zone_filler.cpp

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/*
 * This program source code file is part of KiCad, a free EDA CAD application.
 *
 * Copyright (C) 2014-2017 CERN
 * Copyright (C) 2014-2024 KiCad Developers, see AUTHORS.txt for contributors.
 * @author Tomasz Włostowski <[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, 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 <future>
#include <core/kicad_algo.h>
#include <advanced_config.h>
#include <board.h>
#include <board_design_settings.h>
#include <zone.h>
#include <footprint.h>
#include <pad.h>
#include <pcb_target.h>
#include <pcb_track.h>
#include <pcb_text.h>
#include <pcb_textbox.h>
#include <pcb_tablecell.h>
#include <pcb_table.h>
#include <pcb_dimension.h>
#include <connectivity/connectivity_data.h>
#include <convert_basic_shapes_to_polygon.h>
#include <board_commit.h>
#include <progress_reporter.h>
#include <geometry/shape_poly_set.h>
#include <geometry/convex_hull.h>
#include <geometry/geometry_utils.h>
#include <kidialog.h>
#include <core/thread_pool.h>
#include <math/util.h> // for KiROUND
#include "zone_filler.h"
 
 
ZONE_FILLER::ZONE_FILLER( BOARD* aBoard, COMMIT* aCommit ) :
 m_board( aBoard ),
 m_brdOutlinesValid( false ),
 m_commit( aCommit ),
 m_progressReporter( nullptr ),
 m_maxError( ARC_HIGH_DEF ),
 m_worstClearance( 0 )
{
 // To enable add "DebugZoneFiller=1" to kicad_advanced settings file.
 m_debugZoneFiller = ADVANCED_CFG::GetCfg().m_DebugZoneFiller;
}
 
 
ZONE_FILLER::~ZONE_FILLER()
{
}
 
 
void ZONE_FILLER::SetProgressReporter( PROGRESS_REPORTER* aReporter )
{
 m_progressReporter = aReporter;
 wxASSERT_MSG( m_commit, wxT( "ZONE_FILLER must have a valid commit to call "
 "SetProgressReporter" ) );
}
 
 
bool ZONE_FILLER::Fill( const std::vector<ZONE*>& aZones, bool aCheck, wxWindow* aParent )
{
 std::lock_guard<KISPINLOCK> lock( m_board->GetConnectivity()->GetLock() );
 
 std::vector<std::pair<ZONE*, PCB_LAYER_ID>> toFill;
 std::map<std::pair<ZONE*, PCB_LAYER_ID>, MD5_HASH> oldFillHashes;
 std::map<ZONE*, std::map<PCB_LAYER_ID, ISOLATED_ISLANDS>> isolatedIslandsMap;
 
 std::shared_ptr<CONNECTIVITY_DATA> connectivity = m_board->GetConnectivity();
 
 // Rebuild (from scratch, ignoring dirty flags) just in case. This really needs to be reliable.
 connectivity->ClearRatsnest();
 connectivity->Build( m_board, m_progressReporter );
 
 m_worstClearance = m_board->GetMaxClearanceValue();
 
 if( m_progressReporter )
 {
 m_progressReporter->Report( aCheck ? _( "Checking zone fills..." )
 : _( "Building zone fills..." ) );
 m_progressReporter->SetMaxProgress( aZones.size() );
 m_progressReporter->KeepRefreshing();
 }
 
 // The board outlines is used to clip solid areas inside the board (when outlines are valid)
 m_boardOutline.RemoveAllContours();
 m_brdOutlinesValid = m_board->GetBoardPolygonOutlines( m_boardOutline );
 
 // Update and cache zone bounding boxes and pad effective shapes so that we don't have to
 // make them thread-safe.
 //
 for( ZONE* zone : m_board->Zones() )
 zone->CacheBoundingBox();
 
 for( FOOTPRINT* footprint : m_board->Footprints() )
 {
 for( PAD* pad : footprint->Pads() )
 {
 if( pad->IsDirty() )
 {
 pad->BuildEffectiveShapes( UNDEFINED_LAYER );
 pad->BuildEffectivePolygon( ERROR_OUTSIDE );
 }
 }
 
 for( ZONE* zone : footprint->Zones() )
 zone->CacheBoundingBox();
 
 // Rules may depend on insideCourtyard() or other expressions
 footprint->BuildCourtyardCaches();
 }
 
 LSET boardCuMask = m_board->GetEnabledLayers() & LSET::AllCuMask();
 
 auto findHighestPriorityZone = [&]( const BOX2I& aBBox, const PCB_LAYER_ID aItemLayer,
 const int aNetcode,
 const std::function<bool( const ZONE* )> aTestFn ) -> ZONE*
 {
 unsigned highestPriority = 0;
 ZONE* highestPriorityZone = nullptr;
 
 for( ZONE* zone : m_board->Zones() )
 {
 // Rule areas are not filled
 if( zone->GetIsRuleArea() )
 continue;
 
 if( zone->GetAssignedPriority() < highestPriority )
 continue;
 
 if( !zone->IsOnLayer( aItemLayer ) )
 continue;
 
 // Degenerate zones will cause trouble; skip them
 if( zone->GetNumCorners() <= 2 )
 continue;
 
 if( !zone->GetBoundingBox().Intersects( aBBox ) )
 continue;
 
 if( !aTestFn( zone ) )
 continue;
 
 // Prefer highest priority and matching netcode
 if( zone->GetAssignedPriority() > highestPriority || zone->GetNetCode() == aNetcode )
 {
 highestPriority = zone->GetAssignedPriority();
 highestPriorityZone = zone;
 }
 }
 
 return highestPriorityZone;
 };
 
 auto isInPourKeepoutArea = [&]( const BOX2I& aBBox, const PCB_LAYER_ID aItemLayer,
 const VECTOR2I aTestPoint ) -> bool
 {
 for( ZONE* zone : m_board->Zones() )
 {
 if( !zone->GetIsRuleArea() )
 continue;
 
 if( !zone->GetDoNotAllowCopperPour() )
 continue;
 
 if( !zone->IsOnLayer( aItemLayer ) )
 continue;
 
 // Degenerate zones will cause trouble; skip them
 if( zone->GetNumCorners() <= 2 )
 continue;
 
 if( !zone->GetBoundingBox().Intersects( aBBox ) )
 continue;
 
 if( zone->Outline()->Contains( aTestPoint ) )
 return true;
 }
 
 return false;
 };
 
 // Determine state of conditional via flashing
 for( PCB_TRACK* track : m_board->Tracks() )
 {
 if( track->Type() == PCB_VIA_T )
 {
 PCB_VIA* via = static_cast<PCB_VIA*>( track );
 
 via->ClearZoneLayerOverrides();
 
 if( !via->GetRemoveUnconnected() )
 continue;
 
 BOX2I bbox = via->GetBoundingBox();
 VECTOR2I center = via->GetPosition();
 int testRadius = via->GetDrillValue() / 2 + 1;
 unsigned netcode = via->GetNetCode();
 LSET layers = via->GetLayerSet() & boardCuMask;
 
