shape_line_chain.cpp

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/*
 * This program source code file is part of KiCad, a free EDA CAD application.
 *
 * Copyright (C) 2013-2017 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>
#include <limits.h>          // for INT_MAX
#include <math.h>            // for hypot
#include <string>            // for basic_string

#include <clipper.hpp>
#include <geometry/seg.h>    // for SEG, OPT_VECTOR2I
#include <geometry/shape_line_chain.h>
#include <math/box2.h>       // for BOX2I
#include <math/util.h>  // for rescale
#include <math/vector2d.h>   // for VECTOR2, VECTOR2I

class SHAPE;

SHAPE_LINE_CHAIN::SHAPE_LINE_CHAIN( const std::vector<int>& aV)
    : SHAPE_LINE_CHAIN_BASE( SH_LINE_CHAIN ), m_closed( false ), m_width( 0 )
{
    for(size_t i = 0; i < aV.size(); i+= 2 )
    {
        Append( aV[i], aV[i+1] );
    }
}

ClipperLib::Path SHAPE_LINE_CHAIN::convertToClipper( bool aRequiredOrientation ) const
{
    ClipperLib::Path c_path;

    for( int i = 0; i < PointCount(); i++ )
    {
        const VECTOR2I& vertex = CPoint( i );
        c_path.push_back( ClipperLib::IntPoint( vertex.x, vertex.y ) );
    }

    if( Orientation( c_path ) != aRequiredOrientation )
        ReversePath( c_path );

    return c_path;
}


//TODO(SH): Adjust this into two functions: one to convert and one to split the arc into two arcs
void SHAPE_LINE_CHAIN::convertArc( ssize_t aArcIndex )
{
    if( aArcIndex < 0 )
        aArcIndex += m_arcs.size();

    if( aArcIndex >= static_cast<ssize_t>( m_arcs.size() ) )
        return;

    // Clear the shapes references
    for( auto& sh : m_shapes )
    {
        if( sh == aArcIndex )
            sh = SHAPE_IS_PT;

        if( sh > aArcIndex )
            --sh;
    }

    m_arcs.erase( m_arcs.begin() + aArcIndex );
}


bool SHAPE_LINE_CHAIN_BASE::Collide( const VECTOR2I& aP, int aClearance, int* aActual,
                                     VECTOR2I* aLocation ) const
{
    if( IsClosed() && PointInside( aP, aClearance ) )
    {
        if( aLocation )
            *aLocation = aP;

        if( aActual )
            *aActual = 0;

        return true;
    }

    SEG::ecoord closest_dist_sq = VECTOR2I::ECOORD_MAX;
    SEG::ecoord clearance_sq = SEG::Square( aClearance );
    VECTOR2I nearest;

    for( size_t i = 0; i < GetSegmentCount(); i++ )
    {
        const SEG& s = GetSegment( i );
        VECTOR2I pn = s.NearestPoint( aP );
        SEG::ecoord dist_sq = ( pn - aP ).SquaredEuclideanNorm();

        if( dist_sq < closest_dist_sq )
        {
            nearest = pn;
            closest_dist_sq = dist_sq;

            if( closest_dist_sq == 0 )
                break;

            // If we're not looking for aActual then any collision will do
            if( closest_dist_sq < clearance_sq && !aActual )
                break;
        }
    }

    if( closest_dist_sq == 0 || closest_dist_sq < clearance_sq )
    {
        if( aLocation )
            *aLocation = nearest;

        if( aActual )
            *aActual = sqrt( closest_dist_sq );

        return true;
    }

    return false;
}


void SHAPE_LINE_CHAIN::Rotate( double aAngle, const VECTOR2I& aCenter )
{
    for( auto& pt : m_points )
    {
        pt -= aCenter;
        pt = pt.Rotate( aAngle );
        pt += aCenter;
    }

    for( auto& arc : m_arcs )
        arc.Rotate( aAngle, aCenter );
}


bool SHAPE_LINE_CHAIN_BASE::Collide( const SEG& aSeg, int aClearance, int* aActual,
                                     VECTOR2I* aLocation ) const
{
    if( IsClosed() && PointInside( aSeg.A ) )
    {
        if( aLocation )
            *aLocation = aSeg.A;

        if( aActual )
            *aActual = 0;

        return true;
    }

    SEG::ecoord closest_dist_sq = VECTOR2I::ECOORD_MAX;
    SEG::ecoord clearance_sq = SEG::Square( aClearance );
    VECTOR2I nearest;

    for( size_t i = 0; i < GetSegmentCount(); i++ )
    {
        const SEG& s = GetSegment( i );
        SEG::ecoord dist_sq =s.SquaredDistance( aSeg );

        if( dist_sq < closest_dist_sq )
        {
            if( aLocation )
                nearest = s.NearestPoint( aSeg );

            closest_dist_sq = dist_sq;

            if( closest_dist_sq == 0)
                break;

