BoundBox.cpp

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#include "moab/Interface.hpp"
#include "moab/BoundBox.hpp"

// this is used for spherical elements, bounding box needs to be updated due to curvature
#include "moab/IntxMesh/IntxUtils.hpp"

namespace moab
{
ErrorCode BoundBox::update( Interface& iface, const Range& elems, bool spherical, double radius )
{
    ErrorCode rval;
    bMin = CartVect( HUGE_VAL );
    bMax = CartVect( -HUGE_VAL );

    CartVect coords;
    EntityHandle const *conn = NULL, *conn2 = NULL;
    int len = 0, len2 = 0;
    Range::const_iterator i;
    CartVect coordverts[27];  // maximum nodes per element supported by MOAB

    // vertices
    const Range::const_iterator elem_begin = elems.lower_bound( MBEDGE );
    for( i = elems.begin(); i != elem_begin; ++i )
    {
        rval = iface.get_coords( &*i, 1, coords.array() );
        if( MB_SUCCESS != rval ) return rval;
        update_min( coords.array() );
        update_max( coords.array() );
    }

    // elements with vertex-handle connectivity list
    const Range::const_iterator poly_begin = elems.lower_bound( MBPOLYHEDRON, elem_begin );
    std::vector< EntityHandle > dum_vector;
    for( i = elem_begin; i != poly_begin; ++i )
    {
        rval = iface.get_connectivity( *i, conn, len, true, &dum_vector );
        if( MB_SUCCESS != rval ) return rval;

        rval = iface.get_coords( conn, len, &( coordverts[0][0] ) );
        if( MB_SUCCESS != rval ) return rval;
        for( int j = 0; j < len; ++j )
        {
            update_min( coordverts[j].array() );
            update_max( coordverts[j].array() );
        }
        // if spherical, use gnomonic projection to improve the computed box
        // it is used now for coupling only
        if( spherical ) update_box_spherical_elem( coordverts, len, radius );
    }

    // polyhedra
    const Range::const_iterator set_begin = elems.lower_bound( MBENTITYSET, poly_begin );
    for( i = poly_begin; i != set_begin; ++i )
    {
        rval = iface.get_connectivity( *i, conn, len, true );
        if( MB_SUCCESS != rval ) return rval;

        for( int j = 0; j < len; ++j )
        {
            rval = iface.get_connectivity( conn[j], conn2, len2 );
            if( MB_SUCCESS != rval ) return rval;
            rval = iface.get_coords( conn2, len2, &( coordverts[0][0] ) );
            if( MB_SUCCESS != rval ) return rval;
            for( int k = 0; k < len2; ++k )
            {
                update_min( coordverts[k].array() );
                update_max( coordverts[k].array() );
            }
        }
    }

    // sets
    BoundBox box;
    for( i = set_begin; i != elems.end(); ++i )
    {
        Range tmp_elems;
        rval = iface.get_entities_by_handle( *i, tmp_elems );
        if( MB_SUCCESS != rval ) return rval;
        rval = box.update( iface, tmp_elems, spherical, radius );
        if( MB_SUCCESS != rval ) return rval;

        update( box );
    }

    return MB_SUCCESS;
}
void BoundBox::update_box_spherical_elem( const CartVect* verts, int len, double R )
{
    // decide first the gnomonic plane, based on first coordinate
    int plane = -1;
    CartVect pos;
    IntxUtils::decide_gnomonic_plane( verts[0], plane );
    double in_plane_positions[20];  // at most polygons with 10 edges; do we need to revise this?
    for( int i = 0; i < len && i < 10; i++ )
        IntxUtils::gnomonic_projection( verts[i], R, plane, in_plane_positions[2 * i], in_plane_positions[2 * i + 1] );
    // look for points on the intersection between edges in gnomonic plane and coordinate axes
    // if yes, reverse projection of intx point, and update box
    double oriented_area2 = 0;
    // if oriented area is != zero, it means the origin is inside the polygon, so we need to upgrade
    // the box with the origin, so we do not miss anything (the top of the dome)
    for( int i = 0; i < len; i++ )
    {
        int i1 = ( i + 1 ) % len;  // next vertex in polygon
        // check intx with x axis
        double ax = in_plane_positions[2 * i], ay = in_plane_positions[2 * i + 1];
        double bx = in_plane_positions[2 * i1], by = in_plane_positions[2 * i1 + 1];
        if( ay * by < 0 )  // it intersects with x axis
        {
            double alfa  = ay / ( ay - by );
            double xintx = ax + alfa * ( bx - ax );
            IntxUtils::reverse_gnomonic_projection( xintx, 0, R, plane, pos );
            update_min( pos.array() );
            update_max( pos.array() );
        }
        if( ax * bx < 0 )  // it intersects with y axis
        {
            double alfa  = ax / ( ax - bx );
            double yintx = ay + alfa * ( by - ay );
            IntxUtils::reverse_gnomonic_projection( 0, yintx, R, plane, pos );
            update_min( pos.array() );
            update_max( pos.array() );
        }
        oriented_area2 += ( ax * by - ay * bx );
    }
    if( fabs( oriented_area2 ) > R * R * 1.e-6 )  // origin is in the interior, add the center
    {
        IntxUtils::reverse_gnomonic_projection( 0, 0, R, plane, pos );
        update_min( pos.array() );
        update_max( pos.array() );
    }
}
}  // namespace moab