 // Checking if the via hole touches the zone outline
 auto viaTestFn = [&]( const ZONE* aZone ) -> bool
 {
 return aZone->Outline()->Contains( center, -1, testRadius );
 };
 
 for( PCB_LAYER_ID layer : layers.Seq() )
 {
 if( !via->ConditionallyFlashed( layer ) )
 continue;
 
 if( isInPourKeepoutArea( bbox, layer, center ) )
 {
 via->SetZoneLayerOverride( layer, ZLO_FORCE_NO_ZONE_CONNECTION );
 }
 else
 {
 ZONE* zone = findHighestPriorityZone( bbox, layer, netcode, viaTestFn );
 
 if( zone && zone->GetNetCode() == via->GetNetCode() )
 via->SetZoneLayerOverride( layer, ZLO_FORCE_FLASHED );
 else
 via->SetZoneLayerOverride( layer, ZLO_FORCE_NO_ZONE_CONNECTION );
 }
 }
 }
 }
 
 // Determine state of conditional pad flashing
 for( FOOTPRINT* footprint : m_board->Footprints() )
 {
 for( PAD* pad : footprint->Pads() )
 {
 pad->ClearZoneLayerOverrides();
 
 if( !pad->GetRemoveUnconnected() )
 continue;
 
 BOX2I bbox = pad->GetBoundingBox();
 VECTOR2I center = pad->GetPosition();
 unsigned netcode = pad->GetNetCode();
 LSET layers = pad->GetLayerSet() & boardCuMask;
 
 auto padTestFn = [&]( const ZONE* aZone ) -> bool
 {
 return aZone->Outline()->Contains( center );
 };
 
 for( PCB_LAYER_ID layer : layers.Seq() )
 {
 if( !pad->ConditionallyFlashed( layer ) )
 continue;
 
 if( isInPourKeepoutArea( bbox, layer, center ) )
 {
 pad->SetZoneLayerOverride( layer, ZLO_FORCE_NO_ZONE_CONNECTION );
 }
 else
 {
 ZONE* zone = findHighestPriorityZone( bbox, layer, netcode, padTestFn );
 
 if( zone && zone->GetNetCode() == pad->GetNetCode() )
 pad->SetZoneLayerOverride( layer, ZLO_FORCE_FLASHED );
 else
 pad->SetZoneLayerOverride( layer, ZLO_FORCE_NO_ZONE_CONNECTION );
 }
 }
 }
 }
 
 for( ZONE* zone : aZones )
 {
 // Rule areas are not filled
 if( zone->GetIsRuleArea() )
 continue;
 
 // Degenerate zones will cause trouble; skip them
 if( zone->GetNumCorners() <= 2 )
 continue;
 
 if( m_commit )
 m_commit->Modify( zone );
 
 // calculate the hash value for filled areas. it will be used later to know if the
 // current filled areas are up to date
 for( PCB_LAYER_ID layer : zone->GetLayerSet().Seq() )
 {
 zone->BuildHashValue( layer );
 oldFillHashes[ { zone, layer } ] = zone->GetHashValue( layer );
 
 // Add the zone to the list of zones to test or refill
 toFill.emplace_back( std::make_pair( zone, layer ) );
 
 isolatedIslandsMap[ zone ][ layer ] = ISOLATED_ISLANDS();
 }
 
 // Remove existing fill first to prevent drawing invalid polygons on some platforms
 zone->UnFill();
 }
 
 auto check_fill_dependency =
 [&]( ZONE* aZone, PCB_LAYER_ID aLayer, ZONE* aOtherZone ) -> bool
 {
 // Check to see if we have to knock-out the filled areas of a higher-priority
 // zone. If so we have to wait until said zone is filled before we can fill.
 
 // If the other zone is already filled on the requested layer then we're
 // good-to-go
 if( aOtherZone->GetFillFlag( aLayer ) )
 return false;
 
 // Even if keepouts exclude copper pours, the exclusion is by outline rather than
 // filled area, so we're good-to-go here too
 if( aOtherZone->GetIsRuleArea() )
 return false;
 
 // If the other zone is never going to be filled then don't wait for it
 if( aOtherZone->GetNumCorners() <= 2 )
 return false;
 
 // If the zones share no common layers
 if( !aOtherZone->GetLayerSet().test( aLayer ) )
 return false;
 
 if( aZone->HigherPriority( aOtherZone ) )
 return false;
 
 // Same-net zones always use outlines to produce determinate results
 if( aOtherZone->SameNet( aZone ) )
 return false;
 
 // A higher priority zone is found: if we intersect and it's not filled yet
 // then we have to wait.
 BOX2I inflatedBBox = aZone->GetBoundingBox();
 inflatedBBox.Inflate( m_worstClearance );
 
 if( !inflatedBBox.Intersects( aOtherZone->GetBoundingBox() ) )
 return false;
 
 return aZone->Outline()->Collide( aOtherZone->Outline(), m_worstClearance );
 };
 
 auto fill_lambda =
 [&]( std::pair<ZONE*, PCB_LAYER_ID> aFillItem ) -> int
 {
 PCB_LAYER_ID layer = aFillItem.second;
 ZONE* zone = aFillItem.first;
 bool canFill = true;
 
 // Check for any fill dependencies. If our zone needs to be clipped by
 // another zone then we can't fill until that zone is filled.
 for( ZONE* otherZone : aZones )
 {
 if( otherZone == zone )
 continue;
 
 if( check_fill_dependency( zone, layer, otherZone ) )
 {
 canFill = false;
 break;
 }
 }
 
 if( m_progressReporter && m_progressReporter->IsCancelled() )
 return 0;
 
 if( !canFill )
 return 0;
 
 // Now we're ready to fill.
 {
 std::unique_lock<std::mutex> zoneLock( zone->GetLock(), std::try_to_lock );
 
 if( !zoneLock.owns_lock() )
 return 0;
 
 SHAPE_POLY_SET fillPolys;
 
 if( !fillSingleZone( zone, layer, fillPolys ) )
 return 0;
 
 zone->SetFilledPolysList( layer, fillPolys );
 }
 
 if( m_progressReporter )
 m_progressReporter->AdvanceProgress();
 
 return 1;
 };
 
 auto tesselate_lambda =
 [&]( std::pair<ZONE*, PCB_LAYER_ID> aFillItem ) -> int
 {
 if( m_progressReporter && m_progressReporter->IsCancelled() )
 return 0;
 
 PCB_LAYER_ID layer = aFillItem.second;
 ZONE* zone = aFillItem.first;
 
 {
 std::unique_lock<std::mutex> zoneLock( zone->GetLock(), std::try_to_lock );
 
 if( !zoneLock.owns_lock() )
 return 0;
 
 zone->CacheTriangulation( layer );
 zone->SetFillFlag( layer, true );
 }
 
 return 1;
 };
 
