kicad/pcbnew/router/pns_line_placer.cpp

/*
 * KiRouter - a push-and-(sometimes-)shove PCB router
 *
 * Copyright (C) 2013-2014 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 3 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, see <http://www.gnu.org/licenses/>.
 */

#include <boost/foreach.hpp>
#include <boost/optional.hpp>

#include <colors.h>

#include "trace.h"

#include "pns_node.h"
#include "pns_line_placer.h"
#include "pns_walkaround.h"
#include "pns_shove.h"
#include "pns_utils.h"
#include "pns_router.h"

#include <class_board_item.h>

using boost::optional;

PNS_LINE_PLACER::PNS_LINE_PLACER( PNS_ROUTER* aRouter ) :
    PNS_ALGO_BASE ( aRouter )
{
    m_initial_direction = DIRECTION_45::N;
    m_iteration = 0;
    m_world = NULL;
    m_shove = NULL;
    m_currentNode = NULL;
}


PNS_LINE_PLACER::~PNS_LINE_PLACER()
{
    if( m_shove )
        delete m_shove;
}


void PNS_LINE_PLACER::setWorld ( PNS_NODE* aWorld )
{
    m_world = aWorld;
}


void PNS_LINE_PLACER::AddVia( bool aEnabled, int aDiameter, int aDrill )
{
    m_viaDiameter = aDiameter;
    m_viaDrill = aDrill;
    m_placingVia = aEnabled;
}


void PNS_LINE_PLACER::startPlacement( const VECTOR2I& aStart, int aNet, int aWidth, int aLayer )
{
    assert( m_world != NULL );
    
    m_direction = m_initial_direction;
    TRACE( 1, "world %p, intitial-direction %s layer %d\n",
            m_world % m_direction.Format().c_str() % aLayer );
    m_head.SetNet( aNet );
    m_tail.SetNet( aNet );
    m_head.SetWidth( aWidth );
    m_tail.SetWidth( aWidth );
    m_head.Line().Clear();
    m_tail.Line().Clear();
    m_head.SetLayer( aLayer );
    m_tail.SetLayer( aLayer );
    m_iteration = 0;
    m_p_start = aStart;

    m_lastNode = NULL;    
    m_currentNode = m_world;
    
    m_currentMode = Settings().Mode();

    if( m_shove )
        delete m_shove;
    
    m_shove = NULL;

    if( m_currentMode == RM_Shove || m_currentMode == RM_Smart )
    {
        m_shove = new PNS_SHOVE( m_world->Branch(), Router() );
    }
    
    m_placingVia = false;
}


void PNS_LINE_PLACER::setInitialDirection( const DIRECTION_45& aDirection )
{
    m_initial_direction = aDirection;

    if( m_tail.SegmentCount() == 0 )
            m_direction = aDirection;
}


bool PNS_LINE_PLACER::handleSelfIntersections()
{
    SHAPE_LINE_CHAIN::INTERSECTIONS ips;
    SHAPE_LINE_CHAIN& head = m_head.Line();
    SHAPE_LINE_CHAIN& tail = m_tail.Line();

    // if there is no tail, there is nothing to intersect with
    if( tail.PointCount() < 2 )
        return false;

    tail.Intersect( head, ips );

    // no intesection points - nothing to reduce
    if( ips.empty() )
        return false;

    int n = INT_MAX;
    VECTOR2I ipoint;

    // if there is more than one intersection, find the one that is
    // closest to the beginning of the tail.
    BOOST_FOREACH( SHAPE_LINE_CHAIN::INTERSECTION i, ips )
    {
        if( i.our.Index() < n )
        {
            n = i.our.Index();
            ipoint = i.p;
        }
    }

    // ignore the point where head and tail meet
    if( ipoint == head.CPoint( 0 ) || ipoint == tail.CPoint( -1 ) )
        return false;

