pns_line_placer.cpp

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/*
 * KiRouter - a push-and-(sometimes-)shove PCB router
 *
 * Copyright (C) 2013-2017 CERN
 * Copyright (C) 2016-2024 KiCad Developers, see AUTHORS.txt for contributors.
 * Author: Tomasz Wlostowski <[email protected]>
 *
 * 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 <optional>
#include <memory>
 
#include "pns_arc.h"
#include "pns_debug_decorator.h"
#include "pns_line_placer.h"
#include "pns_node.h"
#include "pns_router.h"
#include "pns_shove.h"
#include "pns_solid.h"
#include "pns_topology.h"
#include "pns_walkaround.h"
#include "pns_mouse_trail_tracer.h"
 
#include <wx/log.h>
 
namespace PNS {
 
LINE_PLACER::LINE_PLACER( ROUTER* aRouter ) :
 PLACEMENT_ALGO( aRouter )
{
 m_initial_direction = DIRECTION_45::N;
 m_world = nullptr;
 m_shove = nullptr;
 m_currentNode = nullptr;
 m_idle = true;
 
 // Init temporary variables (do not leave uninitialized members)
 m_lastNode = nullptr;
 m_placingVia = false;
 m_currentNet = nullptr;
 m_currentLayer = 0;
 m_startItem = nullptr;
 m_endItem = nullptr;
 m_chainedPlacement = false;
 m_orthoMode = false;
 m_placementCorrect = false;
}
 
 
LINE_PLACER::~LINE_PLACER()
{
}
 
 
void LINE_PLACER::setWorld( NODE* aWorld )
{
 m_world = aWorld;
}
 
 
const VIA LINE_PLACER::makeVia( const VECTOR2I& aP )
{
 const LAYER_RANGE layers( m_sizes.ViaType() == VIATYPE::THROUGH ? F_Cu : m_sizes.GetLayerTop(),
 m_sizes.ViaType() == VIATYPE::THROUGH ? B_Cu : m_sizes.GetLayerBottom() );
 
 return VIA( aP, layers, m_sizes.ViaDiameter(), m_sizes.ViaDrill(), nullptr, m_sizes.ViaType() );
}
 
 
bool LINE_PLACER::ToggleVia( bool aEnabled )
{
 m_placingVia = aEnabled;
 
 if( !aEnabled )
 m_head.RemoveVia();
 
 return true;
}
 
 
void LINE_PLACER::setInitialDirection( const DIRECTION_45& aDirection )
{
 m_initial_direction = aDirection;
 
 if( m_tail.SegmentCount() == 0 )
 m_direction = aDirection;
}
 
 
bool 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;
 
 if( head.PointCount() < 2 )
 return false;
 
 // completely new head trace? chop off the tail
 if( tail.CPoint(0) == head.CPoint(0) )
 {
 m_direction = m_initial_direction;
 tail.Clear();
 return true;
 }
 
 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.
 for( const SHAPE_LINE_CHAIN::INTERSECTION& i : ips )
 {
 if( i.index_our < n )
 {
 n = i.index_our;
 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_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_direction = DIRECTION_45( last );
 tail.Remove( n, -1 );
 return true;
 }
 
 return false;
}
 
 
bool 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 )
 {
 tail.Clear();
 return true;
 }
 
 DIRECTION_45 first_head, last_tail;
 
 wxASSERT( tail.PointCount() >= 2 );
 
 if( !head.IsPtOnArc( 0 ) )
 first_head = DIRECTION_45( head.CSegment( 0 ) );
 else
 first_head = DIRECTION_45( head.CArcs()[head.ArcIndex(0)] );
 
 int lastSegIdx = tail.PointCount() - 2;
 
 if( !tail.IsPtOnArc( lastSegIdx ) )
 last_tail = DIRECTION_45( tail.CSegment( lastSegIdx ) );
 else
 last_tail = DIRECTION_45( tail.CArcs()[tail.ArcIndex(lastSegIdx)] );
 
 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 )
 {
 if( !tail.IsArcSegment( lastSegIdx ) )
 {
 const SEG& seg = tail.CSegment( lastSegIdx );
 m_direction = DIRECTION_45( seg );
 PNS_DBG( Dbg(), AddPoint, m_p_start, WHITE, 10000, wxT( "new-pstart [pullback3]" ) );
 
 }
 else
 {
 const SHAPE_ARC& arc = tail.CArcs()[tail.ArcIndex( lastSegIdx )];
 m_direction = DIRECTION_45( arc );
 }
 
 PNS_DBG( Dbg(), Message, wxString::Format( "Placer: pullback triggered [%d] [%s %s]",
 n, last_tail.Format(), first_head.Format() ) );
 
 // 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.RemoveShape( -1 );
 
 if( !tail.SegmentCount() )
 m_direction = m_initial_direction;
 
 return true;
 }
 
 return false;
}
 
 
bool 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;
 
 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 );
 
 if( replacement.SegmentCount() < 1 )
 continue;
 
 LINE tmp( m_tail, replacement );
 
 if( m_currentNode->CheckColliding( &tmp, ITEM::ANY_T ) )
 break;
 
 if( DIRECTION_45( replacement.CSegment( 0 ) ) == dir )
 {
 new_start = s.A;
 new_direction = dir;
 reduce_index = i;
 }
 }
 
 if( reduce_index >= 0 )
 {
 PNS_DBG( Dbg(), Message, wxString::Format( "Placer: reducing tail: %d" , reduce_index ) );
 SHAPE_LINE_CHAIN reducedLine = new_direction.BuildInitialTrace( new_start, aEnd );
 
 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 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.ShapeCount();
 int n_tail = tail.ShapeCount();
 
 if( n_head < 3 )
 {
 PNS_DBG( Dbg(), Message, wxT( "Merge failed: not enough head segs." ) );
 return false;
 }
 
 if( n_tail && head.CPoint( 0 ) != tail.CPoint( -1 ) )
 {
 PNS_DBG( Dbg(), Message, wxT( "Merge failed: head and tail discontinuous." ) );
 return false;
 }
 
 if( m_head.CountCorners( ForbiddenAngles ) != 0 )
 return false;
 
 DIRECTION_45 dir_tail, dir_head;
 
 if( !head.IsPtOnArc( 0 ) )
 dir_head = DIRECTION_45( head.CSegment( 0 ) );
 else
 dir_head = DIRECTION_45( head.CArcs()[head.ArcIndex( 0 )] );
 
 if( n_tail )
 {
 wxASSERT( tail.PointCount() >= 2 );
 int lastSegIdx = tail.PointCount() - 2;
 
 if( !tail.IsPtOnArc( lastSegIdx ) )
 dir_tail = DIRECTION_45( tail.CSegment( -1 ) );
 else
 dir_tail = DIRECTION_45( tail.CArcs()[tail.ArcIndex( lastSegIdx )] );
 
 if( dir_head.Angle( dir_tail ) & ForbiddenAngles )
 return false;
 }
 
 tail.Append( head );
 
 tail.Simplify();
 
 int lastSegIdx = tail.PointCount() - 2;
 
 if( !tail.IsArcSegment( lastSegIdx ) )
 m_direction = DIRECTION_45( tail.CSegment( -1 ) );
 else
 m_direction = DIRECTION_45( tail.CArcs()[tail.ArcIndex( lastSegIdx )] );
 
 head.Remove( 0, -1 );
 
 PNS_DBG( Dbg(), Message, wxString::Format( "Placer: merge %d, new direction: %s" , n_head,
 m_direction.Format() ) );
 
 head.Simplify();
 tail.Simplify();
 
 return true;
}
 
 
bool LINE_PLACER::clipAndCheckCollisions( const VECTOR2I& aP, const SHAPE_LINE_CHAIN& aL,
 SHAPE_LINE_CHAIN& aOut, int &thresholdDist )
{
 SHAPE_LINE_CHAIN l( aL );
 int idx = l.Split( aP );
 
 if( idx < 0)
 return false;
 
 bool rv = true;
 
 SHAPE_LINE_CHAIN l2 = l.Slice( 0, idx );
 int dist = l2.Length();
 