 // Calculate the copper fills (NB: this is multi-threaded)
 //
 std::vector<std::pair<std::future<int>, int>> returns;
 returns.reserve( toFill.size() );
 size_t finished = 0;
 bool cancelled = false;
 
 thread_pool& tp = GetKiCadThreadPool();
 
 for( const std::pair<ZONE*, PCB_LAYER_ID>& fillItem : toFill )
 returns.emplace_back( std::make_pair( tp.submit( fill_lambda, fillItem ), 0 ) );
 
 while( !cancelled && finished != 2 * toFill.size() )
 {
 for( size_t ii = 0; ii < returns.size(); ++ii )
 {
 auto& ret = returns[ii];
 
 if( ret.second > 1 )
 continue;
 
 std::future_status status = ret.first.wait_for( std::chrono::seconds( 0 ) );
 
 if( status == std::future_status::ready )
 {
 if( ret.first.get() ) // lambda completed
 {
 ++finished;
 ret.second++; // go to next step
 }
 
 if( !cancelled )
 {
 // Queue the next step (will re-queue the existing step if it didn't complete)
 if( ret.second == 0 )
 returns[ii].first = tp.submit( fill_lambda, toFill[ii] );
 else if( ret.second == 1 )
 returns[ii].first = tp.submit( tesselate_lambda, toFill[ii] );
 }
 }
 }
 
 std::this_thread::sleep_for( std::chrono::milliseconds( 100 ) );
 
 
 if( m_progressReporter )
 {
 m_progressReporter->KeepRefreshing();
 
 if( m_progressReporter->IsCancelled() )
 cancelled = true;
 }
 }
 
 // Make sure that all futures have finished.
 // This can happen when the user cancels the above operation
 for( auto& ret : returns )
 {
 if( ret.first.valid() )
 {
 std::future_status status = ret.first.wait_for( std::chrono::seconds( 0 ) );
 
 while( status != std::future_status::ready )
 {
 if( m_progressReporter )
 m_progressReporter->KeepRefreshing();
 
 status = ret.first.wait_for( std::chrono::milliseconds( 100 ) );
 }
 }
 }
 
 // Now update the connectivity to check for isolated copper islands
 // (NB: FindIsolatedCopperIslands() is multi-threaded)
 //
 if( m_progressReporter )
 {
 if( m_progressReporter->IsCancelled() )
 return false;
 
 m_progressReporter->AdvancePhase();
 m_progressReporter->Report( _( "Removing isolated copper islands..." ) );
 m_progressReporter->KeepRefreshing();
 }
 
 connectivity->SetProgressReporter( m_progressReporter );
 connectivity->FillIsolatedIslandsMap( isolatedIslandsMap );
 connectivity->SetProgressReporter( nullptr );
 
 if( m_progressReporter && m_progressReporter->IsCancelled() )
 return false;
 
 for( ZONE* zone : aZones )
 {
 // Keepout zones are not filled
 if( zone->GetIsRuleArea() )
 continue;
 
 zone->SetIsFilled( true );
 }
 
 // Now remove isolated copper islands according to the isolated islands strategy assigned
 // by the user (always, never, below-certain-size).
 //
 for( const auto& [ zone, zoneIslands ] : isolatedIslandsMap )
 {
 // If *all* the polygons are islands, do not remove any of them
 bool allIslands = true;
 
 for( const auto& [ layer, layerIslands ] : zoneIslands )
 {
 if( layerIslands.m_IsolatedOutlines.size()
 != static_cast<size_t>( zone->GetFilledPolysList( layer )->OutlineCount() ) )
 {
 allIslands = false;
 break;
 }
 }
 
 if( allIslands )
 continue;
 
 for( const auto& [ layer, layerIslands ] : zoneIslands )
 {
 if( m_debugZoneFiller && LSET::InternalCuMask().Contains( layer ) )
 continue;
 
 if( layerIslands.m_IsolatedOutlines.empty() )
 continue;
 
 std::vector<int> islands = layerIslands.m_IsolatedOutlines;
 
 // The list of polygons to delete must be explored from last to first in list,
 // to allow deleting a polygon from list without breaking the remaining of the list
 std::sort( islands.begin(), islands.end(), std::greater<int>() );
 
 std::shared_ptr<SHAPE_POLY_SET> poly = zone->GetFilledPolysList( layer );
 long long int minArea = zone->GetMinIslandArea();
 ISLAND_REMOVAL_MODE mode = zone->GetIslandRemovalMode();
 
 for( int idx : islands )
 {
 SHAPE_LINE_CHAIN& outline = poly->Outline( idx );
 
 if( mode == ISLAND_REMOVAL_MODE::ALWAYS )
 poly->DeletePolygonAndTriangulationData( idx, false );
 else if ( mode == ISLAND_REMOVAL_MODE::AREA && outline.Area( true ) < minArea )
 poly->DeletePolygonAndTriangulationData( idx, false );
 else
 zone->SetIsIsland( layer, idx );
 }
 
 poly->UpdateTriangulationDataHash();
 zone->CalculateFilledArea();
 
 if( m_progressReporter && m_progressReporter->IsCancelled() )
 return false;
 }
 }
 
 // Now remove islands which are either outside the board edge or fail to meet the minimum
 // area requirements
 using island_check_return = std::vector<std::pair<std::shared_ptr<SHAPE_POLY_SET>, int>>;
 
 std::vector<std::pair<std::shared_ptr<SHAPE_POLY_SET>, double>> polys_to_check;
 
 // rough estimate to save re-allocation time
 polys_to_check.reserve( m_board->GetCopperLayerCount() * aZones.size() );
 
 for( ZONE* zone : aZones )
 {
 // Don't check for connections on layers that only exist in the zone but
 // were disabled in the board
 BOARD* board = zone->GetBoard();
 LSET zoneCopperLayers = zone->GetLayerSet() & LSET::AllCuMask() & board->GetEnabledLayers();
 
 // Min-thickness is the web thickness. On the other hand, a blob min-thickness by
 // min-thickness is not useful. Since there's no obvious definition of web vs. blob, we
 // arbitrarily choose "at least 3X the area".
 double minArea = (double) zone->GetMinThickness() * zone->GetMinThickness() * 3;
 
 for( PCB_LAYER_ID layer : zoneCopperLayers.Seq() )
 {
 if( m_debugZoneFiller && LSET::InternalCuMask().Contains( layer ) )
 continue;
 
 polys_to_check.emplace_back( zone->GetFilledPolysList( layer ), minArea );
 }
 }
 
 auto island_lambda =
 [&]( int aStart, int aEnd ) -> island_check_return
 {
 island_check_return retval;
 
 for( int ii = aStart; ii < aEnd && !cancelled; ++ii )
 {
 auto [poly, minArea] = polys_to_check[ii];
 
 for( int jj = poly->OutlineCount() - 1; jj >= 0; jj-- )
 {
 SHAPE_POLY_SET island;
 SHAPE_POLY_SET intersection;
 const SHAPE_LINE_CHAIN& test_poly = poly->Polygon( jj ).front();
 double island_area = test_poly.Area();
 
 if( island_area < minArea )
 continue;
 
 
 island.AddOutline( test_poly );
 intersection.BooleanIntersection( m_boardOutline, island,
 SHAPE_POLY_SET::POLYGON_MODE::PM_FAST );
 