            // If we're not looking for aActual then any collision will do
            if( closest_dist_sq < clearance_sq && !aActual )
                break;
        }
    }

    if( closest_dist_sq == 0 || closest_dist_sq < clearance_sq )
    {
        if( aLocation )
            *aLocation = nearest;

        if( aActual )
            *aActual = sqrt( closest_dist_sq );

        return true;
    }

    return false;
}


const SHAPE_LINE_CHAIN SHAPE_LINE_CHAIN::Reverse() const
{
    SHAPE_LINE_CHAIN a( *this );

    reverse( a.m_points.begin(), a.m_points.end() );
    reverse( a.m_shapes.begin(), a.m_shapes.end() );
    reverse( a.m_arcs.begin(), a.m_arcs.end() );

    for( auto& sh : a.m_shapes )
    {
        if( sh != SHAPE_IS_PT )
            sh = a.m_arcs.size() - sh - 1;
    }

    for( SHAPE_ARC& arc : a.m_arcs )
        arc.Reverse();

    a.m_closed = m_closed;

    return a;
}


long long int SHAPE_LINE_CHAIN::Length() const
{
    long long int l = 0;

    for( int i = 0; i < SegmentCount(); i++ )
    {
        // Only include segments that aren't part of arc shapes
        if( m_shapes[i] == SHAPE_IS_PT || m_shapes[i + 1] == SHAPE_IS_PT ||
            ( m_shapes[i] != m_shapes[i + 1] ) )
        {
            l += CSegment( i ).Length();
        }
    }

    for( int i = 0; i < ArcCount(); i++ )
        l += CArcs()[i].GetLength();

    return l;
}


void SHAPE_LINE_CHAIN::Mirror( bool aX, bool aY, const VECTOR2I& aRef )
{
    for( auto& pt : m_points )
    {
        if( aX )
            pt.x = -pt.x + 2 * aRef.x;

        if( aY )
            pt.y = -pt.y + 2 * aRef.y;
    }

    for( auto& arc : m_arcs )
        arc.Mirror( aX, aY, aRef );
}


void SHAPE_LINE_CHAIN::Mirror( const SEG& axis )
{
    for( auto& pt : m_points )
        pt = axis.ReflectPoint( pt );

    for( auto& arc : m_arcs )
        arc.Mirror( axis );
}


void SHAPE_LINE_CHAIN::Replace( int aStartIndex, int aEndIndex, const VECTOR2I& aP )
{
    if( aEndIndex < 0 )
        aEndIndex += PointCount();

    if( aStartIndex < 0 )
        aStartIndex += PointCount();

    aEndIndex = std::min( aEndIndex, PointCount() - 1 );

    // N.B. This works because convertArc changes m_shapes on the first run
    for( int ind = aStartIndex; ind <= aEndIndex; ind++ )
    {
        if( m_shapes[ind] != SHAPE_IS_PT )
            convertArc( ind );
    }

    if( aStartIndex == aEndIndex )
        m_points[aStartIndex] = aP;
    else
    {
        m_points.erase( m_points.begin() + aStartIndex + 1, m_points.begin() + aEndIndex + 1 );
        m_points[aStartIndex] = aP;

        m_shapes.erase( m_shapes.begin() + aStartIndex + 1, m_shapes.begin() + aEndIndex + 1 );
    }

    assert( m_shapes.size() == m_points.size() );
}


void SHAPE_LINE_CHAIN::Replace( int aStartIndex, int aEndIndex, const SHAPE_LINE_CHAIN& aLine )
{
    if( aEndIndex < 0 )
        aEndIndex += PointCount();

    if( aStartIndex < 0 )
        aStartIndex += PointCount();

    // We only process lines in order in this house
    wxASSERT( aStartIndex <= aEndIndex );
    wxASSERT( aEndIndex < m_points.size() );

    SHAPE_LINE_CHAIN newLine = aLine;

    // It's possible that the start or end lands on the end of an arc.  If so, we'd better have a
    // replacement line that matches up to the same coordinates, as we can't break the arc(s).
    ssize_t startShape = m_shapes[aStartIndex];
    ssize_t endShape   = m_shapes[aEndIndex];

    if( startShape >= 0 )
    {
        wxASSERT( !newLine.PointCount() ||
                  ( newLine.m_points.front() == m_points[aStartIndex] &&
                  aStartIndex < m_points.size() - 1 ) );
        aStartIndex++;
        newLine.Remove( 0 );
    }

    if( endShape >= 0 )
    {
        wxASSERT( !newLine.PointCount() ||
                  ( newLine.m_points.back() == m_points[aEndIndex] && aEndIndex > 0 ) );
        aEndIndex--;
        newLine.Remove( -1 );
    }

    Remove( aStartIndex, aEndIndex );

    if( !aLine.PointCount() )
        return;

