resize( nodes1.size() );
    coords2.resize( nodes2.size() );

    int N1 = (int)nodes1.size();
    int N2 = (int)nodes2.size();

    rval = _mbImpl->get_coords( &( nodes1[0] ), nodes1.size(), (double*)&( coords1[0] ) );
    MBERRORR( rval, "can't get coords of nodes from bott edge" );

    rval = _mbImpl->get_coords( &( nodes2[0] ), nodes2.size(), (double*)&( coords2[0] ) );
    MBERRORR( rval, "can't get coords of nodes from top edge" );
    CartVect up( direction );

    // see if the start and end coordinates are matching, if not, reverse edge 2 nodes and
    // coordinates
    CartVect v1 = ( coords1[0] - coords2[0] ) * up;
    CartVect v2 = ( coords1[0] - coords2[N2 - 1] ) * up;
    if( v1.length_squared() > v2.length_squared() )
    {
        // we need to reverse coords2 and node2, as nodes are not above each other
        // the edges need to be found between v0 and v3, v1 and v2!
        for( unsigned int k = 0; k < nodes2.size() / 2; k++ )
        {
            EntityHandle tmp    = nodes2[k];
            nodes2[k]           = nodes2[N2 - 1 - k];
            nodes2[N2 - 1 - k]  = tmp;
            CartVect tv         = coords2[k];
            coords2[k]          = coords2[N2 - 1 - k];
            coords2[N2 - 1 - k] = tv;
        }
    }
    // make sure v[2] has nodes2[0], if not, reverse v[2] and v[3]
    if( !_mbImpl->contains_entities( v[2], &( nodes2[0] ), 1 ) )
    {
        // reverse v[2] and v[3], so v[2] will be above v[0]
        EntityHandle tmp = v[2];
        v[2]             = v[3];
        v[3]             = tmp;
    }
    // now we know that v[0]--v[3] will be vertex sets in the order we want
    EntityHandle nd[4] = { nodes1[0], nodes1[N1 - 1], nodes2[0], nodes2[N2 - 1] };

    adj.clear();
    EntityHandle e1, e2;
    // find edge 1 between v[0] and v[2], and e2 between v[1] and v[3]
    rval = _mbImpl->get_parent_meshsets( v[0], adj );
    MBERRORR( rval, "can't get edges connected to vertex set 1" );
    bool found = false;
    for( unsigned int j = 0; j < adj.size(); j++ )
    {
        EntityHandle ed = adj[j];
        Range vertices;
        rval = _mbImpl->get_child_meshsets( ed, vertices );
        if( vertices.find( v[2] ) != vertices.end() )
        {
            found = true;
            e1    = ed;
            break;
        }
    }
    if( !found )
    {
        // create an edge from v[0] to v[2]
        rval = _mbImpl->create_meshset( MESHSET_SET, e1 );
        MBERRORR( rval, "can't create edge 1" );

        rval = _mbImpl->add_parent_child( e1, v[0] );
        MBERRORR( rval, "can't add parent - child relation" );

        rval = _mbImpl->add_parent_child( e1, v[2] );
        MBERRORR( rval, "can't add parent - child relation" );

        EntityHandle nn2[2] = { nd[0], nd[2] };
        EntityHandle medge;
        rval = _mbImpl->create_element( MBEDGE, nn2, 2, medge );
        MBERRORR( rval, "can't create mesh edge" );

        rval = _mbImpl->add_entities( e1, &medge, 1 );
        MBERRORR( rval, "can't add mesh edge to geo edge" );

        rval = this->_my_geomTopoTool->add_geo_set( e1, 1 );
        MBERRORR( rval, "can't add edge to gtt" );
    }