 // Nominally, all of these areas should be either inside or outside the
 // board outline. So this test should be able to just compare areas (if
 // they are equal, you are inside). But in practice, we sometimes have
 // slight overlap at the edges, so testing against half-size area acts as
 // a fail-safe.
 if( intersection.Area() < island_area / 2.0 )
 retval.emplace_back( poly, jj );
 }
 }
 
 return retval;
 };
 
 auto island_returns = tp.parallelize_loop( 0, polys_to_check.size(), island_lambda );
 cancelled = false;
 
 // Allow island removal threads to finish
 for( size_t ii = 0; ii < island_returns.size(); ++ii )
 {
 std::future<island_check_return>& ret = island_returns[ii];
 
 if( ret.valid() )
 {
 std::future_status status = ret.wait_for( std::chrono::seconds( 0 ) );
 
 while( status != std::future_status::ready )
 {
 if( m_progressReporter )
 {
 m_progressReporter->KeepRefreshing();
 
 if( m_progressReporter->IsCancelled() )
 cancelled = true;
 }
 
 status = ret.wait_for( std::chrono::milliseconds( 100 ) );
 }
 }
 }
 
 if( cancelled )
 return false;
 
 for( size_t ii = 0; ii < island_returns.size(); ++ii )
 {
 std::future<island_check_return>& ret = island_returns[ii];
 
 if( ret.valid() )
 {
 for( auto& action_item : ret.get() )
 action_item.first->DeletePolygonAndTriangulationData( action_item.second, true );
 }
 }
 
 for( ZONE* zone : aZones )
 zone->CalculateFilledArea();
 
 
 if( aCheck )
 {
 bool outOfDate = false;
 
 for( ZONE* zone : aZones )
 {
 // Keepout zones are not filled
 if( zone->GetIsRuleArea() )
 continue;
 
 for( PCB_LAYER_ID layer : zone->GetLayerSet().Seq() )
 {
 zone->BuildHashValue( layer );
 
 if( oldFillHashes[ { zone, layer } ] != zone->GetHashValue( layer ) )
 outOfDate = true;
 }
 }
 
 if( outOfDate )
 {
 KIDIALOG dlg( aParent, _( "Zone fills are out-of-date. Refill?" ),
 _( "Confirmation" ), wxOK | wxCANCEL | wxICON_WARNING );
 dlg.SetOKCancelLabels( _( "Refill" ), _( "Continue without Refill" ) );
 dlg.DoNotShowCheckbox( __FILE__, __LINE__ );
 
 if( dlg.ShowModal() == wxID_CANCEL )
 return false;
 }
 else
 {
 // No need to commit something that hasn't changed (and committing will set
 // the modified flag).
 return false;
 }
 }
 
 if( m_progressReporter )
 {
 if( m_progressReporter->IsCancelled() )
 return false;
 
 m_progressReporter->AdvancePhase();
 m_progressReporter->KeepRefreshing();
 }
 
 return true;
}
 
 
void ZONE_FILLER::addKnockout( PAD* aPad, PCB_LAYER_ID aLayer, int aGap, SHAPE_POLY_SET& aHoles )
{
 if( aPad->GetShape() == PAD_SHAPE::CUSTOM )
 {
 SHAPE_POLY_SET poly;
 aPad->TransformShapeToPolygon( poly, aLayer, aGap, m_maxError, ERROR_OUTSIDE );
 
 // the pad shape in zone can be its convex hull or the shape itself
 if( aPad->GetCustomShapeInZoneOpt() == PADSTACK::CUSTOM_SHAPE_ZONE_MODE::CONVEXHULL )
 {
 std::vector<VECTOR2I> convex_hull;
 BuildConvexHull( convex_hull, poly );
 
 aHoles.NewOutline();
 
 for( const VECTOR2I& pt : convex_hull )
 aHoles.Append( pt );
 }
 else
 aHoles.Append( poly );
 }
 else
 {
 aPad->TransformShapeToPolygon( aHoles, aLayer, aGap, m_maxError, ERROR_OUTSIDE );
 }
}
 
 
void ZONE_FILLER::addHoleKnockout( PAD* aPad, int aGap, SHAPE_POLY_SET& aHoles )
{
 aPad->TransformHoleToPolygon( aHoles, aGap, m_maxError, ERROR_OUTSIDE );
}
 
 
void ZONE_FILLER::addKnockout( BOARD_ITEM* aItem, PCB_LAYER_ID aLayer, int aGap,
 bool aIgnoreLineWidth, SHAPE_POLY_SET& aHoles )
{
 switch( aItem->Type() )
 {
 case PCB_FIELD_T:
 case PCB_TEXT_T:
 {
 PCB_TEXT* text = static_cast<PCB_TEXT*>( aItem );
 
 if( text->IsVisible() )
 {
 if( text->IsKnockout() )
 {
 // Knockout text should only leave holes where the text is, not where the copper fill
 // around it would be.
 PCB_TEXT textCopy = *text;
 textCopy.SetIsKnockout( false );
 textCopy.TransformShapeToPolygon( aHoles, aLayer, 0, m_maxError, ERROR_OUTSIDE );
 }
 else
 {
 text->TransformShapeToPolygon( aHoles, aLayer, aGap, m_maxError, ERROR_OUTSIDE );
 }
 }
 
 break;
 }
 
 case PCB_TEXTBOX_T:
 case PCB_TABLE_T:
 case PCB_SHAPE_T:
 case PCB_TARGET_T:
 aItem->TransformShapeToPolygon( aHoles, aLayer, aGap, m_maxError, ERROR_OUTSIDE,
 aIgnoreLineWidth );
 break;
 
 case PCB_DIM_ALIGNED_T:
 case PCB_DIM_LEADER_T:
 case PCB_DIM_CENTER_T:
 case PCB_DIM_RADIAL_T:
 case PCB_DIM_ORTHOGONAL_T:
 {
 PCB_DIMENSION_BASE* dim = static_cast<PCB_DIMENSION_BASE*>( aItem );
 
 dim->TransformShapeToPolygon( aHoles, aLayer, aGap, m_maxError, ERROR_OUTSIDE, false );
 dim->PCB_TEXT::TransformShapeToPolygon( aHoles, aLayer, aGap, m_maxError, ERROR_OUTSIDE );
 break;
 }
 
 default:
 break;
 }
}
 
 
void ZONE_FILLER::knockoutThermalReliefs( const ZONE* aZone, PCB_LAYER_ID aLayer,
 SHAPE_POLY_SET& aFill,
 std::vector<PAD*>& aThermalConnectionPads,
 std::vector<PAD*>& aNoConnectionPads )
{
 BOARD_DESIGN_SETTINGS& bds = m_board->GetDesignSettings();
 ZONE_CONNECTION connection;
 DRC_CONSTRAINT constraint;
 int padClearance;
 int holeClearance;
 SHAPE_POLY_SET holes;
 