    // The total new arcs index is added to the new arc indices
    size_t               prev_arc_count = m_arcs.size();
    std::vector<ssize_t> new_shapes     = newLine.m_shapes;

    for( ssize_t& shape : new_shapes )
    {
        if( shape >= 0 )
            shape += prev_arc_count;
    }

    m_shapes.insert( m_shapes.begin() + aStartIndex, new_shapes.begin(), new_shapes.end() );
    m_points.insert( m_points.begin() + aStartIndex, newLine.m_points.begin(),
                     newLine.m_points.end() );
    m_arcs.insert( m_arcs.end(), newLine.m_arcs.begin(), newLine.m_arcs.end() );

    assert( m_shapes.size() == m_points.size() );
}


void SHAPE_LINE_CHAIN::Remove( int aStartIndex, int aEndIndex )
{
    assert( m_shapes.size() == m_points.size() );

    if( aEndIndex < 0 )
        aEndIndex += PointCount();

    if( aStartIndex < 0 )
        aStartIndex += PointCount();

    if( aStartIndex >= PointCount() )
        return;

    aEndIndex = std::min( aEndIndex, PointCount() );
    std::set<size_t> extra_arcs;

    // Remove any overlapping arcs in the point range
    for( int i = aStartIndex; i < aEndIndex; i++ )
    {
        if( m_shapes[i] != SHAPE_IS_PT )
            extra_arcs.insert( m_shapes[i] );
    }

    for( auto arc : extra_arcs )
        convertArc( arc );

    m_shapes.erase( m_shapes.begin() + aStartIndex, m_shapes.begin() + aEndIndex + 1 );
    m_points.erase( m_points.begin() + aStartIndex, m_points.begin() + aEndIndex + 1 );
    assert( m_shapes.size() == m_points.size() );
}


int SHAPE_LINE_CHAIN::Distance( const VECTOR2I& aP, bool aOutlineOnly ) const
{
    return sqrt( SquaredDistance( aP, aOutlineOnly ) );
}


SEG::ecoord SHAPE_LINE_CHAIN_BASE::SquaredDistance( const VECTOR2I& aP, bool aOutlineOnly ) const
{
    ecoord d = VECTOR2I::ECOORD_MAX;

    if( IsClosed() && PointInside( aP ) && !aOutlineOnly )
        return 0;

    for( size_t s = 0; s < GetSegmentCount(); s++ )
        d = std::min( d, GetSegment( s ).SquaredDistance( aP ) );

    return d;
}


int SHAPE_LINE_CHAIN::Split( const VECTOR2I& aP )
{
    int ii = -1;
    int min_dist = 2;

    int found_index = Find( aP );

    for( int s = 0; s < SegmentCount(); s++ )
    {
        const SEG seg = CSegment( s );
        int dist = seg.Distance( aP );

        // make sure we are not producing a 'slightly concave' primitive. This might happen
        // if aP lies very close to one of already existing points.
        if( dist < min_dist && seg.A != aP && seg.B != aP )
        {
            min_dist = dist;
            if( found_index < 0 )
                ii = s;
            else if( s < found_index )
                ii = s;
        }
    }

    if( ii < 0 )
        ii = found_index;

    if( ii >= 0 )
    {
        // Are we splitting at the beginning of an arc?  If so, let's split right before so that
        // the shape is preserved
        if( ii < PointCount() - 1 && m_shapes[ii] >= 0 && m_shapes[ii] == m_shapes[ii + 1] )
            ii--;

        m_points.insert( m_points.begin() + ( ii + 1 ), aP );
        m_shapes.insert( m_shapes.begin() + ( ii + 1 ), ssize_t( SHAPE_IS_PT ) );

        return ii + 1;
    }

    return -1;
}


int SHAPE_LINE_CHAIN::Find( const VECTOR2I& aP ) const
{
    for( int s = 0; s < PointCount(); s++ )
        if( CPoint( s ) == aP )
            return s;

    return -1;
}


int SHAPE_LINE_CHAIN::FindSegment( const VECTOR2I& aP ) const
{
    for( int s = 0; s < SegmentCount(); s++ )
        if( CSegment( s ).Distance( aP ) <= 1 )
            return s;

    return -1;
}


int SHAPE_LINE_CHAIN::ShapeCount() const
{
    if( m_points.empty() )
        return 0;

    int numPoints = static_cast<int>( m_shapes.size() );
    int numShapes = 0;
    int arcIdx    = -1;

    for( int i = 0; i < m_points.size() - 1; i++ )
    {
        if( m_shapes[i] == SHAPE_IS_PT )
        {
            numShapes++;
        }
        else
        {
            arcIdx = m_shapes[i];
            numShapes++;

            // Now skip the rest of the arc
            while( i < numPoints && m_shapes[i] == arcIdx )
                i++;

            // Add the "hidden" segment at the end of the arc, if it exists
            if( i < numPoints &&
                m_points[i] != m_points[i - 1] )
            {
                numShapes++;
            }

            i--;
        }
    }

    return numShapes;
}


int SHAPE_LINE_CHAIN::NextShape( int aPointIndex, bool aForwards ) const
{
    if( aPointIndex < 0 )
        aPointIndex += PointCount();

    // First or last point?
    if( ( aForwards && aPointIndex == PointCount() - 1 ) ||
        ( !aForwards && aPointIndex == 0 ) )
    {
        return -1;
    }

    int delta = aForwards ? 1 : -1;

    if( m_shapes[aPointIndex] == SHAPE_IS_PT )
        return aPointIndex + delta;

    int arcIndex = m_shapes[aPointIndex];
    int arcStart = aPointIndex;

    while( aPointIndex < static_cast<int>( m_shapes.size() ) && m_shapes[aPointIndex] == arcIndex )
        aPointIndex += delta;