    // Intersection point is on the first or the second segment: just start routing
    // from the beginning
    if( n < 2 )
    {
        m_p_start = tail.Point( 0 );
        m_direction = m_initial_direction;
        tail.Clear();
        head.Clear();

        return true;
    }
    else
    {
        // Clip till the last tail segment before intersection.
        // Set the direction to the one of this segment.
        const SEG last = tail.CSegment( n - 1 );
        m_p_start = last.A;
        m_direction = DIRECTION_45( last );
        tail.Remove( n, -1 );
        return true;
    }

    return false;
}


bool PNS_LINE_PLACER::handlePullback()
{
    SHAPE_LINE_CHAIN& head = m_head.Line();
    SHAPE_LINE_CHAIN& tail = m_tail.Line();

    if( head.PointCount() < 2 )
        return false;

    int n = tail.PointCount();

    if( n == 0 )
        return false;
    else if( n == 1 )
    {
        m_p_start = tail.CPoint( 0 );
        tail.Clear();
        return true;
    }

    DIRECTION_45 first_head( head.CSegment( 0 ) );
    DIRECTION_45 last_tail( tail.CSegment( -1 ) );
    DIRECTION_45::AngleType angle = first_head.Angle( last_tail );

    // case 1: we have a defined routing direction, and the currently computed
    // head goes in different one.
    bool pullback_1 = false;    // (m_direction != DIRECTION_45::UNDEFINED && m_direction != first_head);

    // case 2: regardless of the current routing direction, if the tail/head
    // extremities form an acute or right angle, reduce the tail by one segment
    // (and hope that further iterations) will result with a cleaner trace
    bool pullback_2 = ( angle == DIRECTION_45::ANG_RIGHT || angle == DIRECTION_45::ANG_ACUTE );

    if( pullback_1 || pullback_2 )
    {
        const SEG last = tail.CSegment( -1 );
        m_direction = DIRECTION_45( last );
        m_p_start = last.A;

        TRACE( 0, "Placer: pullback triggered [%d] [%s %s]",
                n % last_tail.Format().c_str() % first_head.Format().c_str() );

        // erase the last point in the tail, hoping that the next iteration will
        // result with a head trace that starts with a segment following our
        // current direction.
        if( n < 2 )
            tail.Clear(); // don't leave a single-point tail
        else
            tail.Remove( -1, -1 );

        if( !tail.SegmentCount() )
            m_direction = m_initial_direction;

        return true;
    }

    return false;
}


bool PNS_LINE_PLACER::reduceTail( const VECTOR2I& aEnd )
{
    SHAPE_LINE_CHAIN& head = m_head.Line();
    SHAPE_LINE_CHAIN& tail = m_tail.Line();

    int n = tail.SegmentCount();

    if( head.SegmentCount() < 1 )
        return false;

    // Don't attempt this for too short tails
    if( n < 2 )
        return false;

    // Start from the segment farthest from the end of the tail
    // int start_index = std::max(n - 1 - ReductionDepth, 0);

    DIRECTION_45 new_direction;
    VECTOR2I new_start;
    int reduce_index = -1;

    DIRECTION_45 head_dir( head.CSegment( 0 ) );

    for( int i = tail.SegmentCount() - 1; i >= 0; i-- )
    {
        const SEG s = tail.CSegment( i );
        DIRECTION_45 dir( s );

        // calculate a replacement route and check if it matches
        // the direction of the segment to be replaced
        SHAPE_LINE_CHAIN replacement = dir.BuildInitialTrace( s.A, aEnd );

        PNS_LINE tmp( m_tail, replacement );

        if( m_currentNode->CheckColliding( &tmp, PNS_ITEM::ANY ) )
            break;

        if( DIRECTION_45( replacement.CSegment( 0 ) ) == dir )
        {
            new_start = s.A;
            new_direction = dir;
            reduce_index = i;
        }
    }

    if( reduce_index >= 0 )
    {
        TRACE( 0, "Placer: reducing tail: %d", reduce_index );
        SHAPE_LINE_CHAIN reducedLine = new_direction.BuildInitialTrace( new_start, aEnd );

        m_p_start = new_start;
        m_direction = new_direction;
        tail.Remove( reduce_index + 1, -1 );
        head.Clear();
        return true;
    }

    if( !tail.SegmentCount() )
        m_direction = m_initial_direction;

    return false;
}


bool PNS_LINE_PLACER::checkObtusity( const SEG& aA, const SEG& aB ) const
{
    const DIRECTION_45 dir_a( aA );
    const DIRECTION_45 dir_b( aB );

    return dir_a.IsObtuse( dir_b ) || dir_a == dir_b;
}


bool PNS_LINE_PLACER::mergeHead()
{
    SHAPE_LINE_CHAIN& head = m_head.Line();
    SHAPE_LINE_CHAIN& tail = m_tail.Line();