 for( FOOTPRINT* footprint : m_board->Footprints() )
 {
 for( PAD* pad : footprint->Pads() )
 {
 BOX2I padBBox = pad->GetBoundingBox();
 padBBox.Inflate( m_worstClearance );
 
 if( !padBBox.Intersects( aZone->GetBoundingBox() ) )
 continue;
 
 bool noConnection = pad->GetNetCode() != aZone->GetNetCode();
 
 if( !aZone->IsTeardropArea() )
 {
 if( aZone->GetNetCode() == 0
 || pad->GetZoneLayerOverride( aLayer ) == ZLO_FORCE_NO_ZONE_CONNECTION )
 {
 noConnection = true;
 }
 }
 
 if( noConnection )
 {
 // collect these for knockout in buildCopperItemClearances()
 aNoConnectionPads.push_back( pad );
 continue;
 }
 
 if( aZone->IsTeardropArea() )
 {
 connection = ZONE_CONNECTION::FULL;
 }
 else
 {
 constraint = bds.m_DRCEngine->EvalZoneConnection( pad, aZone, aLayer );
 connection = constraint.m_ZoneConnection;
 }
 
 switch( connection )
 {
 case ZONE_CONNECTION::THERMAL:
 constraint = bds.m_DRCEngine->EvalRules( THERMAL_RELIEF_GAP_CONSTRAINT, pad, aZone,
 aLayer );
 padClearance = constraint.GetValue().Min();
 
 if( pad->CanFlashLayer( aLayer ) )
 {
 aThermalConnectionPads.push_back( pad );
 addKnockout( pad, aLayer, padClearance, holes );
 }
 else if( pad->GetDrillSize().x > 0 )
 {
 pad->TransformHoleToPolygon( holes, padClearance, m_maxError, ERROR_OUTSIDE );
 }
 
 break;
 
 case ZONE_CONNECTION::NONE:
 constraint = bds.m_DRCEngine->EvalRules( PHYSICAL_CLEARANCE_CONSTRAINT, pad,
 aZone, aLayer );
 
 if( constraint.GetValue().Min() > aZone->GetLocalClearance().value() )
 padClearance = constraint.GetValue().Min();
 else
 padClearance = aZone->GetLocalClearance().value();
 
 if( pad->FlashLayer( aLayer ) )
 {
 addKnockout( pad, aLayer, padClearance, holes );
 }
 else if( pad->GetDrillSize().x > 0 )
 {
 constraint = bds.m_DRCEngine->EvalRules( PHYSICAL_HOLE_CLEARANCE_CONSTRAINT,
 pad, aZone, aLayer );
 
 if( constraint.GetValue().Min() > padClearance )
 holeClearance = constraint.GetValue().Min();
 else
 holeClearance = padClearance;
 
 pad->TransformHoleToPolygon( holes, holeClearance, m_maxError, ERROR_OUTSIDE );
 }
 
 break;
 
 default:
 // No knockout
 continue;
 }
 }
 }
 
 aFill.BooleanSubtract( holes, SHAPE_POLY_SET::PM_FAST );
}
 
 
void ZONE_FILLER::buildCopperItemClearances( const ZONE* aZone, PCB_LAYER_ID aLayer,
 const std::vector<PAD*>& aNoConnectionPads,
 SHAPE_POLY_SET& aHoles )
{
 BOARD_DESIGN_SETTINGS& bds = m_board->GetDesignSettings();
 long ticker = 0;
 
 auto checkForCancel =
 [&ticker]( PROGRESS_REPORTER* aReporter ) -> bool
 {
 return aReporter && ( ticker++ % 50 ) == 0 && aReporter->IsCancelled();
 };
 
 // A small extra clearance to be sure actual track clearances are not smaller than
 // requested clearance due to many approximations in calculations, like arc to segment
 // approx, rounding issues, etc.
 BOX2I zone_boundingbox = aZone->GetBoundingBox();
 int extra_margin = pcbIUScale.mmToIU( ADVANCED_CFG::GetCfg().m_ExtraClearance );
 
 // Items outside the zone bounding box are skipped, so it needs to be inflated by the
 // largest clearance value found in the netclasses and rules
 zone_boundingbox.Inflate( m_worstClearance + extra_margin );
 
 auto evalRulesForItems =
 [&bds]( DRC_CONSTRAINT_T aConstraint, const BOARD_ITEM* a, const BOARD_ITEM* b,
 PCB_LAYER_ID aEvalLayer ) -> int
 {
 DRC_CONSTRAINT c = bds.m_DRCEngine->EvalRules( aConstraint, a, b, aEvalLayer );
 
 if( c.IsNull() )
 return -1;
 else
 return c.GetValue().Min();
 };
 
 // Add non-connected pad clearances
 //
 auto knockoutPadClearance =
 [&]( PAD* aPad )
 {
 int init_gap = evalRulesForItems( PHYSICAL_CLEARANCE_CONSTRAINT, aZone, aPad, aLayer );
 int gap = init_gap;
 bool hasHole = aPad->GetDrillSize().x > 0;
 bool flashLayer = aPad->FlashLayer( aLayer );
 bool platedHole = hasHole && aPad->GetAttribute() == PAD_ATTRIB::PTH;
 
 if( flashLayer || platedHole )
 {
 gap = std::max( gap, evalRulesForItems( CLEARANCE_CONSTRAINT,
 aZone, aPad, aLayer ) );
 }
 
 if( flashLayer && gap >= 0 )
 addKnockout( aPad, aLayer, gap + extra_margin, aHoles );
 
 if( hasHole )
 {
 // NPTH do not need copper clearance gaps to their holes
 if( aPad->GetAttribute() == PAD_ATTRIB::NPTH )
 gap = init_gap;
 
 gap = std::max( gap, evalRulesForItems( PHYSICAL_HOLE_CLEARANCE_CONSTRAINT,
 aZone, aPad, aLayer ) );
 
 gap = std::max( gap, evalRulesForItems( HOLE_CLEARANCE_CONSTRAINT,
 aZone, aPad, aLayer ) );
 
 if( gap >= 0 )
 addHoleKnockout( aPad, gap + extra_margin, aHoles );
 }
 };
 
 for( PAD* pad : aNoConnectionPads )
 {
 if( checkForCancel( m_progressReporter ) )
 return;
 
 knockoutPadClearance( pad );
 }
 
 // Add non-connected track clearances
 //
 auto knockoutTrackClearance =
 [&]( PCB_TRACK* aTrack )
 {
 if( aTrack->GetBoundingBox().Intersects( zone_boundingbox ) )
 {
 bool sameNet = aTrack->GetNetCode() == aZone->GetNetCode();
 
 if( !aZone->IsTeardropArea() && aZone->GetNetCode() == 0 )
 sameNet = false;
 