    // We want the last vertex of the arc if the initial point was the start of one
    // Well-formed arcs should generate more than one point to travel above
    if( aPointIndex - arcStart > 1 )
        aPointIndex -= delta;

    return aPointIndex;
}


void SHAPE_LINE_CHAIN::RemoveShape( int aPointIndex )
{
    if( aPointIndex < 0 )
        aPointIndex += PointCount();

    if( m_shapes[aPointIndex] == SHAPE_IS_PT )
    {
        Remove( aPointIndex );
        return;
    }

    int start  = aPointIndex;
    int end    = aPointIndex;
    int arcIdx = m_shapes[aPointIndex];

    while( start >= 0 && m_shapes[start] == arcIdx )
        start--;

    while( end < static_cast<int>( m_shapes.size() ) - 1 && m_shapes[end] == arcIdx )
        end++;

    Remove( start, end );
}


const SHAPE_LINE_CHAIN SHAPE_LINE_CHAIN::Slice( int aStartIndex, int aEndIndex ) const
{
    SHAPE_LINE_CHAIN rv;

    if( aEndIndex < 0 )
        aEndIndex += PointCount();

    if( aStartIndex < 0 )
        aStartIndex += PointCount();

    int numPoints = static_cast<int>( m_points.size() );

    for( int i = aStartIndex; i <= aEndIndex && i < numPoints; i++ )
    {
        if( m_shapes[i] != SHAPE_IS_PT )
        {
            int  arcIdx   = m_shapes[i];
            bool wholeArc = true;
            int  arcStart = i;

            if( i > 0 && m_shapes[i - 1] >= 0 && m_shapes[i - 1] != arcIdx )
                wholeArc = false;

            while( i < numPoints && m_shapes[i] == arcIdx )
                i++;

            i--;

            if( i > aEndIndex )
                wholeArc = false;

            if( wholeArc )
            {
                rv.Append( m_arcs[arcIdx] );
            }
            else
            {
                rv.Append( m_points[arcStart] );
                i = arcStart;
            }
        }
        else
        {
            rv.Append( m_points[i] );
        }
    }

    return rv;
}


void SHAPE_LINE_CHAIN::Append( const SHAPE_LINE_CHAIN& aOtherLine )
{
    assert( m_shapes.size() == m_points.size() );

    if( aOtherLine.PointCount() == 0 )
        return;

    else if( PointCount() == 0 || aOtherLine.CPoint( 0 ) != CPoint( -1 ) )
    {
        const VECTOR2I p = aOtherLine.CPoint( 0 );
        m_points.push_back( p );
        m_shapes.push_back( aOtherLine.CShapes()[0] );
        m_bbox.Merge( p );
    }

    size_t num_arcs = m_arcs.size();
    m_arcs.insert( m_arcs.end(), aOtherLine.m_arcs.begin(), aOtherLine.m_arcs.end() );

    for( int i = 1; i < aOtherLine.PointCount(); i++ )
    {
        const VECTOR2I p = aOtherLine.CPoint( i );
        m_points.push_back( p );

        ssize_t arcIndex = aOtherLine.ArcIndex( i );

        if( arcIndex != ssize_t( SHAPE_IS_PT ) )
            m_shapes.push_back( num_arcs + arcIndex );
        else
            m_shapes.push_back( ssize_t( SHAPE_IS_PT ) );

        m_bbox.Merge( p );
    }

    assert( m_shapes.size() == m_points.size() );
}


void SHAPE_LINE_CHAIN::Append( const SHAPE_ARC& aArc )
{
    auto& chain = aArc.ConvertToPolyline();

    for( auto& pt : chain.CPoints() )
    {
        m_points.push_back( pt );
        m_shapes.push_back( m_arcs.size() );
    }

    m_arcs.push_back( aArc );

    assert( m_shapes.size() == m_points.size() );
}


void SHAPE_LINE_CHAIN::Insert( size_t aVertex, const VECTOR2I& aP )
{
    if( aVertex < m_points.size() && m_shapes[aVertex] != SHAPE_IS_PT )
        convertArc( aVertex );

    m_points.insert( m_points.begin() + aVertex, aP );
    m_shapes.insert( m_shapes.begin() + aVertex, ssize_t( SHAPE_IS_PT ) );

    assert( m_shapes.size() == m_points.size() );
}


void SHAPE_LINE_CHAIN::Insert( size_t aVertex, const SHAPE_ARC& aArc )
{
    if( m_shapes[aVertex] != SHAPE_IS_PT )
        convertArc( aVertex );

    size_t arc_pos = m_arcs.size();

    for( auto arc_it = m_shapes.rbegin() ;
              arc_it != m_shapes.rend() + aVertex;
              arc_it++ )
    {
        if( *arc_it != SHAPE_IS_PT )
            arc_pos = ( *arc_it )++;
    }