    const int ForbiddenAngles = DIRECTION_45::ANG_ACUTE |
                                DIRECTION_45::ANG_HALF_FULL |
                                DIRECTION_45::ANG_UNDEFINED;

    head.Simplify();
    tail.Simplify();

    int n_head  = head.SegmentCount();
    int n_tail  = tail.SegmentCount();

    if( n_head < 3 )
    {
        TRACEn( 4, "Merge failed: not enough head segs." );
        return false;
    }

    if( n_tail && head.CPoint( 0 ) != tail.CPoint( -1 ) )
    {
        TRACEn( 4, "Merge failed: head and tail discontinuous." );
        return false;
    }

    if( m_head.CountCorners( ForbiddenAngles ) != 0 )
        return false;

    DIRECTION_45 dir_tail, dir_head;

    dir_head = DIRECTION_45( head.CSegment( 0 ) );

    if( n_tail )
    {
        dir_tail = DIRECTION_45( tail.CSegment( -1 ) );

        if( dir_head.Angle( dir_tail ) & ForbiddenAngles )
            return false;
    }

    if( !n_tail )
        tail.Append( head.CSegment( 0 ).A );

    for( int i = 0; i < n_head - 2; i++ )
    {
        tail.Append( head.CSegment( i ).B );
    }

    tail.Simplify();

    SEG last = tail.CSegment( -1 );

    m_p_start = last.B;
    m_direction = DIRECTION_45( last ).Right();

    head.Remove( 0, n_head - 2 );

    TRACE( 0, "Placer: merge %d, new direction: %s", n_head % m_direction.Format().c_str() );

    head.Simplify();
    tail.Simplify();

    return true;
}


bool PNS_LINE_PLACER::handleViaPlacement( PNS_LINE& aHead )
{
    if( !m_placingVia )
        return true;

    PNS_LAYERSET allLayers( 0, MAX_CU_LAYERS - 1 );
    PNS_VIA v( aHead.CPoint( -1 ), allLayers, m_viaDiameter, m_viaDrill, aHead.Net() );

    VECTOR2I force;
    VECTOR2I lead = aHead.CPoint( -1 ) - aHead.CPoint( 0 );

    bool solidsOnly = ( m_currentMode != RM_Walkaround );

    if( v.PushoutForce( m_currentNode, lead, force, solidsOnly, 40 ) )
    {
        SHAPE_LINE_CHAIN line = m_direction.BuildInitialTrace(
                aHead.CPoint( 0 ),
                aHead.CPoint( -1 ) + force );
        aHead = PNS_LINE( aHead, line );

        v.SetPos( v.Pos() + force );
        return true;
    }

    return false;
}


bool PNS_LINE_PLACER::rhWalkOnly( const VECTOR2I& aP, PNS_LINE& aNewHead )
{
    SHAPE_LINE_CHAIN line = m_direction.BuildInitialTrace( m_p_start, aP );
    PNS_LINE initTrack( m_head, line ), walkFull;
    int effort = 0;
    bool viaOk = handleViaPlacement( initTrack );
    bool rv = true;

    PNS_WALKAROUND walkaround( m_currentNode, Router() );

    walkaround.SetSolidsOnly( false );
    walkaround.SetIterationLimit( Settings().WalkaroundIterationLimit() );
    
    PNS_WALKAROUND::WALKAROUND_STATUS wf = walkaround.Route( initTrack, walkFull, false );

    switch( Settings().OptimizerEffort() )
    {
        case OE_LOW: 
            effort = 0;
            break;

        case OE_MEDIUM:
        case OE_FULL:
            effort = PNS_OPTIMIZER::MERGE_SEGMENTS;
            break;
    }

    if( Settings().SmartPads() )
        effort |= PNS_OPTIMIZER::SMART_PADS;

    if( wf == PNS_WALKAROUND::STUCK )
    {
        walkFull = walkFull.ClipToNearestObstacle( m_currentNode );
        rv = true;
    }
    else if( m_placingVia && viaOk )
    {
        PNS_LAYERSET allLayers( 0, MAX_CU_LAYERS - 1 );
        PNS_VIA v1( walkFull.CPoint( -1 ), allLayers, m_viaDiameter, m_viaDrill );
        walkFull.AppendVia( v1 );
    }