 PNS_DBG( Dbg(), AddPoint, aP, BLUE, 500000, wxString::Format( "hug-target-check-%d", idx ) );
 PNS_DBG( Dbg(), AddShape, &l2, BLUE, 500000, wxT( "hug-target-line" ) );
 
 if( dist < thresholdDist )
 rv = false;
 
 LINE ctest( m_head, l2 );
 
 if( m_currentNode->CheckColliding( &ctest ).has_value() )
 rv = false;
 
 if( rv )
 {
 aOut = l2;
 thresholdDist = dist;
 }
 
 return rv;
}
 
 
bool LINE_PLACER::cursorDistMinimum( const SHAPE_LINE_CHAIN& aL, const VECTOR2I& aCursor,
 double lengthThreshold, SHAPE_LINE_CHAIN &aOut )
{
 std::vector<int> dists;
 std::vector<VECTOR2I> pts;
 
 if( aL.PointCount() == 0 )
 return false;
 
 VECTOR2I lastP = aL.CPoint(-1);
 int accumulatedDist = 0;
 
 dists.reserve( 2 * aL.PointCount() );
 
 for( int i = 0; i < aL.SegmentCount(); i++ )
 {
 const SEG& s = aL.CSegment( i );
 
 dists.push_back( ( aCursor - s.A ).EuclideanNorm() );
 pts.push_back( s.A );
 auto pn = s.NearestPoint( aCursor );
 
 if( pn != s.A && pn != s.B )
 {
 dists.push_back( ( pn - aCursor ).EuclideanNorm() );
 pts.push_back( pn );
 }
 
 accumulatedDist += s.Length();
 
 if ( accumulatedDist > lengthThreshold )
 {
 lastP = s.B;
 break;
 }
 }
 
 dists.push_back( ( aCursor - lastP ).EuclideanNorm() );
 pts.push_back( lastP );
 
 int minDistLoc = std::numeric_limits<int>::max();
 int minPLoc = -1;
 int minDistGlob = std::numeric_limits<int>::max();
 int minPGlob = -1;
 
 for( int i = 0; i < dists.size(); i++ )
 {
 int d = dists[i];
 
 if( d < minDistGlob )
 {
 minDistGlob = d;
 minPGlob = i;
 }
 }
 
 if( dists.size() >= 3 )
 {
 for( int i = 0; i < dists.size() - 3; i++ )
 {
 if( dists[i + 2] > dists[i + 1] && dists[i] > dists[i + 1] )
 {
 int d = dists[i + 1];
 if( d < minDistLoc )
 {
 minDistLoc = d;
 minPLoc = i + 1;
 }
 }
 }
 
 if( dists.back() < minDistLoc && minPLoc >= 0 )
 {
 minDistLoc = dists.back();
 minPLoc = dists.size() - 1;
 }
 }
 else
 {
 // Too few points: just use the global
 minDistLoc = minDistGlob;
 minPLoc = minPGlob;
 }
 
// fixme: I didn't make my mind yet if local or global minimum feels better. I'm leaving both
// in the code, enabling the global one by default
 minPLoc = -1;
 int preferred;
 
 if( minPLoc < 0 )
 {
 preferred = minPGlob;
 }
 else
 {
 preferred = minPLoc;
 }
 
 int thresholdDist = 0;
 
 if( clipAndCheckCollisions( pts[preferred], aL, aOut, thresholdDist ) )
 return true;
 
 thresholdDist = 0;
 
 SHAPE_LINE_CHAIN l( aL ), prefL;
 int minDist = std::numeric_limits<int>::max();
 
 bool ok = false;
 
 for( int i = 0; i < pts.size() ; i++)
 {
 //PNS_DBG( Dbg(), AddPoint, pts[i], BLUE, 500000, wxT( "hug-target-fallback" ) );
 
 ok |= clipAndCheckCollisions( pts[i], aL, aOut, thresholdDist );
 }
 
 return ok;
}
 
 
bool LINE_PLACER::rhWalkBase( const VECTOR2I& aP, LINE& aWalkLine, int aCollisionMask,
 bool& aViaOk )
{
 LINE walkFull( m_head );
 LINE l1( m_head );
 
 PNS_DBG( Dbg(), AddItem, &m_tail, GREEN, 100000, wxT( "walk-base-old-tail" ) );
 PNS_DBG( Dbg(), AddItem, &m_head, BLUE, 100000, wxT( "walk-base-old-head" ) );
 
 VECTOR2I walkP = aP;
 
 WALKAROUND walkaround( m_currentNode, Router() );
 
 walkaround.SetSolidsOnly( false );
 walkaround.SetDebugDecorator( Dbg() );
 walkaround.SetLogger( Logger() );
 walkaround.SetIterationLimit( Settings().WalkaroundIterationLimit() );
 walkaround.SetItemMask( aCollisionMask );
 
 int round = 0;
 
 do
 {
 l1.Clear();
 
 PNS_DBG( Dbg(), BeginGroup, wxString::Format( "walk-round-%d", round ), 0 );
 round++;
 
 aViaOk = buildInitialLine( walkP, l1, round == 0 );
 PNS_DBG( Dbg(), AddItem, &l1, BLUE, 20000, wxT( "walk-base-l1" ) );
 
 if( l1.EndsWithVia() )
 PNS_DBG( Dbg(), AddPoint, l1.Via().Pos(), BLUE, 100000, wxT( "walk-base-l1-via" ) );
 
 LINE initTrack( m_tail );
 initTrack.Line().Append( l1.CLine() );
 initTrack.Line().Simplify();
 
 
 double initialLength = initTrack.CLine().Length();
 double hugThresholdLength = initialLength * Settings().WalkaroundHugLengthThreshold();
 double hugThresholdLengthComplete =
 2.0 * initialLength * Settings().WalkaroundHugLengthThreshold();
 
 WALKAROUND::RESULT wr = walkaround.Route( initTrack );
 std::optional<LINE> bestLine;
 
 OPTIMIZER optimizer( m_currentNode );
 
 optimizer.SetEffortLevel( OPTIMIZER::MERGE_SEGMENTS );
 optimizer.SetCollisionMask( aCollisionMask );
 
 int len_cw = wr.statusCw != WALKAROUND::STUCK ? wr.lineCw.CLine().Length()
 : std::numeric_limits<int>::max();
 int len_ccw = wr.statusCcw != WALKAROUND::STUCK ? wr.lineCcw.CLine().Length()
 : std::numeric_limits<int>::max();
 
 if( wr.statusCw == WALKAROUND::DONE )
 {
 PNS_DBG( Dbg(), AddItem, &wr.lineCw, BLUE, 20000, wxT( "wf-result-cw-preopt" ) );
 LINE tmpHead, tmpTail;
 
 if( splitHeadTail( wr.lineCw, m_tail, tmpHead, tmpTail ) )
 {
 optimizer.Optimize( &tmpHead );
 wr.lineCw.SetShape( tmpTail.CLine () );
 wr.lineCw.Line().Append( tmpHead.CLine( ) );
 }
 
 PNS_DBG( Dbg(), AddItem, &wr.lineCw, RED, 20000, wxT( "wf-result-cw-postopt" ) );
 len_cw = wr.lineCw.CLine().Length();
 bestLine = wr.lineCw;
 }
 
 if( wr.statusCcw == WALKAROUND::DONE )
 {
 PNS_DBG( Dbg(), AddItem, &wr.lineCcw, BLUE, 20000, wxT( "wf-result-ccw-preopt" ) );
 
 LINE tmpHead, tmpTail;
 
 if( splitHeadTail( wr.lineCw, m_tail, tmpHead, tmpTail ) )
 {
 optimizer.Optimize( &tmpHead );
 wr.lineCw.SetShape( tmpTail.CLine () );
 wr.lineCw.Line().Append( tmpHead.CLine( ) );
 }
 
 PNS_DBG( Dbg(), AddItem, &wr.lineCcw, RED, 20000, wxT( "wf-result-ccw-postopt" ) );
 len_ccw = wr.lineCcw.CLine().Length();
 
 if( len_ccw < len_cw )
 bestLine = wr.lineCcw;
 }
 
 int bestLength = len_cw < len_ccw ? len_cw : len_ccw;
 
 if( bestLength < hugThresholdLengthComplete && bestLine.has_value() )
 {
 walkFull.SetShape( bestLine->CLine() );
 walkP = walkFull.CLine().CPoint(-1);
 PNS_DBGN( Dbg(), EndGroup );
 continue;
 }
 
 bool validCw = false;
 bool validCcw = false;
 int distCcw = std::numeric_limits<int>::max();
 int distCw = std::numeric_limits<int>::max();
 