    m_arcs.insert( m_arcs.begin() + arc_pos, aArc );

    auto& chain = aArc.ConvertToPolyline();
    m_points.insert( m_points.begin() + aVertex,
            chain.CPoints().begin(), chain.CPoints().end() );

    std::vector<size_t> new_points( chain.PointCount(), arc_pos );
    m_shapes.insert( m_shapes.begin() + aVertex, new_points.begin(), new_points.end() );
    assert( m_shapes.size() == m_points.size() );
}


struct compareOriginDistance
{
    compareOriginDistance( const VECTOR2I& aOrigin ) :
        m_origin( aOrigin ) {};

    bool operator()( const SHAPE_LINE_CHAIN::INTERSECTION& aA,
                     const SHAPE_LINE_CHAIN::INTERSECTION& aB ) const
    {
        return ( m_origin - aA.p ).EuclideanNorm() < ( m_origin - aB.p ).EuclideanNorm();
    }

    VECTOR2I m_origin;
};


int SHAPE_LINE_CHAIN::Intersect( const SEG& aSeg, INTERSECTIONS& aIp ) const
{
    for( int s = 0; s < SegmentCount(); s++ )
    {
        OPT_VECTOR2I p = CSegment( s ).Intersect( aSeg );

        if( p )
        {
            INTERSECTION is;
            is.our = CSegment( s );
            is.their = aSeg;
            is.p = *p;
            aIp.push_back( is );
        }
    }

    compareOriginDistance comp( aSeg.A );
    sort( aIp.begin(), aIp.end(), comp );

    return aIp.size();
}

static inline void addIntersection( SHAPE_LINE_CHAIN::INTERSECTIONS& aIps, int aPc, const SHAPE_LINE_CHAIN::INTERSECTION& aP )
{
    if( aIps.size() == 0 )
    {
        aIps.push_back( aP );
        return;
    }

    const auto& last = aIps.back();

    if( ( (last.our.Index() + 1) % aPc) == aP.our.Index() && last.p == aP.p )
        return;

    if( last.our.Index() == aP.our.Index() && last.p == aP.p )
        return;

    aIps.push_back( aP );
}

int SHAPE_LINE_CHAIN::Intersect( const SHAPE_LINE_CHAIN& aChain, INTERSECTIONS& aIp ) const
{
    BOX2I bb_other = aChain.BBox();

    for( int s1 = 0; s1 < SegmentCount(); s1++ )
    {
        const SEG& a = CSegment( s1 );
        const BOX2I bb_cur( a.A, a.B - a.A );

        if( !bb_other.Intersects( bb_cur ) )
            continue;

        for( int s2 = 0; s2 < aChain.SegmentCount(); s2++ )
        {
            const SEG& b = aChain.CSegment( s2 );
            INTERSECTION is;

            if( a.Collinear( b ) )
            {
                is.our = a;
                is.their = b;

                if( a.Contains( b.A ) ) { is.p = b.A; addIntersection(aIp, PointCount(), is); }
                if( a.Contains( b.B ) ) { is.p = b.B; addIntersection(aIp, PointCount(), is); }
                if( b.Contains( a.A ) ) { is.p = a.A; addIntersection(aIp, PointCount(), is); }
                if( b.Contains( a.B ) ) { is.p = a.B; addIntersection(aIp, PointCount(), is); }
            }
            else
            {
                OPT_VECTOR2I p = a.Intersect( b );

                if( p )
                {
                    is.p = *p;
                    is.our = a;
                    is.their = b;
                    addIntersection(aIp, PointCount(), is);
                }
            }
        }
    }

    return aIp.size();
}


int SHAPE_LINE_CHAIN::PathLength( const VECTOR2I& aP ) const
{
    int sum = 0;

    for( int i = 0; i < SegmentCount(); i++ )
    {
        const SEG seg = CSegment( i );
        int d = seg.Distance( aP );

        if( d <= 1 )
        {
            sum += ( aP - seg.A ).EuclideanNorm();
            return sum;
        }
        else
            sum += seg.Length();
    }

    return -1;
}


bool SHAPE_LINE_CHAIN_BASE::PointInside( const VECTOR2I& aPt, int aAccuracy,
                                         bool aUseBBoxCache ) const
{
    /*
     * Don't check the bounding box unless it's cached.  Building it is about the same speed as
     * the rigorous test below and so just slows things down by doing potentially two tests.
     */
    //if( aUseBBoxCache && !m_bbox.Contains( aPt ) )
        //return false;

    // fixme: bbox cache...

    if( !IsClosed() || GetPointCount() < 3 )
        return false;

    bool inside = false;

    int pointCount = GetPointCount();

    for( int i = 0; i < pointCount; )
    {
        const auto p1 = GetPoint( i++ );
        const auto p2 = GetPoint( i == pointCount ? 0 : i );
        const auto diff = p2 - p1;

        if( diff.y != 0 )
        {
            const int d = rescale( diff.x, ( aPt.y - p1.y ), diff.y );

            if( ( ( p1.y > aPt.y ) != ( p2.y > aPt.y ) ) && ( aPt.x - p1.x < d ) )
                inside = !inside;
        }
    }