 int gap = evalRulesForItems( PHYSICAL_CLEARANCE_CONSTRAINT,
 aZone, aTrack, aLayer );
 
 if( aTrack->Type() == PCB_VIA_T )
 {
 PCB_VIA* via = static_cast<PCB_VIA*>( aTrack );
 
 if( via->GetZoneLayerOverride( aLayer ) == ZLO_FORCE_NO_ZONE_CONNECTION )
 sameNet = false;
 }
 
 if( !sameNet )
 {
 gap = std::max( gap, evalRulesForItems( CLEARANCE_CONSTRAINT,
 aZone, aTrack, aLayer ) );
 }
 
 if( aTrack->Type() == PCB_VIA_T )
 {
 PCB_VIA* via = static_cast<PCB_VIA*>( aTrack );
 
 if( via->FlashLayer( aLayer ) && gap > 0 )
 {
 via->TransformShapeToPolygon( aHoles, aLayer, gap + extra_margin,
 m_maxError, ERROR_OUTSIDE );
 }
 
 gap = std::max( gap, evalRulesForItems( PHYSICAL_HOLE_CLEARANCE_CONSTRAINT,
 aZone, via, aLayer ) );
 
 if( !sameNet )
 {
 gap = std::max( gap, evalRulesForItems( HOLE_CLEARANCE_CONSTRAINT,
 aZone, via, aLayer ) );
 }
 
 if( gap >= 0 )
 {
 int radius = via->GetDrillValue() / 2;
 
 TransformCircleToPolygon( aHoles, via->GetPosition(),
 radius + gap + extra_margin,
 m_maxError, ERROR_OUTSIDE );
 }
 }
 else
 {
 if( gap >= 0 )
 {
 aTrack->TransformShapeToPolygon( aHoles, aLayer, gap + extra_margin,
 m_maxError, ERROR_OUTSIDE );
 }
 }
 }
 };
 
 for( PCB_TRACK* track : m_board->Tracks() )
 {
 if( !track->IsOnLayer( aLayer ) )
 continue;
 
 if( checkForCancel( m_progressReporter ) )
 return;
 
 knockoutTrackClearance( track );
 }
 
 // Add graphic item clearances.
 //
 auto knockoutGraphicClearance =
 [&]( BOARD_ITEM* aItem )
 {
 int shapeNet = -1;
 
 if( aItem->Type() == PCB_SHAPE_T )
 shapeNet = static_cast<PCB_SHAPE*>( aItem )->GetNetCode();
 
 bool sameNet = shapeNet == aZone->GetNetCode();
 
 if( !aZone->IsTeardropArea() && aZone->GetNetCode() == 0 )
 sameNet = false;
 
 // A item on the Edge_Cuts or Margin is always seen as on any layer:
 if( aItem->IsOnLayer( aLayer )
 || aItem->IsOnLayer( Edge_Cuts )
 || aItem->IsOnLayer( Margin ) )
 {
 if( aItem->GetBoundingBox().Intersects( zone_boundingbox ) )
 {
 bool ignoreLineWidths = false;
 int gap = evalRulesForItems( PHYSICAL_CLEARANCE_CONSTRAINT,
 aZone, aItem, aLayer );
 
 if( aItem->IsOnLayer( aLayer ) && !sameNet )
 {
 gap = std::max( gap, evalRulesForItems( CLEARANCE_CONSTRAINT,
 aZone, aItem, aLayer ) );
 }
 else if( aItem->IsOnLayer( Edge_Cuts ) )
 {
 gap = std::max( gap, evalRulesForItems( EDGE_CLEARANCE_CONSTRAINT,
 aZone, aItem, aLayer ) );
 ignoreLineWidths = true;
 }
 else if( aItem->IsOnLayer( Margin ) )
 {
 gap = std::max( gap, evalRulesForItems( EDGE_CLEARANCE_CONSTRAINT,
 aZone, aItem, aLayer ) );
 }
 
 if( gap >= 0 )
 {
 gap += extra_margin;
 addKnockout( aItem, aLayer, gap, ignoreLineWidths, aHoles );
 }
 }
 }
 };
 
 auto knockoutCourtyardClearance =
 [&]( FOOTPRINT* aFootprint )
 {
 if( aFootprint->GetBoundingBox().Intersects( zone_boundingbox ) )
 {
 int gap = evalRulesForItems( PHYSICAL_CLEARANCE_CONSTRAINT, aZone,
 aFootprint, aLayer );
 
 if( gap == 0 )
 {
 aHoles.Append( aFootprint->GetCourtyard( aLayer ) );
 }
 else if( gap > 0 )
 {
 SHAPE_POLY_SET hole = aFootprint->GetCourtyard( aLayer );
 hole.Inflate( gap, CORNER_STRATEGY::ROUND_ALL_CORNERS, m_maxError );
 aHoles.Append( hole );
 }
 }
 };
 
 for( FOOTPRINT* footprint : m_board->Footprints() )
 {
 knockoutCourtyardClearance( footprint );
 knockoutGraphicClearance( &footprint->Reference() );
 knockoutGraphicClearance( &footprint->Value() );
 
 std::set<PAD*> allowedNetTiePads;
 
 // Don't knock out holes for graphic items which implement a net-tie to the zone's net
 // on the layer being filled.
 if( footprint->IsNetTie() )
 {
 for( PAD* pad : footprint->Pads() )
 {
 bool sameNet = pad->GetNetCode() == aZone->GetNetCode();
 
 if( !aZone->IsTeardropArea() && aZone->GetNetCode() == 0 )
 sameNet = false;
 
 if( sameNet )
 {
 if( pad->IsOnLayer( aLayer ) )
 allowedNetTiePads.insert( pad );
 
 for( PAD* other : footprint->GetNetTiePads( pad ) )
 {
 if( other->IsOnLayer( aLayer ) )
 allowedNetTiePads.insert( other );
 }
 }
 }
 }
 
 for( BOARD_ITEM* item : footprint->GraphicalItems() )
 {
 if( checkForCancel( m_progressReporter ) )
 return;
 
 BOX2I itemBBox = item->GetBoundingBox();
 
 if( !zone_boundingbox.Intersects( itemBBox ) )
 continue;
 
 bool skipItem = false;
 
 if( item->IsOnLayer( aLayer ) )
 {
 std::shared_ptr<SHAPE> itemShape = item->GetEffectiveShape();
 
 for( PAD* pad : allowedNetTiePads )
 {
 if( pad->GetBoundingBox().Intersects( itemBBox )
 && pad->GetEffectiveShape()->Collide( itemShape.get() ) )
 {
 skipItem = true;
 break;
 }
 }
 }
 
 if( !skipItem )
 knockoutGraphicClearance( item );
 }
 }
 
 for( BOARD_ITEM* item : m_board->Drawings() )
 {
 if( checkForCancel( m_progressReporter ) )
 return;
 
 knockoutGraphicClearance( item );
 }
 
 // Add non-connected zone clearances
 //
 auto knockoutZoneClearance =
 [&]( ZONE* aKnockout )
 {
 // If the zones share no common layers
 if( !aKnockout->GetLayerSet().test( aLayer ) )
 return;
 
 if( aKnockout->GetBoundingBox().Intersects( zone_boundingbox ) )
 {
 if( aKnockout->GetIsRuleArea() )
 {
 // Keepouts use outline with no clearance
 aKnockout->TransformSmoothedOutlineToPolygon( aHoles, 0, m_maxError,
 ERROR_OUTSIDE, nullptr );
 }
 else
 {
 int gap = std::max( 0, evalRulesForItems( PHYSICAL_CLEARANCE_CONSTRAINT,
 aZone, aKnockout, aLayer ) );
 
 gap = std::max( gap, evalRulesForItems( CLEARANCE_CONSTRAINT,
 aZone, aKnockout, aLayer ) );
 