 SHAPE_LINE_CHAIN l_cw, l_ccw;
 
 if( wr.statusCw != WALKAROUND::STUCK )
 {
 validCw = cursorDistMinimum( wr.lineCw.CLine(), aP, hugThresholdLength, l_cw );
 
 if( validCw )
 distCw = ( aP - l_cw.CPoint( -1 ) ).EuclideanNorm();
 
 PNS_DBG( Dbg(), AddShape, &l_cw, MAGENTA, 200000, wxString::Format( "wh-result-cw %s",
 validCw ? "non-colliding"
 : "colliding" ) );
 }
 
 if( wr.statusCcw != WALKAROUND::STUCK )
 {
 validCcw = cursorDistMinimum( wr.lineCcw.CLine(), aP, hugThresholdLength, l_ccw );
 
 if( validCcw )
 distCcw = ( aP - l_ccw.CPoint( -1 ) ).EuclideanNorm();
 
 PNS_DBG( Dbg(), AddShape, &l_ccw, MAGENTA, 200000, wxString::Format( "wh-result-ccw %s",
 validCcw ? "non-colliding"
 : "colliding" ) );
 }
 
 
 if( distCw < distCcw && validCw )
 {
 walkFull.SetShape( l_cw );
 walkP = l_cw.CPoint(-1);
 }
 else if( validCcw )
 {
 walkFull.SetShape( l_ccw );
 walkP = l_ccw.CPoint(-1);
 }
 else
 {
 PNS_DBGN( Dbg(), EndGroup );
 return false;
 }
 
 PNS_DBGN( Dbg(), EndGroup );
 } while( round < 2 && m_placingVia );
 
 
 if( l1.EndsWithVia() )
 {
 VIA v ( l1.Via() );
 v.SetPos( walkFull.CPoint( -1 ) );
 walkFull.AppendVia( v );
 }
 
 PNS_DBG( Dbg(), AddItem, &walkFull, GREEN, 200000, wxT( "walk-full" ) );
 
 if( walkFull.EndsWithVia() )
 {
 PNS_DBG( Dbg(), AddPoint, walkFull.Via().Pos(), GREEN, 200000,
 wxString::Format( "walk-via ok %d", aViaOk ? 1 : 0 ) );
 }
 
 aWalkLine = walkFull;
 
 return !walkFull.EndsWithVia() || aViaOk;
}
 
 
bool LINE_PLACER::rhWalkOnly( const VECTOR2I& aP, LINE& aNewHead, LINE& aNewTail )
{
 LINE walkFull;
 
 int effort = 0;
 bool viaOk = false;
 
 if( ! rhWalkBase( aP, walkFull, ITEM::ANY_T, viaOk ) )
 return false;
 
 switch( Settings().OptimizerEffort() )
 {
 case OE_LOW:
 effort = 0;
 break;
 
 case OE_MEDIUM:
 case OE_FULL:
 effort = OPTIMIZER::MERGE_SEGMENTS;
 break;
 }
 
 DIRECTION_45::CORNER_MODE cornerMode = Settings().GetCornerMode();
 
 // Smart Pads is incompatible with 90-degree mode for now
 if( Settings().SmartPads()
 && ( cornerMode == DIRECTION_45::MITERED_45 || cornerMode == DIRECTION_45::ROUNDED_45 )
 && !m_mouseTrailTracer.IsManuallyForced() )
 {
 effort |= OPTIMIZER::SMART_PADS;
 }
 
 if( m_currentNode->CheckColliding( &walkFull ) )
 {
 PNS_DBG( Dbg(), AddItem, &walkFull, GREEN, 100000, wxString::Format( "collision check fail" ) );
 return false;
 }
 
 // OK, this deserves a bit of explanation. We used to calculate the walk path for the head only,
 // but then the clearance epsilon was added, with the intent of improving collision resolution robustness
 // (now a hull or a walk/shove line cannot collide with the 'owner' of the hull under any circumstances).
 // This, however, introduced a subtle bug. For a row/column/any other 'regular' arrangement
 // of overlapping hulls (think of pads of a SOP/SOIC chip or a regular via grid), walking around may
 // produce a new 'head' that is not considered colliding (due to the clearance epsilon), but with
 // its start point inside one of the subsequent hulls to process.
 // We can't have head[0] inside any hull for the algorithm to work - therefore, we now consider the entire
 // 'tail+head' trace when walking around and in case of success, reconstruct the
 // 'head' and 'tail' by splitting the walk line at a point that is as close as possible to the original
 // head[0], but not inside any obstacle hull.
 //
 // EXECUTIVE SUMMARY: asinine heuristic to make the router get stuck much less often.
 
 if( ! splitHeadTail( walkFull, m_tail, aNewHead, aNewTail ) )
 return false;
 
 if( m_placingVia && viaOk )
 {
 PNS_DBG( Dbg(), AddPoint, aNewHead.CPoint(-1), RED, 1000000, wxString::Format( "VIA" ) );
 
 aNewHead.AppendVia( makeVia( aNewHead.CPoint( -1 ) ) );
 }
 
 OPTIMIZER::Optimize( &aNewHead, effort, m_currentNode );
 
 PNS_DBG( Dbg(), AddItem, &aNewHead, GREEN, 100000, wxString::Format( "walk-new-head" ) );
 PNS_DBG( Dbg(), AddItem, &aNewTail, BLUE, 100000, wxT( "walk-new-tail" ) );
 
 return true;
}
 
 
bool LINE_PLACER::rhMarkObstacles( const VECTOR2I& aP, LINE& aNewHead, LINE& aNewTail )
{
 buildInitialLine( aP, m_head );
 m_head.SetBlockingObstacle( nullptr );
 
 auto obs = m_currentNode->NearestObstacle( &m_head );
 
 // If the head is in colliding state, snap to the hull of the first obstacle.
 // This way, one can route tracks as tightly as possible without enabling
 // the shove/walk mode that certain users find too intrusive.
 if( obs )
 {
 int clearance = m_currentNode->GetClearance( obs->m_item, &m_head, false );
 SHAPE_LINE_CHAIN hull = obs->m_item->Hull( clearance, m_head.Width() );
 VECTOR2I nearest;
 
 DIRECTION_45::CORNER_MODE cornerMode = Settings().GetCornerMode();
 
 if( cornerMode == DIRECTION_45::MITERED_90 || cornerMode == DIRECTION_45::ROUNDED_90 )
 nearest = hull.BBox().ClosestPointTo( aP );
 else
 nearest = hull.NearestPoint( aP );
 
 if( ( nearest - aP ).EuclideanNorm() < m_head.Width() / 2 )
 buildInitialLine( nearest, m_head );
 }
 
 // Note: Something like the below could be used to implement a "stop at first obstacle" mode,
 // but we don't have one right now and there isn't a lot of demand for one. If we do end up
 // doing that, put it in a new routing mode as "highlight collisions" mode should not have
 // collision handling other than highlighting.
#if 0
 if( !Settings().AllowDRCViolations() )
 {
 NODE::OPT_OBSTACLE obs = m_currentNode->NearestObstacle( &m_head );
 
 if( obs && obs->m_distFirst != INT_MAX )
 {
 buildInitialLine( obs->m_ipFirst, m_head );
 m_head.SetBlockingObstacle( obs->m_item );
 }
 }
#endif
 
 aNewHead = m_head;
 aNewTail = m_tail;
 
 return true;
}
 
 
bool LINE_PLACER::splitHeadTail( const LINE& aNewLine, const LINE& aOldTail, LINE& aNewHead,
 LINE& aNewTail )
{
 LINE newTail( aOldTail );
 LINE newHead( aOldTail );
 LINE l2( aNewLine );
 
 newTail.RemoveVia();
 newHead.Clear();
 
 int i;
 bool found = false;
 int n = l2.PointCount();
 
 if( n > 1 && aOldTail.PointCount() > 1 )
 {
 if( l2.CLine().PointOnEdge( aOldTail.CPoint( -1 ) ) )
 {
 l2.Line().Split( aOldTail.CPoint( -1 ) );
 }
 
 for( i = 0; i < aOldTail.PointCount(); i++ )
 {
 if( l2.CLine().Find( aOldTail.CPoint( i ) ) < 0 )
 {
 found = true;
 break;
 }
 }
 
 if( !found )
 i--;
 