    // If accuracy is <= 1 (nm) then we skip the accuracy test for performance.  Otherwise
    // we use "OnEdge(accuracy)" as a proxy for "Inside(accuracy)".
    if( aAccuracy <= 1 )
        return inside;
    else
        return inside || PointOnEdge( aPt, aAccuracy );
}


bool SHAPE_LINE_CHAIN_BASE::PointOnEdge( const VECTOR2I& aPt, int aAccuracy ) const
{
    return EdgeContainingPoint( aPt, aAccuracy ) >= 0;
}

int SHAPE_LINE_CHAIN_BASE::EdgeContainingPoint( const VECTOR2I& aPt, int aAccuracy ) const
{
    if( !GetPointCount() )
        return -1;

    else if( GetPointCount() == 1 )
    {
        VECTOR2I dist = GetPoint(0) - aPt;
        return ( hypot( dist.x, dist.y ) <= aAccuracy + 1 ) ? 0 : -1;
    }

    for( size_t i = 0; i < GetSegmentCount(); i++ )
    {
        const SEG s = GetSegment( i );

        if( s.A == aPt || s.B == aPt )
            return i;

        if( s.Distance( aPt ) <= aAccuracy + 1 )
            return i;
    }

    return -1;
}


bool SHAPE_LINE_CHAIN::CheckClearance( const VECTOR2I& aP, const int aDist) const
{
    if( !PointCount() )
        return false;

    else if( PointCount() == 1 )
        return m_points[0] == aP;

    for( int i = 0; i < SegmentCount(); i++ )
    {
        const SEG s = CSegment( i );

        if( s.A == aP || s.B == aP )
            return true;

        if( s.Distance( aP ) <= aDist )
            return true;
    }

    return false;
}


const OPT<SHAPE_LINE_CHAIN::INTERSECTION> SHAPE_LINE_CHAIN::SelfIntersecting() const
{
    for( int s1 = 0; s1 < SegmentCount(); s1++ )
    {
        for( int s2 = s1 + 1; s2 < SegmentCount(); s2++ )
        {
            const VECTOR2I s2a = CSegment( s2 ).A, s2b = CSegment( s2 ).B;

            if( s1 + 1 != s2 && CSegment( s1 ).Contains( s2a ) )
            {
                INTERSECTION is;
                is.our = CSegment( s1 );
                is.their = CSegment( s2 );
                is.p = s2a;
                return is;
            }
            else if( CSegment( s1 ).Contains( s2b ) &&
                     // for closed polylines, the ending point of the
                     // last segment == starting point of the first segment
                     // this is a normal case, not self intersecting case
                     !( IsClosed() && s1 == 0 && s2 == SegmentCount()-1 ) )
            {
                INTERSECTION is;
                is.our = CSegment( s1 );
                is.their = CSegment( s2 );
                is.p = s2b;
                return is;
            }
            else
            {
                OPT_VECTOR2I p = CSegment( s1 ).Intersect( CSegment( s2 ), true );

                if( p )
                {
                    INTERSECTION is;
                    is.our = CSegment( s1 );
                    is.their = CSegment( s2 );
                    is.p = *p;
                    return is;
                }
            }
        }
    }

    return OPT<SHAPE_LINE_CHAIN::INTERSECTION>();
}


SHAPE_LINE_CHAIN& SHAPE_LINE_CHAIN::Simplify( bool aRemoveColinear )
{
    std::vector<VECTOR2I> pts_unique;
    std::vector<ssize_t> shapes_unique;

    if( PointCount() < 2 )
    {
        return *this;
    }
    else if( PointCount() == 2 )
    {
        if( m_points[0] == m_points[1] )
            m_points.pop_back();

        return *this;
    }

    int i = 0;
    int np = PointCount();

    // stage 1: eliminate duplicate vertices
    while( i < np )
    {
        int j = i + 1;

        // We can eliminate duplicate vertices as long as they are part of the same shape, OR if
        // one of them is part of a shape and one is not.
        while( j < np && m_points[i] == m_points[j] &&
               ( m_shapes[i] == m_shapes[j] ||
                 m_shapes[i] == SHAPE_IS_PT ||
                 m_shapes[j] == SHAPE_IS_PT ) )
        {
            j++;
        }

        int shapeToKeep = m_shapes[i];

        if( shapeToKeep == SHAPE_IS_PT )
            shapeToKeep = m_shapes[j - 1];

        wxASSERT( shapeToKeep < static_cast<int>( m_arcs.size() ) );

        pts_unique.push_back( CPoint( i ) );
        shapes_unique.push_back( shapeToKeep );

        i = j;
    }

    m_points.clear();
    m_shapes.clear();
    np = pts_unique.size();

    i = 0;