 SHAPE_POLY_SET poly;
 aKnockout->TransformShapeToPolygon( poly, aLayer, gap + extra_margin,
 m_maxError, ERROR_OUTSIDE );
 aHoles.Append( poly );
 }
 }
 };
 
 for( ZONE* otherZone : m_board->Zones() )
 {
 if( checkForCancel( m_progressReporter ) )
 return;
 
 // Negative clearance permits zones to short
 if( evalRulesForItems( CLEARANCE_CONSTRAINT, aZone, otherZone, aLayer ) < 0 )
 continue;
 
 if( otherZone->GetIsRuleArea() )
 {
 if( otherZone->GetDoNotAllowCopperPour() && !aZone->IsTeardropArea() )
 knockoutZoneClearance( otherZone );
 }
 else if( otherZone->HigherPriority( aZone ) )
 {
 if( !otherZone->SameNet( aZone ) )
 knockoutZoneClearance( otherZone );
 }
 }
 
 for( FOOTPRINT* footprint : m_board->Footprints() )
 {
 for( ZONE* otherZone : footprint->Zones() )
 {
 if( checkForCancel( m_progressReporter ) )
 return;
 
 if( otherZone->GetIsRuleArea() )
 {
 if( otherZone->GetDoNotAllowCopperPour() && !aZone->IsTeardropArea() )
 knockoutZoneClearance( otherZone );
 }
 else if( otherZone->HigherPriority( aZone ) )
 {
 if( !otherZone->SameNet( aZone ) )
 knockoutZoneClearance( otherZone );
 }
 }
 }
 
 aHoles.Simplify( SHAPE_POLY_SET::PM_FAST );
}
 
 
void ZONE_FILLER::subtractHigherPriorityZones( const ZONE* aZone, PCB_LAYER_ID aLayer,
 SHAPE_POLY_SET& aRawFill )
{
 BOX2I zoneBBox = aZone->GetBoundingBox();
 
 auto knockoutZoneOutline =
 [&]( ZONE* aKnockout )
 {
 // If the zones share no common layers
 if( !aKnockout->GetLayerSet().test( aLayer ) )
 return;
 
 if( aKnockout->GetBoundingBox().Intersects( zoneBBox ) )
 {
 // Processing of arc shapes in zones is not yet supported because Clipper
 // can't do boolean operations on them. The poly outline must be converted to
 // segments first.
 SHAPE_POLY_SET outline = aKnockout->Outline()->CloneDropTriangulation();
 outline.ClearArcs();
 
 aRawFill.BooleanSubtract( outline, SHAPE_POLY_SET::PM_FAST );
 }
 };
 
 for( ZONE* otherZone : m_board->Zones() )
 {
 // Don't use the `HigherPriority()` check here because we _only_ want to knock out zones
 // with explicitly higher priorities, not those with equal priorities
 if( otherZone->SameNet( aZone )
 && otherZone->GetAssignedPriority() > aZone->GetAssignedPriority() )
 {
 // Do not remove teardrop area: it is not useful and not good
 if( !otherZone->IsTeardropArea() )
 knockoutZoneOutline( otherZone );
 }
 }
 
 for( FOOTPRINT* footprint : m_board->Footprints() )
 {
 for( ZONE* otherZone : footprint->Zones() )
 {
 if( otherZone->SameNet( aZone ) && otherZone->HigherPriority( aZone ) )
 {
 // Do not remove teardrop area: it is not useful and not good
 if( !otherZone->IsTeardropArea() )
 knockoutZoneOutline( otherZone );
 }
 }
 }
}
 
 
#define DUMP_POLYS_TO_COPPER_LAYER( a, b, c ) \
 { if( m_debugZoneFiller && aDebugLayer == b ) \
 { \
 m_board->SetLayerName( b, c ); \
 SHAPE_POLY_SET d = a; \
 d.Fracture( SHAPE_POLY_SET::PM_STRICTLY_SIMPLE ); \
 aFillPolys = d; \
 return false; \
 } \
 }
 
 
bool ZONE_FILLER::fillCopperZone( const ZONE* aZone, PCB_LAYER_ID aLayer, PCB_LAYER_ID aDebugLayer,
 const SHAPE_POLY_SET& aSmoothedOutline,
 const SHAPE_POLY_SET& aMaxExtents, SHAPE_POLY_SET& aFillPolys )
{
 m_maxError = m_board->GetDesignSettings().m_MaxError;
 
 // Features which are min_width should survive pruning; features that are *less* than
 // min_width should not. Therefore we subtract epsilon from the min_width when
 // deflating/inflating.
 int half_min_width = aZone->GetMinThickness() / 2;
 int epsilon = pcbIUScale.mmToIU( 0.001 );
 
 // Solid polygons are deflated and inflated during calculations. Deflating doesn't cause
 // issues, but inflate is tricky as it can create excessively long and narrow spikes for
 // acute angles.
 // ALLOW_ACUTE_CORNERS cannot be used due to the spike problem.
 // CHAMFER_ACUTE_CORNERS is tempting, but can still produce spikes in some unusual
 // circumstances (https://gitlab.com/kicad/code/kicad/-/issues/5581).
 // It's unclear if ROUND_ACUTE_CORNERS would have the same issues, but is currently avoided
 // as a "less-safe" option.
 // ROUND_ALL_CORNERS produces the uniformly nicest shapes, but also a lot of segments.
 // CHAMFER_ALL_CORNERS improves the segment count.
 CORNER_STRATEGY fastCornerStrategy = CORNER_STRATEGY::CHAMFER_ALL_CORNERS;
 CORNER_STRATEGY cornerStrategy = CORNER_STRATEGY::ROUND_ALL_CORNERS;
 
 std::vector<PAD*> thermalConnectionPads;
 std::vector<PAD*> noConnectionPads;
 std::deque<SHAPE_LINE_CHAIN> thermalSpokes;
 SHAPE_POLY_SET clearanceHoles;
 
 aFillPolys = aSmoothedOutline;
 DUMP_POLYS_TO_COPPER_LAYER( aFillPolys, In1_Cu, wxT( "smoothed-outline" ) );
 
 if( m_progressReporter && m_progressReporter->IsCancelled() )
 return false;
 