    PNS_OPTIMIZER::Optimize( &walkFull, effort, m_currentNode );

    if( m_currentNode->CheckColliding( &walkFull ) )
    {
        TRACEn(0, "strange, walk line colliding\n");
    }

    m_head = walkFull;
    aNewHead = walkFull;
    
    return rv;
}


bool PNS_LINE_PLACER::rhMarkObstacles( const VECTOR2I& aP, PNS_LINE& aNewHead )
{
    m_head.SetShape( m_direction.BuildInitialTrace( m_p_start, aP ) );
    
    if( m_placingVia )
    {
        PNS_LAYERSET allLayers( 0, MAX_CU_LAYERS - 1 );
        PNS_VIA v1( m_head.CPoint( -1 ), allLayers, m_viaDiameter, m_viaDrill );
        m_head.AppendVia( v1 );
    }

    aNewHead = m_head;
    
    return m_currentNode->CheckColliding( &m_head );
}


bool PNS_LINE_PLACER::rhShoveOnly ( const VECTOR2I& aP, PNS_LINE& aNewHead )
{
    SHAPE_LINE_CHAIN line = m_direction.BuildInitialTrace( m_p_start, aP );
    PNS_LINE initTrack( m_head, line );
    PNS_LINE walkSolids, l2;

    handleViaPlacement( initTrack );

    m_currentNode = m_shove->CurrentNode();
    PNS_OPTIMIZER optimizer( m_currentNode );

    PNS_WALKAROUND walkaround( m_currentNode, Router() );

    walkaround.SetSolidsOnly( true );
    walkaround.SetIterationLimit( 10 );
    PNS_WALKAROUND::WALKAROUND_STATUS stat_solids = walkaround.Route( initTrack, walkSolids );

    optimizer.SetEffortLevel( PNS_OPTIMIZER::MERGE_SEGMENTS );
    optimizer.SetCollisionMask ( PNS_ITEM::SOLID );
    optimizer.Optimize( &walkSolids );

    if( stat_solids == PNS_WALKAROUND::DONE )
        l2 = walkSolids;
    else
        l2 = initTrack.ClipToNearestObstacle( m_shove->CurrentNode() );

    PNS_LINE l( m_tail );
    l.Line().Append( l2.CLine() );
    l.Line().Simplify();

    if( m_placingVia )
    {
        PNS_LAYERSET allLayers( 0, MAX_CU_LAYERS - 1 );
        PNS_VIA v1( l.CPoint( -1 ), allLayers, m_viaDiameter, m_viaDrill );
        PNS_VIA v2( l2.CPoint( -1 ), allLayers, m_viaDiameter, m_viaDrill );

        l.AppendVia( v1 );
        l2.AppendVia( v2 );
    }

    l.Line().Simplify(); 

    // in certain, uncommon cases there may be loops in the head+tail, In such case, we don't shove to avoid
    // screwing up the database.
    if( l.HasLoops() )
    {
        aNewHead = m_head;
        return false;        
    }
    
    PNS_SHOVE::SHOVE_STATUS status = m_shove->ShoveLines( l );

    m_currentNode = m_shove->CurrentNode();

    if( status == PNS_SHOVE::SH_OK )
    {
        optimizer.SetWorld( m_currentNode );
        optimizer.SetEffortLevel( PNS_OPTIMIZER::MERGE_OBTUSE | PNS_OPTIMIZER::SMART_PADS );
        optimizer.SetCollisionMask( PNS_ITEM::ANY );
        optimizer.Optimize( &l2 );

        aNewHead = l2;

        return true;
    }
    else
    {
        walkaround.SetWorld( m_currentNode );
        walkaround.SetSolidsOnly( false );
        walkaround.SetIterationLimit( 10 );
        walkaround.SetApproachCursor( true, aP );
        walkaround.Route( initTrack, l2 );
        aNewHead = l2.ClipToNearestObstacle( m_shove->CurrentNode() );

        return false;
    }

    return false;
}


bool PNS_LINE_PLACER::routeHead( const VECTOR2I& aP, PNS_LINE& aNewHead )
{
    switch( m_currentMode )
    {
        case RM_MarkObstacles:
            return rhMarkObstacles( aP, aNewHead );
        case RM_Walkaround:
            return rhWalkOnly ( aP, aNewHead );
        case RM_Shove:
            return rhShoveOnly ( aP, aNewHead );
        default:
            break;
    }
 