 // If the old tail doesn't have any points of the new line, we can't split it.
 if( i >= l2.PointCount() )
 i = l2.PointCount() - 1;
 
 newHead.Clear();
 
 if( i == 0 )
 newTail.Clear();
 else
 newTail.SetShape( l2.CLine().Slice( 0, i ) );
 
 newHead.SetShape( l2.CLine().Slice( i, -1 ) );
 }
 else
 {
 newTail.Clear();
 newHead = l2;
 }
 
 PNS_DBG( Dbg(), AddItem, &newHead, BLUE, 500000, wxT( "head-post-split" ) );
 
 aNewHead = newHead;
 aNewTail = newTail;
 
 return true;
}
 
 
bool LINE_PLACER::rhShoveOnly( const VECTOR2I& aP, LINE& aNewHead, LINE& aNewTail )
{
 LINE walkSolids;
 
 bool viaOk = false;
 
 if( ! rhWalkBase( aP, walkSolids, ITEM::SOLID_T, viaOk ) )
 return false;
 
 m_currentNode = m_shove->CurrentNode();
 
 m_shove->SetLogger( Logger() );
 m_shove->SetDebugDecorator( Dbg() );
 
 if( m_endItem )
 {
 // Make sure the springback algorithm won't erase the NODE that owns m_endItem.
 m_shove->SetSpringbackDoNotTouchNode( static_cast<const NODE*>( m_endItem->Owner() ) );
 }
 
 LINE newHead( walkSolids );
 
 if( walkSolids.EndsWithVia() )
 PNS_DBG( Dbg(), AddPoint, newHead.Via().Pos(), RED, 1000000, wxString::Format( "SVIA [%d]", viaOk?1:0 ) );
 
 if( m_placingVia && viaOk )
 {
 newHead.AppendVia( makeVia( newHead.CPoint( -1 ) ) );
 PNS_DBG( Dbg(), AddPoint, newHead.Via().Pos(), GREEN, 1000000, "shove-new-via" );
 
 }
 
 SHOVE::SHOVE_STATUS status = m_shove->ShoveLines( newHead );
 
 m_currentNode = m_shove->CurrentNode();
 
 int effort = 0;
 
 switch( Settings().OptimizerEffort() )
 {
 case OE_LOW:
 effort = 0;
 break;
 
 case OE_MEDIUM:
 case OE_FULL:
 effort = OPTIMIZER::MERGE_SEGMENTS;
 break;
 }
 
 DIRECTION_45::CORNER_MODE cornerMode = Settings().GetCornerMode();
 
 // Smart Pads is incompatible with 90-degree mode for now
 if( Settings().SmartPads()
 && ( cornerMode == DIRECTION_45::MITERED_45 || cornerMode == DIRECTION_45::ROUNDED_45 )
 && !m_mouseTrailTracer.IsManuallyForced() )
 {
 effort |= OPTIMIZER::SMART_PADS;
 }
 
 if( status == SHOVE::SH_OK || status == SHOVE::SH_HEAD_MODIFIED )
 {
 if( status == SHOVE::SH_HEAD_MODIFIED )
 newHead = m_shove->NewHead();
 
 OPTIMIZER optimizer( m_currentNode );
 
 if( newHead.EndsWithVia() )
 {
 PNS_DBG( Dbg(), AddPoint, newHead.Via().Pos(), GREEN, 1000000, "shove-via-preopt" );
 PNS_DBG( Dbg(), AddPoint, newHead.Via().Pos(), GREEN, 1000000, "shove-via-postopt" );
 }
 
 if( ! splitHeadTail( newHead, m_tail, aNewHead, aNewTail ) )
 return false;
 
 if( newHead.EndsWithVia() )
 aNewHead.AppendVia( newHead.Via() );
 
 optimizer.SetEffortLevel( effort );
 optimizer.SetCollisionMask( ITEM::ANY_T );
 optimizer.Optimize( &aNewHead );
 
 return true;
 }
 else
 {
 return rhWalkOnly( aP, aNewHead, aNewTail );
 }
 
 return false;
}
 
 
bool LINE_PLACER::routeHead( const VECTOR2I& aP, LINE& aNewHead, LINE& aNewTail )
{
 switch( Settings().Mode() )
 {
 case RM_MarkObstacles:
 return rhMarkObstacles( aP, aNewHead, aNewTail );
 case RM_Walkaround:
 return rhWalkOnly( aP, aNewHead, aNewTail );
 case RM_Shove:
 return rhShoveOnly( aP, aNewHead, aNewTail );
 default:
 break;
 }
 
 return false;
}
 
 
bool LINE_PLACER::optimizeTailHeadTransition()
{
 LINE linetmp = Trace();
 
 PNS_DBG( Dbg(), Message, "optimize HT" );
 
 // NOTE: FANOUT_CLEANUP can override posture setting at the moment
 if( !m_mouseTrailTracer.IsManuallyForced() &&
 OPTIMIZER::Optimize( &linetmp, OPTIMIZER::FANOUT_CLEANUP, m_currentNode ) )
 {
 if( linetmp.SegmentCount() < 1 )
 return false;
 
 m_head = linetmp;
 m_direction = DIRECTION_45( linetmp.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.ShapeCount() < 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 ) );
 
 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
 
 PNS_DBG( Dbg(), AddItem, &new_head, LIGHTCYAN, 10000, wxT( "ht-newline" ) );
 
 if( OPTIMIZER::Optimize( &new_head, OPTIMIZER::MERGE_SEGMENTS, m_currentNode ) )
 {
 LINE tmp( m_tail, opt_line );
 
 head.Clear();
 tail.Replace( -threshold, -1, new_head.CLine() );
 tail.Simplify();
 
 m_direction = DIRECTION_45( new_head.CSegment( -1 ) );
 
 return true;
 }
 
 return false;
}
 
void LINE_PLACER::updatePStart( const LINE& tail )
{
 if( tail.CLine().PointCount() )
 m_p_start = tail.CLine().CPoint(-1);
 else
 m_p_start = m_currentStart;
}
 
void LINE_PLACER::routeStep( const VECTOR2I& aP )
{
 bool fail = false;
 bool go_back = false;
 
 int i, n_iter = 1;
 
 
 PNS_DBG( Dbg(), Message, wxString::Format( "routeStep: direction: %s head: %d, tail: %d shapes" ,
 m_direction.Format(),
 m_head.ShapeCount(),
 m_tail.ShapeCount() ) );
 
 PNS_DBG( Dbg(), BeginGroup, wxT( "route-step" ), 0 );
 
 PNS_DBG( Dbg(), AddItem, &m_tail, WHITE, 10000, wxT( "tail-init" ) );
 PNS_DBG( Dbg(), AddItem, &m_head, GREEN, 10000, wxT( "head-init" ) );
 
 for( i = 0; i < n_iter; i++ )
 {
 LINE prevTail( m_tail );
 LINE prevHead( m_head );
 LINE newHead, newTail;
 
 if( !go_back && Settings().FollowMouse() )
 reduceTail( aP );
 
 PNS_DBG( Dbg(), AddItem, &m_tail, WHITE, 10000, wxT( "tail-after-reduce" ) );
 PNS_DBG( Dbg(), AddItem, &m_head, GREEN, 10000, wxT( "head-after-reduce" ) );
 
 go_back = false;
 
 updatePStart( m_tail );
 
 if( !routeHead( aP, newHead, newTail ) )
 {
 m_tail = prevTail;
 m_head = prevHead;
 
 // If we fail to walk out of the initial point (no tail), instead of returning an empty
 // line, return a zero-length line so that the user gets some feedback that routing is
 // happening. This will get pruned later.
 if( m_tail.PointCount() == 0 )
 {
 m_tail.Line().Append( m_p_start );
 m_tail.Line().Append( m_p_start, true );
 }
 
 fail = true;
 }
 
 updatePStart( m_tail );
 