    // find the edge from v2 to v4 (if not, create one)
    rval = _mbImpl->get_parent_meshsets( v[1], adj );
    MBERRORR( rval, "can't get edges connected to vertex set 2" );
    found = false;
    for( unsigned int i = 0; i < adj.size(); i++ )
    {
        EntityHandle ed = adj[i];
        Range vertices;
        rval = _mbImpl->get_child_meshsets( ed, vertices );
        if( vertices.find( v[3] ) != vertices.end() )
        {
            found = true;
            e2    = ed;
            break;
        }
    }
    if( !found )
    {
        // create an edge from v2 to v4
        rval = _mbImpl->create_meshset( MESHSET_SET, e2 );
        MBERRORR( rval, "can't create edge 1" );

        rval = _mbImpl->add_parent_child( e2, v[1] );
        MBERRORR( rval, "can't add parent - child relation" );

        rval = _mbImpl->add_parent_child( e2, v[3] );
        MBERRORR( rval, "can't add parent - child relation" );

        EntityHandle nn2[2] = { nd[1], nd[3] };
        EntityHandle medge;
        rval = _mbImpl->create_element( MBEDGE, nn2, 2, medge );
        MBERRORR( rval, "can't create mesh edge" );

        rval = _mbImpl->add_entities( e2, &medge, 1 );
        MBERRORR( rval, "can't add mesh edge to geo edge" );

        rval = _my_geomTopoTool->add_geo_set( e2, 1 );
        MBERRORR( rval, "can't add edge to gtt" );
    }

    // now we have the four edges, add them to the face, as children

    // add children to face
    rval = _mbImpl->add_parent_child( newLatFace, bEdge );
    MBERRORR( rval, "can't add parent - child relation" );

    rval = _mbImpl->add_parent_child( newLatFace, tEdge );
    MBERRORR( rval, "can't add parent - child relation" );

    rval = _mbImpl->add_parent_child( newLatFace, e1 );
    MBERRORR( rval, "can't add parent - child relation" );

    rval = _mbImpl->add_parent_child( newLatFace, e2 );
    MBERRORR( rval, "can't add parent - child relation" );

    rval = _my_geomTopoTool->add_geo_set( newLatFace, 2 );
    MBERRORR( rval, "can't add face to gtt" );
    // add senses
    //
    rval = _my_geomTopoTool->set_sense( bEdge, newLatFace, 1 );
    MBERRORR( rval, "can't set bottom edge sense to the lateral face" );

    int Tsense;
    rval = getEgVtxSense( tEdge, v[3], v[2], Tsense );
    MBERRORR( rval, "can't get top edge sense" );
    // we need to see what sense has topEdge in face
    rval = _my_geomTopoTool->set_sense( tEdge, newLatFace, Tsense );
    MBERRORR( rval, "can't set top edge sense to the lateral face" );

    rval = _my_geomTopoTool->set_sense( e1, newLatFace, -1 );
    MBERRORR( rval, "can't set first vert edge sense" );

    rval = _my_geomTopoTool->set_sense( e2, newLatFace, 1 );
    MBERRORR( rval, "can't set second edge sense to the lateral face" );
    // first, create edges along direction, for the

    int indexB = 0, indexT = 0;  // indices of the current nodes in the weaving process
    // weaving is either up or down; the triangles are oriented positively either way
    // up is nodes1[indexB], nodes2[indexT+1], nodes2[indexT]
    // down is nodes1[indexB], nodes1[indexB+1], nodes2[indexT]
    // the decision to weave up or down is based on which one is closer to the direction normal
    /*
     *
     *     --------*------*-----------*                           ^
     *            /   .    \ .      .           ------> dir1      |  up
     *           /.         \   .  .                              |
     *     -----*------------*----*
     *
     */
    // we have to change the logic to account for cases when the curve in xy plane is not straight
    // (for example, when merging curves with a min_dot < -0.5, which means that the edges
    // could be even closed (periodic), with one vertex
    // the top and bottom curves should follow the same path in the "xy" plane (better to say
    // the plane perpendicular to the direction of weaving)
    // in this logic, the vector dir1 varies along the curve !!!
    CartVect dir1 = coords1[1] - coords1[0];  // we should have at least 2 nodes, N1>=2!!

