bool PNS_LINE_PLACER::rhWalkOnly( const VECTOR2I& aP, PNS_LINE& aNewHead )
{
    PNS_LINE initTrack( m_head );
    PNS_LINE walkFull;
    int effort = 0;
    bool rv = true, viaOk;

    viaOk = buildInitialLine( aP, initTrack );

    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 )
    {
        walkFull.AppendVia( makeVia( walkFull.CPoint( -1 ) ) );
    }

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

    if( m_currentNode->CheckColliding( &walkFull ) )
    {
        aNewHead = m_head;
        return false;
    }

    m_head = walkFull;
    aNewHead = walkFull;

    return rv;
}
PNS_WALKAROUND::WalkaroundStatus PNS_WALKAROUND::singleStep( PNS_LINE& aPath,
        bool aWindingDirection )
{
    optional<PNS_OBSTACLE>& current_obs =
        aWindingDirection ? m_currentObstacle[0] : m_currentObstacle[1];
    bool& prev_recursive = aWindingDirection ? m_recursiveCollision[0] : m_recursiveCollision[1];

    if( !current_obs )
        return DONE;

    SHAPE_LINE_CHAIN path_pre[2], path_walk[2], path_post[2];

    VECTOR2I last = aPath.GetCLine().CPoint( -1 );

    if( ( current_obs->hull ).PointInside( last ) )
    {
        m_recursiveBlockageCount++;

        if( m_recursiveBlockageCount < 3 )
            aPath.GetLine().Append( current_obs->hull.NearestPoint( last ) );
        else
        {
            aPath = aPath.ClipToNearestObstacle( m_world );
            return STUCK;
        }
    }

    aPath.NewWalkaround( current_obs->hull, path_pre[0], path_walk[0],
            path_post[0], aWindingDirection );
    aPath.NewWalkaround( current_obs->hull, path_pre[1], path_walk[1],
            path_post[1], !aWindingDirection );

    int len_pre = path_walk[0].Length();
    int len_alt = path_walk[1].Length();

    PNS_LINE walk_path( aPath, path_walk[1] );

    bool alt_collides = m_world->CheckColliding( &walk_path,
            m_solids_only ? PNS_ITEM::SOLID : PNS_ITEM::ANY );

    SHAPE_LINE_CHAIN pnew;

    if( !m_forceSingleDirection && len_alt < len_pre && !alt_collides && !prev_recursive )
    {
        pnew = path_pre[1];
        pnew.Append( path_walk[1] );
        pnew.Append( path_post[1] );

        current_obs = nearestObstacle( PNS_LINE( aPath, path_post[1] ) );
        prev_recursive = false;
    }
    else
    {
        pnew = path_pre[0];
        pnew.Append( path_walk[0] );
        pnew.Append( path_post[0] );

        current_obs = nearestObstacle( PNS_LINE( aPath, path_walk[0] ) );

        if( !current_obs )
        {
            prev_recursive = false;
            current_obs = nearestObstacle( PNS_LINE( aPath, path_post[0] ) );
        }
        else
            prev_recursive = true;
    }

    pnew.Simplify();
    aPath.SetShape( pnew );

    return IN_PROGRESS;
}
PNS_WALKAROUND::WALKAROUND_STATUS PNS_WALKAROUND::singleStep( PNS_LINE& aPath,
                                                              bool aWindingDirection )
{
    optional<PNS_OBSTACLE>& current_obs =
        aWindingDirection ? m_currentObstacle[0] : m_currentObstacle[1];

    bool& prev_recursive = aWindingDirection ? m_recursiveCollision[0] : m_recursiveCollision[1];

    if( !current_obs )
        return DONE;

    SHAPE_LINE_CHAIN path_pre[2], path_walk[2], path_post[2];

    VECTOR2I last = aPath.CPoint( -1 );

    if( ( current_obs->m_hull ).PointInside( last ) || ( current_obs->m_hull ).PointOnEdge( last ) )
    {
        m_recursiveBlockageCount++;

        if( m_recursiveBlockageCount < 3 )
            aPath.Line().Append( current_obs->m_hull.NearestPoint( last ) );
        else
        {
            aPath = aPath.ClipToNearestObstacle( m_world );
            return DONE;
        }
    }

    aPath.Walkaround( current_obs->m_hull, path_pre[0], path_walk[0],
                      path_post[0], aWindingDirection );
    aPath.Walkaround( current_obs->m_hull, path_pre[1], path_walk[1],
                      path_post[1], !aWindingDirection );

#ifdef DEBUG
    m_logger.NewGroup( aWindingDirection ? "walk-cw" : "walk-ccw", m_iteration );
    m_logger.Log( &path_walk[0], 0, "path-walk" );
    m_logger.Log( &path_pre[0], 1, "path-pre" );
    m_logger.Log( &path_post[0], 4, "path-post" );
    m_logger.Log( &current_obs->m_hull, 2, "hull" );
    m_logger.Log( current_obs->m_item, 3, "item" );
#endif

    int len_pre = path_walk[0].Length();
    int len_alt = path_walk[1].Length();

    PNS_LINE walk_path( aPath, path_walk[1] );

    bool alt_collides = m_world->CheckColliding( &walk_path, m_itemMask );

    SHAPE_LINE_CHAIN pnew;

    if( !m_forceSingleDirection && len_alt < len_pre && !alt_collides && !prev_recursive )
    {
        pnew = path_pre[1];
        pnew.Append( path_walk[1] );
        pnew.Append( path_post[1] );

        if( !path_post[1].PointCount() || !path_walk[1].PointCount() )
            current_obs = nearestObstacle( PNS_LINE( aPath, path_pre[1] ) );
        else
            current_obs = nearestObstacle( PNS_LINE( aPath, path_post[1] ) );
        prev_recursive = false;
    }
    else
    {
        pnew = path_pre[0];
        pnew.Append( path_walk[0] );
        pnew.Append( path_post[0] );

        if( !path_post[0].PointCount() || !path_walk[0].PointCount() )
            current_obs = nearestObstacle( PNS_LINE( aPath, path_pre[0] ) );
        else
            current_obs = nearestObstacle( PNS_LINE( aPath, path_walk[0] ) );

        if( !current_obs )
        {
            prev_recursive = false;
            current_obs = nearestObstacle( PNS_LINE( aPath, path_post[0] ) );
        }
        else
            prev_recursive = true;
    }

    pnew.Simplify();
    aPath.SetShape( pnew );

    return IN_PROGRESS;
}