 PNS_DBG( Dbg(), AddItem, &newHead, LIGHTGREEN, 100000, wxString::Format( "new_head [fail: %d]", fail?1:0 ) );
 
 if( fail )
 break;
 
 PNS_DBG( Dbg(), Message, wxString::Format( "N VIA H %d T %d\n", m_head.EndsWithVia() ? 1 : 0, m_tail.EndsWithVia() ? 1 : 0 ) );
 
 m_head = newHead;
 m_tail = newTail;
 
 if( handleSelfIntersections() )
 {
 n_iter++;
 go_back = true;
 }
 
 PNS_DBG( Dbg(), Message, wxString::Format( "SI VIA H %d T %d\n", m_head.EndsWithVia() ? 1 : 0, m_tail.EndsWithVia() ? 1 : 0 ) );
 
 PNS_DBG( Dbg(), AddItem, &m_tail, WHITE, 10000, wxT( "tail-after-si" ) );
 PNS_DBG( Dbg(), AddItem, &m_head, GREEN, 10000, wxT( "head-after-si" ) );
 
 if( !go_back && handlePullback() )
 {
 n_iter++;
 m_head.Clear();
 go_back = true;
 }
 
 PNS_DBG( Dbg(), Message, wxString::Format( "PB VIA H %d T %d\n", m_head.EndsWithVia() ? 1 : 0, m_tail.EndsWithVia() ? 1 : 0 ) );
 
 PNS_DBG( Dbg(), AddItem, &m_tail, WHITE, 100000, wxT( "tail-after-pb" ) );
 PNS_DBG( Dbg(), AddItem, &m_head, GREEN, 100000, wxT( "head-after-pb" ) );
 }
 
 
 if( !fail && Settings().FollowMouse() )
 {
 PNS_DBG( Dbg(), AddItem, &m_tail, WHITE, 10000, wxT( "tail-pre-merge" ) );
 PNS_DBG( Dbg(), AddItem, &m_head, GREEN, 10000, wxT( "head-pre-merge" ) );
 
 if( !optimizeTailHeadTransition() )
 {
 PNS_DBG( Dbg(), Message, wxString::Format( "PreM VIA H %d T %d\n", m_head.EndsWithVia() ? 1 : 0, m_tail.EndsWithVia() ? 1 : 0 ) );
 
 mergeHead();
 
 PNS_DBG( Dbg(), Message, wxString::Format( "PostM VIA H %d T %d\n", m_head.EndsWithVia() ? 1 : 0, m_tail.EndsWithVia() ? 1 : 0 ) );
 }
 
 PNS_DBG( Dbg(), AddItem, &m_tail, WHITE, 100000, wxT( "tail-post-merge" ) );
 PNS_DBG( Dbg(), AddItem, &m_head, GREEN, 100000, wxT( "head-post-merge" ) );
 }
 
 m_last_p_end = aP;
 
 PNS_DBGN( Dbg(), EndGroup );
}
 
 
bool LINE_PLACER::route( const VECTOR2I& aP )
{
 routeStep( aP );
 
 if( !m_head.PointCount() )
 return false;
 
 return m_head.CPoint( -1 ) == aP;
}
 
 
const LINE LINE_PLACER::Trace() const
{
 SHAPE_LINE_CHAIN l( m_tail.CLine() );
 l.Append( m_head.CLine() );
 
 // Only simplify if we have more than two points, because if we have a zero-length seg as the
 // only part of the trace, we don't want it to be removed at this stage (will be the case if
 // the routing start point violates DRC due to track width in shove/walk mode, for example).
 if( l.PointCount() > 2 )
 l.Simplify();
 
 LINE tmp( m_head );
 
 tmp.SetShape( l );
 
 PNS_DBG( Dbg(), AddItem, &m_tail, GREEN, 100000, wxT( "tmp-tail" ) );
 PNS_DBG( Dbg(), AddItem, &m_head, LIGHTGREEN, 100000, wxT( "tmp-head" ) );
 
 return tmp;
}
 
 
const ITEM_SET LINE_PLACER::Traces()
{
 m_currentTrace = Trace();
 return ITEM_SET( &m_currentTrace );
}
 
 
void LINE_PLACER::FlipPosture()
{
 // In order to fix issue 12369 get the current line placer first direction
 // and copy it to the mouse trail tracer, as the current placer may have
 // changed the route.
 if( m_mouseTrailTracer.IsManuallyForced() == false && m_currentTrace.SegmentCount() > 0 )
 {
 DIRECTION_45 firstDirection( m_currentTrace.CSegment( 0 ) );
 
 m_mouseTrailTracer.SetDefaultDirections( firstDirection, DIRECTION_45::UNDEFINED );
 }
 
 m_mouseTrailTracer.FlipPosture();
}
 
 
NODE* LINE_PLACER::CurrentNode( bool aLoopsRemoved ) const
{
 if( aLoopsRemoved && m_lastNode )
 return m_lastNode;
 
 return m_currentNode;
}
 
 
bool LINE_PLACER::SplitAdjacentSegments( NODE* aNode, ITEM* aSeg, const VECTOR2I& aP )
{
 if( !aSeg )
 return false;
 
 if( !aSeg->OfKind( ITEM::SEGMENT_T ) )
 return false;
 
 const JOINT* jt = aNode->FindJoint( aP, aSeg );
 
 if( jt && jt->LinkCount() >= 1 )
 return false;
 
 SEGMENT* s_old = static_cast<SEGMENT*>( aSeg );
 
 std::unique_ptr<SEGMENT> s_new[2] = { Clone( *s_old ), Clone( *s_old ) };
 
 s_new[0]->SetEnds( s_old->Seg().A, aP );
 s_new[1]->SetEnds( aP, s_old->Seg().B );
 
 aNode->Remove( s_old );
 aNode->Add( std::move( s_new[0] ), true );
 aNode->Add( std::move( s_new[1] ), true );
 
 return true;
}
 
 
bool LINE_PLACER::SplitAdjacentArcs( NODE* aNode, ITEM* aArc, const VECTOR2I& aP )
{
 if( !aArc )
 return false;
 
 if( !aArc->OfKind( ITEM::ARC_T ) )
 return false;
 
 const JOINT* jt = aNode->FindJoint( aP, aArc );
 
 if( jt && jt->LinkCount() >= 1 )
 return false;
 
 ARC* a_old = static_cast<ARC*>( aArc );
 const SHAPE_ARC& o_arc = a_old->Arc();
 
 std::unique_ptr<ARC> a_new[2] = { Clone( *a_old ), Clone( *a_old ) };
 
 a_new[0]->Arc().ConstructFromStartEndCenter( o_arc.GetP0(), aP, o_arc.GetCenter(),
 o_arc.IsClockwise(), o_arc.GetWidth() );
 
 a_new[1]->Arc().ConstructFromStartEndCenter( aP, o_arc.GetP1(), o_arc.GetCenter(),
 o_arc.IsClockwise(), o_arc.GetWidth() );
 
 aNode->Remove( a_old );
 aNode->Add( std::move( a_new[0] ), true );
 aNode->Add( std::move( a_new[1] ), true );
 
 return true;
}
 
 
bool LINE_PLACER::SetLayer( int aLayer )
{
 if( m_idle )
 {
 m_currentLayer = aLayer;
 return true;
 }
 else if( m_chainedPlacement )
 {
 return false;
 }
 else if( !m_startItem
 || ( m_startItem->OfKind( ITEM::VIA_T ) && m_startItem->Layers().Overlaps( aLayer ) )
 || ( m_startItem->OfKind( ITEM::SOLID_T ) && m_startItem->Layers().Overlaps( aLayer ) ) )
 {
 m_currentLayer = aLayer;
 m_p_start = m_currentStart;
 m_direction = m_initial_direction;
 m_mouseTrailTracer.Clear();
 m_head.Line().Clear();
 m_tail.Line().Clear();
 m_head.RemoveVia();
 m_tail.RemoveVia();
 m_head.SetLayer( m_currentLayer );
 m_tail.SetLayer( m_currentLayer );
 Move( m_currentEnd, nullptr );
 return true;
 }
 
 return false;
}
 
 
bool LINE_PLACER::Start( const VECTOR2I& aP, ITEM* aStartItem )
{
 m_placementCorrect = false;
 m_currentStart = VECTOR2I( aP );
 m_fixStart = VECTOR2I( aP );
 m_currentEnd = VECTOR2I( aP );
 m_currentNet = aStartItem ? aStartItem->Net() : Router()->GetInterface()->GetOrphanedNetHandle();
 m_startItem = aStartItem;
 m_placingVia = false;
 m_chainedPlacement = false;
 m_fixedTail.Clear();
 m_endItem = nullptr;
 
 setInitialDirection( Settings().InitialDirection() );
 
 initPlacement();
 