    CartVect planeNormal = dir1 * up;
    dir1                 = up * planeNormal;
    dir1.normalize();
    // this direction will be updated constantly with the direction of last edge added
    bool weaveDown = true;

    CartVect startP = coords1[0];  // used for origin of comparisons
    while( 1 )
    {
        if( ( indexB == N1 - 1 ) && ( indexT == N2 - 1 ) ) break;  // we cannot advance anymore
        if( indexB == N1 - 1 ) { weaveDown = false; }
        else if( indexT == N2 - 1 )
        {
            weaveDown = true;
        }
        else
        {
            // none are at the end, we have to decide which way to go, based on which  index + 1 is
            // closer
            double proj1 = ( coords1[indexB + 1] - startP ) % dir1;
            double proj2 = ( coords2[indexT + 1] - startP ) % dir1;
            if( proj1 < proj2 )
                weaveDown = true;
            else
                weaveDown = false;
        }
        EntityHandle nTri[3] = { nodes1[indexB], 0, nodes2[indexT] };
        if( weaveDown )
        {
            nTri[1] = nodes1[indexB + 1];
            nTri[2] = nodes2[indexT];
            indexB++;
        }
        else
        {
            nTri[1] = nodes2[indexT + 1];
            indexT++;
        }
        EntityHandle triangle;
        rval = _mbImpl->create_element( MBTRI, nTri, 3, triangle );
        MBERRORR( rval, "can't create triangle" );

        rval = _mbImpl->add_entities( newLatFace, &triangle, 1 );
        MBERRORR( rval, "can't add triangle to face set" );
        if( weaveDown )
        {
            // increase was from nodes1[indexB-1] to nodes1[indexb]
            dir1 = coords1[indexB] - coords1[indexB - 1];  // we should have at least 2 nodes, N1>=2!!
        }
        else
        {
            dir1 = coords2[indexT] - coords2[indexT - 1];
        }
        dir1 = up * ( dir1 * up );
        dir1.normalize();
    }
    // we do not check yet if the triangles are inverted
    // if yes, we should correct them. HOW?
    // we probably need a better meshing strategy, one that can overcome really bad meshes.
    // again, these faces are not what we should use for geometry, maybe we should use the
    //  extruded quads, identified AFTER hexa are created.
    // right now, I see only a cosmetic use of these lateral faces
    // the whole idea of volume maybe is overrated
    // volume should be just quads extruded from bottom ?
    //
    return MB_SUCCESS;
}
// this will be used during creation of the volume, to set unique
// tags on all surfaces
// it is changing original tags, so do not use it if you want to preserve
// initial neumann tags
ErrorCode FBEngine::set_default_neumann_tags()
{
    // these are for debugging purposes only
    // check the initial tag, then
    Tag ntag;
    ErrorCode rval = _mbImpl->tag_get_handle( NEUMANN_SET_TAG_NAME, 1, MB_TYPE_INTEGER, ntag );
    MBERRORR( rval, "can't get tag handle" );
    // get all surfaces in the model now
    Range sets[5];
    rval = _my_geomTopoTool->find_geomsets( sets );
    MBERRORR( rval, "can't get geo sets" );
    int nfaces = (int)sets[2].size();
    int* vals  = new int[nfaces];
    for( int i = 0; i < nfaces; i++ )
    {
        vals[i] = i + 1;
    }
    rval = _mbImpl->tag_set_data( ntag, sets[2], (void*)vals );
    MBERRORR( rval, "can't set tag values for neumann sets" );

    delete[] vals;

    return MB_SUCCESS;
}
// a reverse operation for splitting an gedge at a mesh node
ErrorCode FBEngine::chain_edges( double min_dot )
{
    Range sets[5];
    ErrorCode rval;
    while( 1 )  // break out only if no edges are chained
    {
        rval = _my_geomTopoTool->find_geomsets( sets );
        MBERRORR( rval, "can't get geo sets" );
        // these gentities are "always" current, while the ones in this-> _my_gsets[0:4] are
        // the "originals" before FBEngine modifications
        int nedges = (int)sets[1].size();
        // as long as we have chainable edges, continue;
        bool chain = false;
        for( int i = 0; i < nedges; i++ )
        {
            EntityHandle edge = sets[1][i];
            EntityHandle next_edge;
            bool chainable = false;
            rval           = chain_able_edge( edge, min_dot, next_edge, chainable );
            MBERRORR( rval, "can't determine chain-ability" );
            if( chainable )
            {
                rval = chain_two_edges( edge, next_edge );
                MBERRORR( rval, "can't chain 2 edges" );
                chain = true;
                break;  // interrupt for loop
            }
        }
        if( !chain )
        {
            break;  // break out of while loop
        }
    }
    return MB_SUCCESS;
}