    return false;
}


bool PNS_LINE_PLACER::optimizeTailHeadTransition()
{
    PNS_LINE tmp = Trace();

    if( PNS_OPTIMIZER::Optimize( &tmp, PNS_OPTIMIZER::FANOUT_CLEANUP, m_currentNode ) )
    {
        if( tmp.SegmentCount() < 1 )
            return false;

        m_head = tmp;        
        m_p_start = tmp.CLine().CPoint( 0 );
        m_direction = DIRECTION_45( tmp.CSegment( 0 ) );
        m_tail.Line().Clear();

        return true;
    }
    
    SHAPE_LINE_CHAIN& head = m_head.Line();
    SHAPE_LINE_CHAIN& tail = m_tail.Line();

    int tailLookbackSegments = 3;

    //if(m_currentMode() == RM_Walkaround)
    //    tailLookbackSegments = 10000;

    int threshold = std::min( tail.PointCount(), tailLookbackSegments + 1 );

    if( tail.SegmentCount() < 3 )
        return false;

    // assemble TailLookbackSegments tail segments with the current head
    SHAPE_LINE_CHAIN opt_line = tail.Slice( -threshold, -1 );

    int end = std::min(2, head.PointCount() - 1 );

    opt_line.Append( head.Slice( 0, end ) );

    PNS_LINE new_head( m_tail, opt_line );

    // and see if it could be made simpler by merging obtuse/collnear segments.
    // If so, replace the (threshold) last tail points and the head with
    // the optimized line

    if( PNS_OPTIMIZER::Optimize( &new_head, PNS_OPTIMIZER::MERGE_OBTUSE, m_currentNode ) )
    {
        PNS_LINE tmp( m_tail, opt_line );

        TRACE( 0, "Placer: optimize tail-head [%d]", threshold );

        head.Clear();
        tail.Replace( -threshold, -1, new_head.CLine() );
        tail.Simplify();

        m_p_start = new_head.CLine().CPoint( -1 );
        m_direction = DIRECTION_45( new_head.CSegment( -1 ) );

        return true;
    }

    return false;
}


void PNS_LINE_PLACER::routeStep( const VECTOR2I& aP )
{
    bool fail = false;
    bool go_back = false;

    int i, n_iter = 1;

    PNS_LINE new_head;

    TRACE( 2, "INIT-DIR: %s head: %d, tail: %d segs\n",
            m_initial_direction.Format().c_str() % m_head.SegmentCount() %
            m_tail.SegmentCount() );

    for( i = 0; i < n_iter; i++ )
    {
        if( !go_back && Settings().FollowMouse() )
            reduceTail( aP );

        go_back = false;

        if( !routeHead( aP, new_head ) )
            fail = true;

        if( !new_head.Is45Degree() )
            fail = true;

        if( !Settings().FollowMouse() )
            return;

        m_head = new_head;

        if( handleSelfIntersections() )
        {
            n_iter++;
            go_back = true;
        }

        if( !go_back && handlePullback() )
        {
            n_iter++;
            go_back = true;
        }
    }

    if( !fail )
    {
       if( optimizeTailHeadTransition() )
          return;

        mergeHead();
    }
}


bool PNS_LINE_PLACER::route( const VECTOR2I& aP )
{
    routeStep( aP );
    return CurrentEnd() == aP;
}


const PNS_LINE PNS_LINE_PLACER::Trace() const
{
    PNS_LINE tmp( m_head );

    tmp.SetShape( m_tail.CLine() );
    tmp.Line().Append( m_head.CLine() );
    tmp.Line().Simplify();
    return tmp;
}


const PNS_ITEMSET PNS_LINE_PLACER::Traces() 
{
    m_currentTrace = Trace(); 
    return PNS_ITEMSET( &m_currentTrace );
}


void PNS_LINE_PLACER::FlipPosture()
{
    m_initial_direction = m_initial_direction.Right();
    m_direction = m_direction.Right();
}


PNS_NODE* PNS_LINE_PLACER::CurrentNode( bool aLoopsRemoved ) const
{
    if( aLoopsRemoved && m_lastNode )
        return m_lastNode;

    return m_currentNode;
}


void PNS_LINE_PLACER::splitAdjacentSegments( PNS_NODE* aNode, PNS_ITEM* aSeg, const VECTOR2I& aP )
{
    if( aSeg && aSeg->OfKind( PNS_ITEM::SEGMENT ) )
    {
        PNS_JOINT *jt = aNode->FindJoint( aP, aSeg );

        if( jt && jt->LinkCount() >= 1 )
            return;

