seg.cpp

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/*
 * This program source code file is part of KiCad, a free EDA CAD application.
 *
 * Copyright (C) 2013 CERN
 * @author Tomasz Wlostowski <tomasz.wlostowski@cern.ch>
 *
 * This program is free software; you can redistribute it and/or
 * modify it under the terms of the GNU General Public License
 * as published by the Free Software Foundation; either version 2
 * of the License, or (at your option) any later version.
 *
 * This program 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 General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program; if not, you may find one here:
 * http://www.gnu.org/licenses/old-licenses/gpl-2.0.html
 * or you may search the http://www.gnu.org website for the version 2 license,
 * or you may write to the Free Software Foundation, Inc.,
 * 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301, USA
 */

#include <algorithm>        // for min
#include <geometry/seg.h>
#include <math/util.h>      // for rescale
#include <math/vector2d.h>  // for VECTOR2I, VECTOR2

template <typename T>
int sgn( T aVal )
{
    return ( T( 0 ) < aVal ) - ( aVal < T( 0 ) );
}


SEG::ecoord SEG::SquaredDistance( const SEG& aSeg ) const
{
    // fixme: rather inefficient....
    if( Intersect( aSeg ) )
        return 0;

    const VECTOR2I pts[4] =
    {
        aSeg.NearestPoint( A ) - A,
        aSeg.NearestPoint( B ) - B,
        NearestPoint( aSeg.A ) - aSeg.A,
        NearestPoint( aSeg.B ) - aSeg.B
    };

    ecoord m = VECTOR2I::ECOORD_MAX;
  
    for( int i = 0; i < 4; i++ )
    {
        m = std::min( m, pts[i].SquaredEuclideanNorm() );
    }

    return m;
}


const VECTOR2I SEG::NearestPoint( const SEG& aSeg ) const
{
    if( OPT_VECTOR2I p = Intersect( aSeg ) )
        return *p;

    const VECTOR2I pts_origin[4] =
    {
            aSeg.NearestPoint( A ),
            aSeg.NearestPoint( B ),
            NearestPoint( aSeg.A ),
            NearestPoint( aSeg.B )
    };


    const VECTOR2I* pts_out[4] =
    {
            &A,
            &B,
            &pts_origin[2],
            &pts_origin[3]
    };

    const ecoord pts_dist[4] =
    {
            ( pts_origin[0] - A ).SquaredEuclideanNorm(),
            ( pts_origin[1] - B ).SquaredEuclideanNorm(),
            ( pts_origin[2] - aSeg.A ).SquaredEuclideanNorm(),
            ( pts_origin[3] - aSeg.B ).SquaredEuclideanNorm()
    };

    int min_i = 0;
 
    for( int i = 0; i < 4; i++ )
    {
        if( pts_dist[i] < pts_dist[min_i] )
            min_i = i;
    }

    return *pts_out[min_i];
}


OPT_VECTOR2I SEG::Intersect( const SEG& aSeg, bool aIgnoreEndpoints, bool aLines ) const
{
    const VECTOR2I  e( B - A );
    const VECTOR2I  f( aSeg.B - aSeg.A );
    const VECTOR2I  ac( aSeg.A - A );

    ecoord d = f.Cross( e );
    ecoord p = f.Cross( ac );
    ecoord q = e.Cross( ac );

    if( d == 0 )
        return OPT_VECTOR2I();

    if( !aLines && d > 0 && ( q < 0 || q > d || p < 0 || p > d ) )
        return OPT_VECTOR2I();

    if( !aLines && d < 0 && ( q < d || p < d || p > 0 || q > 0 ) )
        return OPT_VECTOR2I();

    if( !aLines && aIgnoreEndpoints && ( q == 0 || q == d ) && ( p == 0 || p == d ) )
        return OPT_VECTOR2I();

    VECTOR2I ip( aSeg.A.x + rescale( q, (ecoord) f.x, d ),
                 aSeg.A.y + rescale( q, (ecoord) f.y, d ) );

     return ip;
}


bool SEG::ccw( const VECTOR2I& aA, const VECTOR2I& aB, const VECTOR2I& aC ) const
{
    return (ecoord) ( aC.y - aA.y ) * ( aB.x - aA.x ) > (ecoord) ( aB.y - aA.y ) * ( aC.x - aA.x );
}


bool SEG::Collide( const SEG& aSeg, int aClearance, int* aActual ) const
{
    // check for intersection
    // fixme: move to a method
    if( ccw( A, aSeg.A, aSeg.B ) != ccw( B, aSeg.A, aSeg.B ) &&
            ccw( A, B, aSeg.A ) != ccw( A, B, aSeg.B ) )
    {
        if( aActual )
            *aActual = 0;

        return true;
    }

    ecoord dist_sq = VECTOR2I::ECOORD_MAX;

    dist_sq = std::min( dist_sq, SquaredDistance( aSeg.A ) );
    dist_sq = std::min( dist_sq, SquaredDistance( aSeg.B ) );
    dist_sq = std::min( dist_sq, aSeg.SquaredDistance( A ) );
    dist_sq = std::min( dist_sq, aSeg.SquaredDistance( B ) );

    if( dist_sq == 0 || dist_sq < (ecoord) aClearance * aClearance )
    {
        if( aActual )
            *aActual = sqrt( dist_sq );

        return true;
    }

    return false;
}


bool SEG::Contains( const VECTOR2I& aP ) const
{
    return SquaredDistance( aP ) < 1;       // 1 * 1 to be pedantic
}