// determine if from the end of edge we can extend with another edge; return also the
//  extension edge (next_edge)
ErrorCode FBEngine::chain_able_edge( EntityHandle edge, double min_dot, EntityHandle& next_edge, bool& chainable )
{
    // get the end, then get all parents of end
    // see if some are the starts of
    chainable = false;
    EntityHandle v1, v2;
    ErrorCode rval = get_vert_edges( edge, v1, v2 );
    MBERRORR( rval, "can't get vertices" );
    if( v1 == v2 ) return MB_SUCCESS;  // it is periodic, can't chain it with another edge!

    // v2 is a set, get its parents, which should be edges
    Range edges;
    rval = _mbImpl->get_parent_meshsets( v2, edges );
    MBERRORR( rval, "can't get parents of vertex set" );
    // get parents of current edge (faces)
    Range faces;
    rval = _mbImpl->get_parent_meshsets( edge, faces );
    MBERRORR( rval, "can't get parents of edge set" );
    // get also the last edge "tangent" at the vertex
    std::vector< EntityHandle > mesh_edges;
    rval = _mbImpl->get_entities_by_type( edge, MBEDGE, mesh_edges );
    MBERRORR( rval, "can't get mesh edges from edge set" );
    EntityHandle lastMeshEdge = mesh_edges[mesh_edges.size() - 1];
    const EntityHandle* conn2 = NULL;
    int len                   = 0;
    rval                      = _mbImpl->get_connectivity( lastMeshEdge, conn2, len );
    MBERRORR( rval, "can't connectivity of last mesh edge" );
    // get the coordinates of last edge
    if( len != 2 ) MBERRORR( MB_FAILURE, "bad number of vertices" );
    CartVect P[2];
    rval = _mbImpl->get_coords( conn2, len, (double*)&P[0] );
    MBERRORR( rval, "Failed to get coordinates" );

    CartVect vec1( P[1] - P[0] );
    vec1.normalize();
    for( Range::iterator edgeIter = edges.begin(); edgeIter != edges.end(); ++edgeIter )
    {
        EntityHandle otherEdge = *edgeIter;
        if( edge == otherEdge ) continue;
        // get faces parents of this edge
        Range faces2;
        rval = _mbImpl->get_parent_meshsets( otherEdge, faces2 );
        MBERRORR( rval, "can't get parents of other edge set" );
        if( faces != faces2 ) continue;
        // now, if the first mesh edge is within given angle, we can go on
        std::vector< EntityHandle > mesh_edges2;
        rval = _mbImpl->get_entities_by_type( otherEdge, MBEDGE, mesh_edges2 );
        MBERRORR( rval, "can't get mesh edges from other edge set" );
        EntityHandle firstMeshEdge = mesh_edges2[0];
        const EntityHandle* conn22;
        int len2;
        rval = _mbImpl->get_connectivity( firstMeshEdge, conn22, len2 );
        MBERRORR( rval, "can't connectivity of first mesh edge" );
        if( len2 != 2 ) MBERRORR( MB_FAILURE, "bad number of vertices" );
        if( conn2[1] != conn22[0] ) continue;  // the mesh edges are not one after the other
        // get the coordinates of first edge

        // CartVect P2[2];
        rval = _mbImpl->get_coords( conn22, len, (double*)&P[0] );
        CartVect vec2( P[1] - P[0] );
        vec2.normalize();
        if( vec1 % vec2 < min_dot ) continue;
        // we found our edge, victory! we can get out
        next_edge = otherEdge;
        chainable = true;
        return MB_SUCCESS;
    }