 DIRECTION_45 initialDir = m_initial_direction;
 DIRECTION_45 lastSegDir = DIRECTION_45::UNDEFINED;
 
 if( aStartItem && aStartItem->Kind() == ITEM::SEGMENT_T )
 {
 // If we land on a segment endpoint, assume the starting direction is continuing along
 // the same direction as the endpoint. If we started in the middle, don't set a
 // direction so that the posture solver is not biased.
 SEG seg = static_cast<SEGMENT*>( aStartItem )->Seg();
 
 if( aP == seg.A )
 lastSegDir = DIRECTION_45( seg.Reversed() );
 else if( aP == seg.B )
 lastSegDir = DIRECTION_45( seg );
 }
 else if( aStartItem && aStartItem->Kind() == ITEM::SOLID_T &&
 static_cast<SOLID*>( aStartItem )->Parent()->Type() == PCB_PAD_T )
 {
 double angle = static_cast<SOLID*>( aStartItem )->GetOrientation().AsDegrees();
 angle = ( angle + 22.5 ) / 45.0;
 initialDir = DIRECTION_45( static_cast<DIRECTION_45::Directions>( int( angle ) ) );
 }
 
 PNS_DBG( Dbg(), Message, wxString::Format( "Posture: init %s, last seg %s",
 initialDir.Format(), lastSegDir.Format() ) );
 
 m_mouseTrailTracer.Clear();
 m_mouseTrailTracer.AddTrailPoint( aP );
 m_mouseTrailTracer.SetTolerance( m_head.Width() );
 m_mouseTrailTracer.SetDefaultDirections( m_initial_direction, DIRECTION_45::UNDEFINED );
 m_mouseTrailTracer.SetMouseDisabled( !Settings().GetAutoPosture() );
 
 NODE *n;
 
 if ( Settings().Mode() == PNS::RM_Shove )
 n = m_shove->CurrentNode();
 else
 n = m_currentNode;
 
 m_fixedTail.AddStage( m_fixStart, m_currentLayer, m_placingVia, m_direction, n );
 
 return true;
}
 
 
void LINE_PLACER::initPlacement()
{
 m_idle = false;
 
 m_head.Line().Clear();
 m_tail.Line().Clear();
 m_head.SetNet( m_currentNet );
 m_tail.SetNet( m_currentNet );
 m_head.SetLayer( m_currentLayer );
 m_tail.SetLayer( m_currentLayer );
 m_head.SetWidth( m_sizes.TrackWidth() );
 m_tail.SetWidth( m_sizes.TrackWidth() );
 m_head.RemoveVia();
 m_tail.RemoveVia();
 
 m_last_p_end.reset();
 m_p_start = m_currentStart;
 m_direction = m_initial_direction;
 
 NODE* world = Router()->GetWorld();
 
 world->KillChildren();
 NODE* rootNode = world->Branch();
 
 SplitAdjacentSegments( rootNode, m_startItem, m_currentStart );
 
 setWorld( rootNode );
 
 wxLogTrace( wxT( "PNS" ), wxT( "world %p, intitial-direction %s layer %d" ),
 m_world,
 m_direction.Format().c_str(),
 m_currentLayer );
 
 m_lastNode = nullptr;
 m_currentNode = m_world;
 
 m_shove = std::make_unique<SHOVE>( m_world->Branch(), Router() );
}
 
 
bool LINE_PLACER::Move( const VECTOR2I& aP, ITEM* aEndItem )
{
 LINE current;
 int eiDepth = -1;
 
 if( aEndItem && aEndItem->Owner() )
 eiDepth = static_cast<const NODE*>( aEndItem->Owner() )->Depth();
 
 if( m_lastNode )
 {
 delete m_lastNode;
 m_lastNode = nullptr;
 }
 
 m_endItem = aEndItem;
 
 bool reachesEnd = route( aP );
 
 current = Trace();
 
 if( !current.PointCount() )
 m_currentEnd = m_p_start;
 else
 m_currentEnd = current.CLine().CPoint( -1 );
 
 NODE* latestNode = m_currentNode;
 m_lastNode = latestNode->Branch();
 
 if( reachesEnd
 && eiDepth >= 0
 && aEndItem && latestNode->Depth() >= eiDepth
 && current.SegmentCount() )
 {
 if ( aEndItem->Net() == m_currentNet )
 SplitAdjacentSegments( m_lastNode, aEndItem, current.CPoint( -1 ) );
 
 if( Settings().RemoveLoops() )
 removeLoops( m_lastNode, current );
 }
 
 updateLeadingRatLine();
 m_mouseTrailTracer.AddTrailPoint( aP );
 return true;
}
 
 
bool LINE_PLACER::FixRoute( const VECTOR2I& aP, ITEM* aEndItem, bool aForceFinish )
{
 bool fixAll = Settings().GetFixAllSegments();
 bool realEnd = false;
 
 LINE pl = Trace();
 
 if( Settings().Mode() == RM_MarkObstacles )
 {
 // Mark Obstacles is sort of a half-manual, half-automated mode in which the
 // user has more responsibility and authority.
 
 if( aEndItem )
 {
 // The user has indicated a connection should be made. If either the trace or
 // endItem is net-less, then allow the connection by adopting the net of the other.
 if( m_router->GetInterface()->GetNetCode( m_currentNet ) <= 0 )
 {
 m_currentNet = aEndItem->Net();
 pl.SetNet( m_currentNet );
 }
 else if( m_router->GetInterface()->GetNetCode( aEndItem->Net() ) <= 0 )
 {
 aEndItem->SetNet( m_currentNet );
 }
 }
 }
 
 // Collisions still prevent fixing unless "Allow DRC violations" is checked
 // Note that collisions can occur even in walk/shove modes if the beginning of the trace
 // collides (for example if the starting track width is too high).
 
 if( !Settings().AllowDRCViolations() )
 {
 NODE* checkNode = ( Settings().Mode() == RM_Shove ) ? m_shove->CurrentNode() : m_world;
 std::optional<OBSTACLE> obs = checkNode->CheckColliding( &pl );
 
 if( obs )
 {
 // TODO: Determine why the shove node sometimes reports collisions against shoved objects.
 // For now, to work around this issue, we consider only solids in shove mode.
 if( Settings().Mode() != RM_Shove || obs->m_item->OfKind( ITEM::SOLID_T ) )
 return false;
 }
 }
 
 const SHAPE_LINE_CHAIN& l = pl.CLine();
 
 if( !l.SegmentCount() )
 {
 if( m_lastNode )
 {
 // Do a final optimization to the stored state
 NODE::ITEM_VECTOR removed, added;
 m_lastNode->GetUpdatedItems( removed, added );
 
 if( !added.empty() && added.back()->Kind() == ITEM::SEGMENT_T )
 simplifyNewLine( m_lastNode, static_cast<SEGMENT*>( added.back() ) );
 }
 
 // Nothing to commit if we have an empty line
 if( !pl.EndsWithVia() )
 return false;
 
 if( m_lastNode )
 {
 m_lastNode->Add( Clone( pl.Via() ) );
 m_shove->AddLockedSpringbackNode( m_lastNode );
 }
 
 m_currentNode = nullptr;
 
 m_idle = true;
 m_placementCorrect = true;
 return true;
 }
 
 VECTOR2I p_pre_last = l.CPoint( -1 );
 const VECTOR2I p_last = l.CPoint( -1 );
 
 if( l.PointCount() > 2 )
 p_pre_last = l.CPoint( -2 );
 
 if( aEndItem && m_currentNet && m_currentNet == aEndItem->Net() )
 realEnd = true;
 
 if( aForceFinish )
 realEnd = true;
 
