DomainUtil.cpp

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

    Copyright 2010 Sandia National Laboratories.  Developed at the
    University of Wisconsin--Madison under SNL contract number
    624796.  The U.S. Government and the University of Wisconsin
    retain certain rights to this software.

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

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

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

    (2010) kraftche@cae.wisc.edu

  ***************************************************************** */

/** \file DomainUtil.cpp
 *  \brief
 *  \author Jason Kraftcheck
 */

#include "Mesquite.hpp"
#include "DomainUtil.hpp"
#include "MeshInterface.hpp"
#include "MsqVertex.hpp"
#include "MsqError.hpp"

namespace MBMesquite
{
namespace DomainUtil
{

    void bounding_box( const MsqVertex* coords, size_t num_coords, Vector3D& min, Vector3D& max )
    {
        min = max = coords[0];
        for( size_t i = 1; i < num_coords; ++i )
        {
            for( int j = 0; j < 3; ++j )
            {
                if( coords[i][j] < min[j] ) min[j] = coords[i][j];
                if( coords[i][j] > max[j] ) max[j] = coords[i][j];
            }
        }
    }

    double max_box_extent( const MsqVertex* vertex_array, size_t num_vertices )
    {
        Vector3D min, max;
        bounding_box( vertex_array, num_vertices, min, max );
        max -= min;
        return ( max[0] >= max[1] && max[0] >= max[2] ) ? max[0] : ( max[1] >= max[2] ) ? max[1] : max[2];
    }

    void get_fixed_vertices( Mesh* mesh,
                             const Mesh::VertexHandle* verts,
                             size_t num_verts,
                             std::vector< Mesh::VertexHandle >& fixed_verts,
                             MsqError& err )
    {
        std::vector< bool > fixed( num_verts );
        mesh->vertices_get_fixed_flag( verts, fixed, num_verts, err );MSQ_ERRRTN( err );
        for( size_t i = 0; i < num_verts; ++i )
            if( fixed[i] ) fixed_verts.push_back( verts[i] );
    }

    bool non_colinear_vertices( const MsqVertex* verts, size_t num_verts, Vector3D coords_out[3], double epsilon )
    {
        // This function will attempt to find trhee non-colinear
        // vertices from the input list.  Further, it will attempt
        // to select three such vertices that are relatively far
        // apart so as to minimize rounding error in any calculation
        // using the results of this function.

        // Non-colinear, by definition, must be at least trhee unique points.
        if( num_verts < 3 ) return false;

        // Begin with the first input vertex
        size_t first_idx = 0;

        // Choose the vertex furthest from the initial one
        size_t second_idx = 1;
        double dist_sqr   = ( verts[first_idx] - verts[second_idx] ).length_squared();
        for( size_t i = 2; i < num_verts; ++i )
        {
            double ds = ( verts[second_idx] - verts[i] ).length_squared();
            if( ds > dist_sqr )
            {
                dist_sqr   = ds;
                second_idx = i;
            }
        }
        // fail if all vertices are coincident
        if( dist_sqr <= epsilon * epsilon ) return false;

        // re-select the first vertex as the one furthest from the second
        for( size_t i = 1; i < num_verts; ++i )
        {
            double ds = ( verts[second_idx] - verts[i] ).length_squared();
            if( ds > dist_sqr )
            {
                dist_sqr  = ds;
                first_idx = i;
            }
        }

        // select the third vertex as the one furthest from the line formed
        // by the first two vertices
        Vector3D b       = verts[first_idx];
        Vector3D m       = verts[second_idx] - b;
        Vector3D mx      = m * ( 1.0 / m.length_squared() );
        dist_sqr         = -1.0;
        size_t third_idx = 0;
        for( size_t i = 0; i < num_verts; ++i )
        {
            double t  = mx % ( verts[i] - b );
            double ds = ( ( b + t * m ) - verts[i] ).length_squared();
            if( ds > dist_sqr )
            {
                third_idx = i;
                dist_sqr  = ds;
            }
        }
        // fail if all vertices are colinear
        if( dist_sqr <= epsilon * epsilon ) return false;

        coords_out[0] = verts[first_idx];
        coords_out[1] = verts[second_idx];
        coords_out[2] = verts[third_idx];
        return true;
    }

    bool non_coplanar_vertices( const MsqVertex* verts, size_t num_verts, Vector3D coords_out[4], double epsilon )
    {
        // This function will attempt to find four non-coplanar
        // vertices from the input list.  Further, it will attempt
        // to select four such vertices that are relatively far
        // apart so as to minimize rounding error in any calculation
        // using the results of this function.

        // Non-coplanar, by definition, must be at least four unique points.
        if( num_verts < 4 ) return false;

        // Get three non-colinear vertices
        if( !non_colinear_vertices( verts, num_verts, coords_out, epsilon ) ) return false;

        // The plane of the first three vertices:
        Vector3D norm = ( coords_out[1] - coords_out[0] ) * ( coords_out[2] - coords_out[0] );
        norm /= norm.length();
        double d = -( norm % coords_out[0] );

        // Search for the fourth vertex that is furthest from the plane
        // of the first three
        double dist = -1.0;
        for( size_t i = 0; i < num_verts; ++i )
        {
            double disti = fabs( norm % verts[i] + d );
            if( disti > dist )
            {
                dist          = disti;
                coords_out[3] = verts[i];
            }
        }

        // fail if all vertices are colinear
        return ( dist > epsilon );
    }

}  // namespace DomainUtil
}  // namespace MBMesquite