    return MB_SUCCESS;  // in general, hard to come by chain-able edges
}
ErrorCode FBEngine::chain_two_edges( EntityHandle edge, EntityHandle next_edge )
{
    // the biggest thing is to see the sense tags; or maybe not...
    // they should be correct :)
    // get the vertex sets
    EntityHandle v11, v12, v21, v22;
    ErrorCode rval = get_vert_edges( edge, v11, v12 );
    MBERRORR( rval, "can't get vert sets" );
    rval = get_vert_edges( next_edge, v21, v22 );
    MBERRORR( rval, "can't get vert sets" );
    assert( v12 == v21 );
    std::vector< EntityHandle > mesh_edges;
    rval = MBI->get_entities_by_type( next_edge, MBEDGE, mesh_edges );
    MBERRORR( rval, "can't get mesh edges" );

    rval = _mbImpl->add_entities( edge, &mesh_edges[0], (int)mesh_edges.size() );
    MBERRORR( rval, "can't add new mesh edges" );
    // remove the child - parent relation for second vertex of first edge
    rval = _mbImpl->remove_parent_child( edge, v12 );
    MBERRORR( rval, "can't remove parent - child relation between first edge and middle vertex" );

    if( v22 != v11 )  // the edge would become periodic, do not add again the relationship
    {
        rval = _mbImpl->add_parent_child( edge, v22 );
        MBERRORR( rval, "can't add second vertex to edge " );
    }
    // we can now safely eliminate next_edge
    rval = _mbImpl->remove_parent_child( next_edge, v21 );
    MBERRORR( rval, "can't remove child - parent relation " );

    rval = _mbImpl->remove_parent_child( next_edge, v22 );
    MBERRORR( rval, "can't remove child - parent relation " );

    // remove the next_edge relation to the faces
    Range faces;
    rval = _mbImpl->get_parent_meshsets( next_edge, faces );
    MBERRORR( rval, "can't get parent faces " );

    for( Range::iterator it = faces.begin(); it != faces.end(); ++it )
    {
        EntityHandle ff = *it;
        rval            = _mbImpl->remove_parent_child( ff, next_edge );
        MBERRORR( rval, "can't remove parent-edge rel " );
    }

    rval = _mbImpl->delete_entities( &next_edge, 1 );
    MBERRORR( rval, "can't remove edge set " );

    // delete the vertex set that is idle now (v12 = v21)
    rval = _mbImpl->delete_entities( &v12, 1 );
    MBERRORR( rval, "can't remove edge set " );
    return MB_SUCCESS;
}
ErrorCode FBEngine::get_vert_edges( EntityHandle edge, EntityHandle& v1, EntityHandle& v2 )
{
    // need to decide first or second vertex
    // important for moab

    Range children;
    // EntityHandle v1, v2;
    ErrorCode rval = _mbImpl->get_child_meshsets( edge, children );
    MBERRORR( rval, "can't get child meshsets" );
    if( children.size() == 1 )
    {
        // this is periodic edge, get out early
        v1 = children[0];
        v2 = v1;
        return MB_SUCCESS;
    }
    else if( children.size() > 2 )
        MBERRORR( MB_FAILURE, "too many vertices in one edge" );
    // edge: get one vertex as part of the vertex set
    Range entities;
    rval = MBI->get_entities_by_type( children[0], MBVERTEX, entities );
    MBERRORR( rval, "can't get entities from vertex set" );
    if( entities.size() < 1 ) MBERRORR( MB_FAILURE, "no mesh nodes in vertex set" );
    EntityHandle node0 = entities[0];  // the first vertex
    entities.clear();

    // now get the edges, and get the first node and the last node in sequence of edges
    // the order is important...
    // these are ordered sets !!
    std::vector< EntityHandle > ents;
    rval = MBI->get_entities_by_type( edge, MBEDGE, ents );
    MBERRORR( rval, "can't get mesh edges" );
    if( ents.size() < 1 ) MBERRORR( MB_FAILURE, "no mesh edges in edge set" );

    const EntityHandle* conn = NULL;
    int len;
    rval = MBI->get_connectivity( ents[0], conn, len );
    MBERRORR( rval, "can't connectivity of first mesh edge" );

    if( conn[0] == node0 )
    {
        v1 = children[0];
        v2 = children[1];
    }
    else  // the other way around, although we should check (we are paranoid)
    {
        v2 = children[0];
        v1 = children[1];
    }

    return MB_SUCCESS;
}
}  // namespace moab