 // TODO: Rollback doesn't work properly if fix-all isn't enabled and we are placing arcs,
 // so if we are, act as though we are in fix-all mode.
 if( !fixAll && l.ArcCount() )
 fixAll = true;
 
 // TODO: lastDirSeg will be calculated incorrectly if we end on an arc
 SEG lastDirSeg = ( !fixAll && l.SegmentCount() > 1 ) ? l.CSegment( -2 ) : l.CSegment( -1 );
 DIRECTION_45 d_last( lastDirSeg );
 
 int lastV;
 
 if( realEnd || m_placingVia || fixAll )
 lastV = l.SegmentCount();
 else
 lastV = std::max( 1, l.SegmentCount() - 1 );
 
 ARC arc;
 SEGMENT seg;
 LINKED_ITEM* lastItem = nullptr;
 int lastArc = -1;
 
 for( int i = 0; i < lastV; i++ )
 {
 ssize_t arcIndex = l.ArcIndex( i );
 
 if( arcIndex < 0 || ( lastArc >= 0 && i == lastV - 1 && !l.IsPtOnArc( lastV ) ) )
 {
 seg = SEGMENT( pl.CSegment( i ), m_currentNet );
 seg.SetWidth( pl.Width() );
 seg.SetLayer( m_currentLayer );
 
 std::unique_ptr<SEGMENT> sp = std::make_unique<SEGMENT>( seg );
 lastItem = sp.get();
 
 if( !m_lastNode->Add( std::move( sp ) ) )
 lastItem = nullptr;
 }
 else
 {
 if( arcIndex == lastArc )
 continue;
 
 arc = ARC( l.Arc( arcIndex ), m_currentNet );
 arc.SetWidth( pl.Width() );
 arc.SetLayer( m_currentLayer );
 
 std::unique_ptr<ARC> ap = std::make_unique<ARC>( arc );
 lastItem = ap.get();
 
 if( !m_lastNode->Add( std::move( ap ) ) )
 lastItem = nullptr;
 
 lastArc = arcIndex;
 }
 }
 
 if( pl.EndsWithVia() )
 m_lastNode->Add( Clone( pl.Via() ) );
 
 if( realEnd && lastItem )
 simplifyNewLine( m_lastNode, lastItem );
 
 if( !realEnd )
 {
 setInitialDirection( d_last );
 m_currentStart = ( m_placingVia || fixAll ) ? p_last : p_pre_last;
 
 m_fixedTail.AddStage( m_fixStart, m_currentLayer, m_placingVia, m_direction, m_currentNode );
 
 m_fixStart = m_currentStart;
 m_startItem = nullptr;
 m_placingVia = false;
 m_chainedPlacement = !pl.EndsWithVia();
 
 m_p_start = m_currentStart;
 m_direction = m_initial_direction;
 
 m_head.Line().Clear();
 m_tail.Line().Clear();
 m_head.RemoveVia();
 m_tail.RemoveVia();
 m_currentNode = m_lastNode;
 m_lastNode = m_lastNode->Branch();
 
 m_shove->AddLockedSpringbackNode( m_currentNode );
 
 DIRECTION_45 lastSegDir = pl.EndsWithVia() ? DIRECTION_45::UNDEFINED : d_last;
 
 m_mouseTrailTracer.Clear();
 m_mouseTrailTracer.SetTolerance( m_head.Width() );
 m_mouseTrailTracer.AddTrailPoint( m_currentStart );
 m_mouseTrailTracer.SetDefaultDirections( lastSegDir, DIRECTION_45::UNDEFINED );
 
 m_placementCorrect = true;
 }
 else
 {
 m_shove->AddLockedSpringbackNode( m_lastNode );
 m_placementCorrect = true;
 m_idle = true;
 }
 
 return realEnd;
}
 
 
std::optional<VECTOR2I> LINE_PLACER::UnfixRoute()
{
 FIXED_TAIL::STAGE st;
 std::optional<VECTOR2I> ret;
 
 if ( !m_fixedTail.PopStage( st ) )
 return ret;
 
 if( m_head.Line().PointCount() )
 ret = m_head.Line().CPoint( 0 );
 
 m_head.Line().Clear();
 m_tail.Line().Clear();
 m_startItem = nullptr;
 m_p_start = st.pts[0].p;
 m_fixStart = m_p_start;
 m_direction = st.pts[0].direction;
 m_placingVia = st.pts[0].placingVias;
 m_currentNode = st.commit;
 m_currentLayer = st.pts[0].layer;
 m_currentStart = m_p_start;
 m_head.SetLayer( m_currentLayer );
 m_tail.SetLayer( m_currentLayer );
 m_head.RemoveVia();
 m_tail.RemoveVia();
 
 m_mouseTrailTracer.Clear();
 m_mouseTrailTracer.SetDefaultDirections( m_initial_direction, m_direction );
 m_mouseTrailTracer.AddTrailPoint( m_p_start );
 
 m_shove->RewindSpringbackTo( m_currentNode );
 m_shove->UnlockSpringbackNode( m_currentNode );
 
 if( Settings().Mode() == PNS::RM_Shove )
 {
 m_currentNode = m_shove->CurrentNode();
 m_currentNode->KillChildren();
 }
 
 m_lastNode = m_currentNode->Branch();
 
 return ret;
}
 
 
bool LINE_PLACER::HasPlacedAnything() const
{
 return m_placementCorrect || m_fixedTail.StageCount() > 1;
}
 
 
bool LINE_PLACER::CommitPlacement()
{
 if( Settings().Mode() == PNS::RM_Shove )
 {
 m_shove->RewindToLastLockedNode();
 m_lastNode = m_shove->CurrentNode();
 m_lastNode->KillChildren();
 }
 
 if( m_lastNode )
 Router()->CommitRouting( m_lastNode );
 
 m_lastNode = nullptr;
 m_currentNode = nullptr;
 return true;
}
 
 
void LINE_PLACER::removeLoops( NODE* aNode, LINE& aLatest )
{
 if( !aLatest.SegmentCount() )
 return;
 
 if( aLatest.CLine().CPoint( 0 ) == aLatest.CLine().CPoint( -1 ) )
 return;
 
 std::set<LINKED_ITEM *> toErase;
 aNode->Add( aLatest, true );
 
 for( int s = 0; s < aLatest.LinkCount(); s++ )
 {
 LINKED_ITEM* seg = aLatest.GetLink(s);
 LINE ourLine = aNode->AssembleLine( seg );
 JOINT a, b;
 std::vector<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;
 
 for( LINE& line : lines )
 {
 total++;
 
 if( !( line.ContainsLink( seg ) ) && line.SegmentCount() )
 {
 for( LINKED_ITEM* ss : line.Links() )
 toErase.insert( ss );
 
 removedCount++;
 }
 }
 
 PNS_DBG( Dbg(), Message, wxString::Format( "total segs removed: %d/%d", removedCount, total ) );
 }
 
 for( LINKED_ITEM* s : toErase )
 aNode->Remove( s );
 
 aNode->Remove( aLatest );
}
 
 
void LINE_PLACER::simplifyNewLine( NODE* aNode, LINKED_ITEM* aLatest )
{
 wxASSERT( aLatest->OfKind( ITEM::SEGMENT_T | ITEM::ARC_T ) );
 
 // Before we assemble the final line and run the optimizer, do a separate pass to clean up
 // colinear segments that exist on non-line-corner joints, as these will prevent proper assembly
 // of the line and won't get cleaned up by the optimizer.
 NODE::ITEM_VECTOR removed, added;
 aNode->GetUpdatedItems( removed, added );
 
 std::set<ITEM*> cleanup;
 
 auto processJoint =
 [&]( const JOINT* aJoint, ITEM* aItem )
 {
 if( !aJoint || aJoint->IsLineCorner() )
 return;
 
 SEG refSeg = static_cast<SEGMENT*>( aItem )->Seg();
 