    // stage 2: eliminate colinear segments
    while( i < np - 2 )
    {
        const VECTOR2I p0 = pts_unique[i];
        const VECTOR2I p1 = pts_unique[i + 1];
        int n = i;

        if( aRemoveColinear && shapes_unique[i] < 0 && shapes_unique[i + 1] < 0 )
        {
            while( n < np - 2
                    && ( SEG( p0, p1 ).LineDistance( pts_unique[n + 2] ) <= 1
                            || SEG( p0, p1 ).Collinear( SEG( p1, pts_unique[n + 2] ) ) ) )
                n++;
        }

        m_points.push_back( p0 );
        m_shapes.push_back( shapes_unique[i] );

        if( n > i )
            i = n;

        if( n == np - 2 )
        {
            m_points.push_back( pts_unique[np - 1] );
            m_shapes.push_back( shapes_unique[np - 1] );
            return *this;
        }

        i++;
    }

    if( np > 1 )
    {
        m_points.push_back( pts_unique[np - 2] );
        m_shapes.push_back( shapes_unique[np - 2] );
    }

    m_points.push_back( pts_unique[np - 1] );
    m_shapes.push_back( shapes_unique[np - 1] );

    assert( m_points.size() == m_shapes.size() );

    return *this;
}


const VECTOR2I SHAPE_LINE_CHAIN::NearestPoint( const VECTOR2I& aP,
                                               bool aAllowInternalShapePoints ) const
{
    int min_d = INT_MAX;
    int nearest = 0;

    for( int i = 0; i < SegmentCount(); i++ )
    {
        int d = CSegment( i ).Distance( aP );

        bool isInternalShapePoint = false;

        // An internal shape point here is everything after the start of an arc and before the
        // second-to-last vertex of the arc, because we are looking at segments here!
        if( i > 0 && i < SegmentCount() - 1 && m_shapes[i] >= 0 &&
                ( ( m_shapes[i - 1] >= 0 && m_shapes[i - 1] == m_shapes[i] ) &&
                  ( m_shapes[i + 2] >= 0 && m_shapes[i + 2] == m_shapes[i] ) ) )
        {
            isInternalShapePoint = true;
        }

        if( ( d < min_d ) && ( aAllowInternalShapePoints || !isInternalShapePoint ) )
        {
            min_d = d;
            nearest = i;
        }
    }

    // Is this the start of an arc?  If so, return it directly
    if( !aAllowInternalShapePoints &&
        ( ( nearest == 0 && m_shapes[nearest] >= 0 ) ||
          ( m_shapes[nearest] >= 0 && m_shapes[nearest] != m_shapes[nearest - 1] ) ) )
    {
        return m_points[nearest];
    }
    else if( !aAllowInternalShapePoints && nearest < SegmentCount() &&
             m_shapes[nearest] >= 0 && m_shapes[nearest + 1] == m_shapes[nearest] )
    {
        // If the nearest segment is the last of the arc, just return the arc endpoint
        return m_points[nearest + 1];
    }

    return CSegment( nearest ).NearestPoint( aP );
}


const VECTOR2I SHAPE_LINE_CHAIN::NearestPoint( const SEG& aSeg, int& dist ) const
{
    int nearest = 0;

    dist = INT_MAX;
    for( int i = 0; i < PointCount(); i++ )
    {
        int d = aSeg.LineDistance( CPoint( i ) );

        if( d < dist )
        {
            dist = d;
            nearest = i;
        }
    }

    return CPoint( nearest );
}


int SHAPE_LINE_CHAIN::NearestSegment( const VECTOR2I& aP ) const
{
    int min_d = INT_MAX;
    int nearest = 0;

    for( int i = 0; i < SegmentCount(); i++ )
    {
        int d = CSegment( i ).Distance( aP );

        if( d < min_d )
        {
            min_d = d;
            nearest = i;
        }
    }

    return nearest;
}


const std::string SHAPE_LINE_CHAIN::Format() const
{
    std::stringstream ss;


    ss << "SHAPE_LINE_CHAIN( { ";
    for( int i = 0; i < PointCount(); i++ )
    {
        ss << "VECTOR2I( " << m_points[i].x << ", " << m_points[i].y << ")";
        if( i != PointCount() -1 )
            ss << ", ";
    }

    ss << "}, " << ( m_closed ? "true" : "false" );
    ss << " );";



    return ss.str();


   /* fixme: arcs
    for( size_t i = 0; i < m_arcs.size(); i++ )
        ss << m_arcs[i].GetCenter().x << " " << m_arcs[i].GetCenter().y << " "
        << m_arcs[i].GetP0().x << " " << m_arcs[i].GetP0().y << " "
        << m_arcs[i].GetCentralAngle();

    return ss.str();*/
}


bool SHAPE_LINE_CHAIN::CompareGeometry ( const SHAPE_LINE_CHAIN & aOther ) const
{
    SHAPE_LINE_CHAIN a(*this), b( aOther );
    a.Simplify();
    b.Simplify();

    if( a.m_points.size() != b.m_points.size() )
        return false;

    for( int i = 0; i < a.PointCount(); i++)
        if( a.CPoint( i ) != b.CPoint( i ) )
            return false;
    return true;
}


bool SHAPE_LINE_CHAIN::Intersects( const SHAPE_LINE_CHAIN& aChain ) const
{
    INTERSECTIONS dummy;
    return Intersect( aChain, dummy ) != 0;
}