        PNS_SEGMENT* s_old = static_cast<PNS_SEGMENT*>( aSeg );
        
        PNS_SEGMENT* s_new[2];

        s_new[0] = s_old->Clone();
        s_new[1] = s_old->Clone();

        s_new[0]->SetEnds( s_old->Seg().A, aP );
        s_new[1]->SetEnds( aP, s_old->Seg().B );

        aNode->Remove( s_old );
        aNode->Add( s_new[0], true );
        aNode->Add( s_new[1], true );
    }
}


void PNS_LINE_PLACER::SetLayer(int aLayer)
{
    m_currentLayer = aLayer;
}


void PNS_LINE_PLACER::Start( const VECTOR2I& aP, PNS_ITEM* aStartItem )
{
    VECTOR2I p( aP );

    static int unknowNetIdx = 0;    // -10000;
    int net = -1;

    m_lastNode = NULL;
    m_placingVia = false;
    m_startsOnVia = false;
    
    bool splitSeg = false;

    if( Router()->SnappingEnabled() )
        p = Router()->SnapToItem( aStartItem, aP, splitSeg );
    
    if( !aStartItem || aStartItem->Net() < 0 )
        net = unknowNetIdx--;
    else
        net = aStartItem->Net();

    m_currentStart  = p;
    m_originalStart = p;
    m_currentEnd = p;
    m_currentNet = net;

    PNS_NODE *rootNode = Router()->GetWorld()->Branch();

    if( splitSeg )
        splitAdjacentSegments( rootNode, aStartItem, p );
    
    setWorld ( rootNode );
    setInitialDirection( Settings().InitialDirection() );
    startPlacement( p, m_currentNet, m_currentWidth, m_currentLayer );
}


void PNS_LINE_PLACER::Move( const VECTOR2I& aP, PNS_ITEM* aEndItem )
{
    PNS_LINE current;
    VECTOR2I p = aP;
    int eiDepth = -1;
    
    if( aEndItem && aEndItem->Owner() )
        eiDepth = aEndItem->Owner()->Depth();
    
    if( m_lastNode )
    {
        delete m_lastNode;
        m_lastNode = NULL;
    }
    
    route( p );

    current = Trace();
    
    if( !current.PointCount() )
        m_currentEnd = m_p_start;
    else
        m_currentEnd = current.CLine().CPoint( -1 );

    PNS_NODE* latestNode = m_currentNode;
    m_lastNode = latestNode->Branch();
    
    if( eiDepth >= 0 && aEndItem && latestNode->Depth() > eiDepth &&
            current.SegmentCount() && current.CPoint( -1 ) == aP )
    {
        splitAdjacentSegments( m_lastNode, aEndItem, current.CPoint( -1 ) );

        if( Settings().RemoveLoops() )
            removeLoops( m_lastNode, &current );       
    }

    updateLeadingRatLine();
}


bool PNS_LINE_PLACER::FixRoute( const VECTOR2I& aP, PNS_ITEM* aEndItem )
{
    bool realEnd = false;
    int lastV;
    
    PNS_LINE pl = Trace();

    if (m_currentMode == RM_MarkObstacles && 
        !Settings().CanViolateDRC() &&
        m_world->CheckColliding( &pl ) )
            return false;

    const SHAPE_LINE_CHAIN& l = pl.CLine();

    if( !l.SegmentCount() )
        return true;

    VECTOR2I p_pre_last = l.CPoint( -1 );
    const VECTOR2I p_last = l.CPoint( -1 );
    DIRECTION_45 d_last( l.CSegment( -1 ) );

    if( l.PointCount() > 2 )
        p_pre_last = l.CPoint( -2 );

    if( aEndItem && m_currentNet >= 0 && m_currentNet == aEndItem->Net() )
        realEnd = true;

    if( realEnd || m_placingVia )
        lastV = l.SegmentCount();
    else
        lastV = std::max( 1, l.SegmentCount() - 1 );