 NODE::ITEM_VECTOR toRemove;
 
 for( ITEM* neighbor : aJoint->CLinks().CItems() )
 {
 if( neighbor == aItem
 || !neighbor->OfKind( ITEM::SEGMENT_T | ITEM::ARC_T )
 || !neighbor->LayersOverlap( aItem ) )
 {
 continue;
 }
 
 if( static_cast<const SEGMENT*>( neighbor )->Width()
 != static_cast<const SEGMENT*>( aItem )->Width() )
 {
 continue;
 }
 
 const SEG& testSeg = static_cast<const SEGMENT*>( neighbor )->Seg();
 
 if( refSeg.Contains( testSeg ) )
 {
 const JOINT* nA = aNode->FindJoint( neighbor->Anchor( 0 ), neighbor );
 const JOINT* nB = aNode->FindJoint( neighbor->Anchor( 1 ), neighbor );
 
 if( ( nA == aJoint && nB->LinkCount() == 1 ) ||
 ( nB == aJoint && nA->LinkCount() == 1 ) )
 {
 cleanup.insert( neighbor );
 }
 }
 }
 };
 
 for( ITEM* item : added )
 {
 if( !item->OfKind( ITEM::SEGMENT_T ) || cleanup.count( item ) )
 continue;
 
 const JOINT* jA = aNode->FindJoint( item->Anchor( 0 ), item );
 const JOINT* jB = aNode->FindJoint( item->Anchor( 1 ), item );
 
 processJoint( jA, item );
 processJoint( jB, item );
 }
 
 for( ITEM* seg : cleanup )
 aNode->Remove( seg );
 
 // And now we can proceed with assembling the final line and optimizing it.
 
 LINE l = aNode->AssembleLine( aLatest );
 
 bool optimized = OPTIMIZER::Optimize( &l, OPTIMIZER::MERGE_COLINEAR, aNode );
 
 SHAPE_LINE_CHAIN simplified( l.CLine() );
 
 simplified.Simplify();
 
 if( optimized || simplified.PointCount() != l.PointCount() )
 {
 aNode->Remove( l );
 l.SetShape( simplified );
 aNode->Add( l );
 }
}
 
 
void LINE_PLACER::UpdateSizes( const SIZES_SETTINGS& aSizes )
{
 m_sizes = aSizes;
 
 if( !m_idle )
 {
 // If the track width continues from an existing track, we don't want to change the width.
 // Disallow changing width after the first segment has been fixed because we don't want to
 // go back and rip up tracks or allow DRC errors
 if( m_sizes.TrackWidthIsExplicit()
 || ( !HasPlacedAnything() && ( !m_startItem || m_startItem->Kind() != ITEM::SEGMENT_T ) ) )
 {
 m_head.SetWidth( m_sizes.TrackWidth() );
 m_tail.SetWidth( m_sizes.TrackWidth() );
 m_currentTrace.SetWidth( m_sizes.TrackWidth() );
 }
 
 if( m_head.EndsWithVia() )
 {
 m_head.SetViaDiameter( m_sizes.ViaDiameter() );
 m_head.SetViaDrill( m_sizes.ViaDrill() );
 }
 }
}
 
 
void LINE_PLACER::updateLeadingRatLine()
{
 LINE current = Trace();
 SHAPE_LINE_CHAIN ratLine;
 TOPOLOGY topo( m_lastNode );
 
 if( topo.LeadingRatLine( &current, ratLine ) )
 m_router->GetInterface()->DisplayRatline( ratLine, m_currentNet );
}
 
 
void LINE_PLACER::SetOrthoMode( bool aOrthoMode )
{
 m_orthoMode = aOrthoMode;
}
 
 
bool LINE_PLACER::buildInitialLine( const VECTOR2I& aP, LINE& aHead, bool aForceNoVia )
{
 SHAPE_LINE_CHAIN l;
 DIRECTION_45 guessedDir = m_mouseTrailTracer.GetPosture( aP );
 
 PNS_DBG( Dbg(), Message, wxString::Format( wxT( "buildInitialLine: m_direction %s, guessedDir %s, tail points %d" ),
 m_direction.Format(), guessedDir.Format(), m_tail.PointCount() ) );
 
 DIRECTION_45::CORNER_MODE cornerMode = Settings().GetCornerMode();
 // Rounded corners don't make sense when routing orthogonally (single track at a time)
 if( m_orthoMode )
 cornerMode = DIRECTION_45::CORNER_MODE::MITERED_45;
 
 PNS_DBG( Dbg(), AddPoint, m_p_start, WHITE, 10000, wxT( "pstart [buildInitial]" ) );
 
 
 if( m_p_start == aP )
 {
 l.Clear();
 }
 else
 {
 if( Settings().GetFreeAngleMode() && Settings().Mode() == RM_MarkObstacles )
 {
 l = SHAPE_LINE_CHAIN( { m_p_start, aP } );
 }
 else
 {
 if( !m_tail.PointCount() )
 l = guessedDir.BuildInitialTrace( m_p_start, aP, false, cornerMode );
 else
 l = m_direction.BuildInitialTrace( m_p_start, aP, false, cornerMode );
 }
 
 if( l.SegmentCount() > 1 && m_orthoMode )
 {
 VECTOR2I newLast = l.CSegment( 0 ).LineProject( l.CPoint( -1 ) );
 
 l.Remove( -1, -1 );
 l.SetPoint( 1, newLast );
 }
 }
 
 aHead.SetLayer( m_currentLayer );
 aHead.SetShape( l );
 
 PNS_DBG( Dbg(), AddItem, &aHead, CYAN, 10000, wxT( "initial-trace" ) );
 
 
 if( !m_placingVia || aForceNoVia )
 return true;
 
 VIA v( makeVia( aP ) );
 v.SetNet( aHead.Net() );
 
 if( Settings().Mode() == RM_MarkObstacles )
 {
 aHead.AppendVia( v );
 return true;
 }
 
 const int collMask = ( Settings().Mode() == RM_Walkaround ) ? ITEM::ANY_T : ITEM::SOLID_T;
 const int iterLimit = Settings().ViaForcePropIterationLimit();
 
 for( int attempt = 0; attempt < 2; attempt++)
 {
 VECTOR2I lead = aP - m_p_start;
 VECTOR2I force;
 
 if( attempt == 1 && m_last_p_end.has_value() )
 lead = aP - m_last_p_end.value();
 
 if( v.PushoutForce( m_currentNode, lead, force, collMask, iterLimit ) )
 {
 SHAPE_LINE_CHAIN line = guessedDir.BuildInitialTrace( m_p_start, aP + force, false, cornerMode );
 aHead = LINE( aHead, line );
 
 v.SetPos( v.Pos() + force );
 
 aHead.AppendVia( v );
 
 PNS_DBG( Dbg(), AddPoint, v.Pos(), GREEN, 1000000, "via-force-coll-2" );
 
 return true;
 }
 }
 
 return false; // via placement unsuccessful
}
 
 
void LINE_PLACER::GetModifiedNets( std::vector<NET_HANDLE>& aNets ) const
{
 aNets.push_back( m_currentNet );
}
 
 
bool LINE_PLACER::AbortPlacement()
{
 m_world->KillChildren();
 return true;
}
 
 
FIXED_TAIL::FIXED_TAIL( int aLineCount )
{
 
}
 
 
FIXED_TAIL::~FIXED_TAIL()
{
 
}
 
 
void FIXED_TAIL::Clear()
{
 m_stages.clear();
}
 
 
void FIXED_TAIL::AddStage( const VECTOR2I& aStart, int aLayer, bool placingVias,
 DIRECTION_45 direction, NODE* aNode )
{
 STAGE st;
 FIX_POINT pt;
 
 pt.p = aStart;
 pt.layer = aLayer;
 pt.direction = direction;
 pt.placingVias = placingVias;
 
 st.pts.push_back(pt);
 st.commit = aNode;
 
 m_stages.push_back( st );
}
 
 
bool FIXED_TAIL::PopStage( FIXED_TAIL::STAGE& aStage )
{
 if( !m_stages.size() )
 return false;
 
 aStage = m_stages.back();
 
 if( m_stages.size() > 1 )
 m_stages.pop_back();
 
 return true;
}
 
 
int FIXED_TAIL::StageCount() const
{
 return m_stages.size();
}
 
}