SHAPE* SHAPE_LINE_CHAIN::Clone() const
{
    return new SHAPE_LINE_CHAIN( *this );
}

bool SHAPE_LINE_CHAIN::Parse( std::stringstream& aStream )
{
    size_t n_pts;
    size_t n_arcs;

    m_points.clear();
    aStream >> n_pts;

    // Rough sanity check, just make sure the loop bounds aren't absolutely outlandish
    if( n_pts > aStream.str().size() )
        return false;

    aStream >> m_closed;
    aStream >> n_arcs;

    if( n_arcs > aStream.str().size() )
        return false;

    for( size_t i = 0; i < n_pts; i++ )
    {
        int x, y;
        ssize_t ind;
        aStream >> x;
        aStream >> y;
        m_points.emplace_back( x, y );

        aStream >> ind;
        m_shapes.push_back( ind );
    }

    for( size_t i = 0; i < n_arcs; i++ )
    {
        VECTOR2I p0, pc;
        double angle;

        aStream >> pc.x;
        aStream >> pc.y;
        aStream >> p0.x;
        aStream >> p0.y;
        aStream >> angle;

        m_arcs.emplace_back( pc, p0, angle );
    }

    return true;
}


const VECTOR2I SHAPE_LINE_CHAIN::PointAlong( int aPathLength ) const
{
    int total = 0;

    if( aPathLength == 0 )
        return CPoint( 0 );

    for( int i = 0; i < SegmentCount(); i++ )
    {
        const SEG& s = CSegment( i );
        int l = s.Length();

        if( total + l >= aPathLength )
        {
            VECTOR2I d( s.B - s.A );
            return s.A + d.Resize( aPathLength - total );
        }

        total += l;
    }

    return CPoint( -1 );
}

double SHAPE_LINE_CHAIN::Area() const
{
    // see https://www.mathopenref.com/coordpolygonarea2.html

    if( !m_closed )
        return 0.0;

    double area = 0.0;
    int size = m_points.size();

    for( int i = 0, j = size - 1; i < size; ++i )
    {
        area += ( (double) m_points[j].x + m_points[i].x ) * ( (double) m_points[j].y - m_points[i].y );
        j = i;
    }

    return -area * 0.5;
}


SHAPE_LINE_CHAIN::POINT_INSIDE_TRACKER::POINT_INSIDE_TRACKER( const VECTOR2I& aPoint ) :
    m_point( aPoint ),
    m_finished( false ),
    m_state( 0 ),
    m_count( 0 )
{
}


bool SHAPE_LINE_CHAIN::POINT_INSIDE_TRACKER::processVertex(
        const VECTOR2I& ip, const VECTOR2I& ipNext )
{
    if( ipNext.y == m_point.y )
    {
        if( ( ipNext.x == m_point.x )
                || ( ip.y == m_point.y && ( ( ipNext.x > m_point.x ) == ( ip.x < m_point.x ) ) ) )
        {
            m_finished = true;
            m_state    = -1;
            return false;
        }
    }

    if( ( ip.y < m_point.y ) != ( ipNext.y < m_point.y ) )
    {
        if( ip.x >= m_point.x )
        {
            if( ipNext.x > m_point.x )
            {
                m_state = 1 - m_state;
            }
            else
            {
                double d = (double) ( ip.x - m_point.x ) * ( ipNext.y - m_point.y )
                           - (double) ( ipNext.x - m_point.x ) * ( ip.y - m_point.y );

                if( !d )
                {
                    m_finished = true;
                    m_state    = -1;
                    return false;
                }

                if( ( d > 0 ) == ( ipNext.y > ip.y ) )
                    m_state = 1 - m_state;
            }
        }
        else
        {
            if( ipNext.x > m_point.x )
            {
                double d = (double) ( ip.x - m_point.x ) * ( ipNext.y - m_point.y )
                           - (double) ( ipNext.x - m_point.x ) * ( ip.y - m_point.y );

                if( !d )
                {
                    m_finished = true;
                    m_state    = -1;
                    return false;
                }

                if( ( d > 0 ) == ( ipNext.y > ip.y ) )
                    m_state = 1 - m_state;
            }
        }
    }
    return true;
}


void SHAPE_LINE_CHAIN::POINT_INSIDE_TRACKER::AddPolyline( const SHAPE_LINE_CHAIN& aPolyline )
{
    if( !m_count )
    {
        m_lastPoint = aPolyline.CPoint( 0 );
        m_firstPoint = aPolyline.CPoint( 0 );
    }

    m_count += aPolyline.PointCount();

    for( int i = 1; i < aPolyline.PointCount(); i++ )
    {
        auto p = aPolyline.CPoint( i );

        if( !processVertex( m_lastPoint, p ) )
            return;

        m_lastPoint = p;
    }

}


bool SHAPE_LINE_CHAIN::POINT_INSIDE_TRACKER::IsInside()
{
    processVertex( m_lastPoint, m_firstPoint );
    return m_state > 0;
}