    PNS_SEGMENT* lastSeg = NULL;

    for( int i = 0; i < lastV; i++ )
    {
        const SEG& s = pl.CSegment( i );
        PNS_SEGMENT* seg = new PNS_SEGMENT( s, m_currentNet );
        seg->SetWidth( pl.Width() );
        seg->SetLayer( m_currentLayer );
        m_lastNode->Add( seg );
        lastSeg = seg;
    }

    if( pl.EndsWithVia() )
        m_lastNode->Add( pl.Via().Clone() );

    if( realEnd )
        simplifyNewLine ( m_lastNode, lastSeg );
 
    Router()->CommitRouting ( m_lastNode );
    
    m_lastNode = NULL;

    if( !realEnd )
    {
        setInitialDirection( d_last );
        VECTOR2I p_start = m_placingVia ? p_last : p_pre_last;

        if( m_placingVia )
            m_currentLayer = Router()->NextCopperLayer( true );

        setWorld ( Router()->GetWorld()->Branch() );
        startPlacement( p_start, m_head.Net(), m_head.Width(), m_currentLayer );

        m_startsOnVia = m_placingVia;
        m_placingVia = false;
    }

    return realEnd;
}


void PNS_LINE_PLACER::removeLoops( PNS_NODE* aNode, PNS_LINE* aLatest )
{
    if( !aLatest->SegmentCount() )
        return;

    aNode->Add( aLatest, true );
    
    for( int s = 0; s < aLatest->SegmentCount(); s++ )
    {
        PNS_SEGMENT *seg = ( *aLatest->LinkedSegments() )[s];
        PNS_LINE* ourLine = aNode->AssembleLine( seg );
        PNS_JOINT a, b;
        std::vector<PNS_LINE*> lines;

        aNode->FindLineEnds( ourLine, a, b );

        if( a == b )
        {
            aNode->FindLineEnds( aLatest, a, b);
        }
        
        aNode->FindLinesBetweenJoints( a, b, lines );

        int removedCount = 0;
        int total = 0;

        BOOST_FOREACH( PNS_LINE* line, lines )
        {
            total++;

            if( !( line->ContainsSegment( seg ) ) && line->SegmentCount() )
            {
                Router()->DisplayDebugLine ( line->CLine(), -1, 10000 );

                for( int i = 0; i < line->PointCount(); i++ )
                    Router()->DisplayDebugPoint( line->CPoint( i ), -1 );

                aNode->Remove( line );
                removedCount ++;
            }
        }

        TRACE( 0, "total segs removed: %d/%d\n", removedCount % total );

        delete ourLine;
    }
    
    aNode->Remove( aLatest );
}


void PNS_LINE_PLACER::simplifyNewLine( PNS_NODE* aNode, PNS_SEGMENT* aLatest )
{
    PNS_LINE* l = aNode->AssembleLine( aLatest );
    SHAPE_LINE_CHAIN simplified ( l->CLine() );

    simplified.Simplify();

    if( simplified.PointCount() != l->PointCount() )
    {
        std::auto_ptr<PNS_LINE> lnew ( l->Clone() );
        aNode -> Remove(l);
        lnew->SetShape(simplified);
        aNode -> Add( lnew.get() );
    }
}


void PNS_LINE_PLACER::UpdateSizes( const PNS_ROUTING_SETTINGS& aSettings )
{
    int trackWidth = aSettings.GetTrackWidth();

    m_head.SetWidth( trackWidth );
    m_tail.SetWidth( trackWidth );

    m_currentWidth = trackWidth;
    m_viaDiameter = aSettings.GetViaDiameter();
    m_viaDrill = aSettings.GetViaDrill();
}


void PNS_LINE_PLACER::updateLeadingRatLine()
{
    PNS_LINE current = Trace();
    
    if( !current.PointCount() )
        return;

    std::auto_ptr<PNS_NODE> tmpNode ( m_lastNode->Branch() );
    tmpNode->Add( &current );

    PNS_JOINT *jt = tmpNode->FindJoint( current.CPoint( -1 ),
                                        current.Layers().Start(), current.Net() );

    if( !jt )
        return;
    
    int anchor;
    PNS_ITEM *it = tmpNode->NearestUnconnectedItem( jt, &anchor );

    if( it )
    {
        SHAPE_LINE_CHAIN lc;
        lc.Append ( current.CPoint( -1 ) );
        lc.Append ( it->Anchor( anchor ) );
        Router()->DisplayDebugLine( lc, 5, 10000 );
    }
}