 /* -------------------------------------------------------------------------------------
 * Knockout thermal reliefs.
 */
 
 knockoutThermalReliefs( aZone, aLayer, aFillPolys, thermalConnectionPads, noConnectionPads );
 DUMP_POLYS_TO_COPPER_LAYER( aFillPolys, In2_Cu, wxT( "minus-thermal-reliefs" ) );
 
 if( m_progressReporter && m_progressReporter->IsCancelled() )
 return false;
 
 /* -------------------------------------------------------------------------------------
 * Knockout electrical clearances.
 */
 
 buildCopperItemClearances( aZone, aLayer, noConnectionPads, clearanceHoles );
 DUMP_POLYS_TO_COPPER_LAYER( clearanceHoles, In3_Cu, wxT( "clearance-holes" ) );
 
 if( m_progressReporter && m_progressReporter->IsCancelled() )
 return false;
 
 /* -------------------------------------------------------------------------------------
 * Add thermal relief spokes.
 */
 
 buildThermalSpokes( aZone, aLayer, thermalConnectionPads, thermalSpokes );
 
 if( m_progressReporter && m_progressReporter->IsCancelled() )
 return false;
 
 // Create a temporary zone that we can hit-test spoke-ends against. It's only temporary
 // because the "real" subtract-clearance-holes has to be done after the spokes are added.
 static const bool USE_BBOX_CACHES = true;
 SHAPE_POLY_SET testAreas = aFillPolys.CloneDropTriangulation();
 testAreas.BooleanSubtract( clearanceHoles, SHAPE_POLY_SET::PM_FAST );
 DUMP_POLYS_TO_COPPER_LAYER( testAreas, In4_Cu, wxT( "minus-clearance-holes" ) );
 
 // Prune features that don't meet minimum-width criteria
 if( half_min_width - epsilon > epsilon )
 {
 testAreas.Deflate( half_min_width - epsilon, fastCornerStrategy, m_maxError );
 DUMP_POLYS_TO_COPPER_LAYER( testAreas, In5_Cu, wxT( "spoke-test-deflated" ) );
 
 testAreas.Inflate( half_min_width - epsilon, fastCornerStrategy, m_maxError );
 DUMP_POLYS_TO_COPPER_LAYER( testAreas, In6_Cu, wxT( "spoke-test-reinflated" ) );
 }
 
 if( m_progressReporter && m_progressReporter->IsCancelled() )
 return false;
 
 // Spoke-end-testing is hugely expensive so we generate cached bounding-boxes to speed
 // things up a bit.
 testAreas.BuildBBoxCaches();
 int interval = 0;
 
 SHAPE_POLY_SET debugSpokes;
 
 for( const SHAPE_LINE_CHAIN& spoke : thermalSpokes )
 {
 const VECTOR2I& testPt = spoke.CPoint( 3 );
 
 // Hit-test against zone body
 if( testAreas.Contains( testPt, -1, 1, USE_BBOX_CACHES ) )
 {
 if( m_debugZoneFiller )
 debugSpokes.AddOutline( spoke );
 
 aFillPolys.AddOutline( spoke );
 continue;
 }
 
 if( interval++ > 400 )
 {
 if( m_progressReporter && m_progressReporter->IsCancelled() )
 return false;
 
 interval = 0;
 }
 
 // Hit-test against other spokes
 for( const SHAPE_LINE_CHAIN& other : thermalSpokes )
 {
 // Hit test in both directions to avoid interactions with round-off errors.
 // (See https://gitlab.com/kicad/code/kicad/-/issues/13316.)
 if( &other != &spoke
 && other.PointInside( testPt, 1, USE_BBOX_CACHES )
 && spoke.PointInside( other.CPoint( 3 ), 1, USE_BBOX_CACHES ) )
 {
 if( m_debugZoneFiller )
 debugSpokes.AddOutline( spoke );
 
 aFillPolys.AddOutline( spoke );
 break;
 }
 }
 }
 
 DUMP_POLYS_TO_COPPER_LAYER( debugSpokes, In7_Cu, wxT( "spokes" ) );
 
 if( m_progressReporter && m_progressReporter->IsCancelled() )
 return false;
 
 aFillPolys.BooleanSubtract( clearanceHoles, SHAPE_POLY_SET::PM_FAST );
 DUMP_POLYS_TO_COPPER_LAYER( aFillPolys, In8_Cu, wxT( "after-spoke-trimming" ) );
 
 /* -------------------------------------------------------------------------------------
 * Prune features that don't meet minimum-width criteria
 */
 
 if( half_min_width - epsilon > epsilon )
 aFillPolys.Deflate( half_min_width - epsilon, fastCornerStrategy, m_maxError );
 
 // Min-thickness is the web thickness. On the other hand, a blob min-thickness by
 // min-thickness is not useful. Since there's no obvious definition of web vs. blob, we
 // arbitrarily choose "at least 2X min-thickness on one axis". (Since we're doing this
 // during the deflated state, that means we test for "at least min-thickness".)
 for( int ii = aFillPolys.OutlineCount() - 1; ii >= 0; ii-- )
 {
 std::vector<SHAPE_LINE_CHAIN>& island = aFillPolys.Polygon( ii );
 BOX2I islandExtents;
 
 for( const VECTOR2I& pt : island.front().CPoints() )
 {
 islandExtents.Merge( pt );
 
 if( islandExtents.GetSizeMax() > aZone->GetMinThickness() )
 break;
 }
 
 if( islandExtents.GetSizeMax() < aZone->GetMinThickness() )
 aFillPolys.DeletePolygon( ii );
 }
 
 DUMP_POLYS_TO_COPPER_LAYER( aFillPolys, In9_Cu, wxT( "deflated" ) );
 
 if( m_progressReporter && m_progressReporter->IsCancelled() )
 return false;
 
 /* -------------------------------------------------------------------------------------
 * Process the hatch pattern (note that we do this while deflated)
 */
 
 if( aZone->GetFillMode() == ZONE_FILL_MODE::HATCH_PATTERN )
 {
 if( !addHatchFillTypeOnZone( aZone, aLayer, aDebugLayer, aFillPolys ) )
 return false;
 }
 
 if( m_progressReporter && m_progressReporter->IsCancelled() )
 return false;
 
 /* -------------------------------------------------------------------------------------
 * Finish minimum-width pruning by re-inflating
 */
 
 if( half_min_width - epsilon > epsilon )
 aFillPolys.Inflate( half_min_width - epsilon, cornerStrategy, m_maxError, true );
 
 DUMP_POLYS_TO_COPPER_LAYER( aFillPolys, In15_Cu, wxT( "after-reinflating" ) );
 
 /* -------------------------------------------------------------------------------------
 * Ensure additive changes (thermal stubs and inflating acute corners) do not add copper
 * outside the zone boundary, inside the clearance holes, or between otherwise isolated
 * islands
 */
 
 for( PAD* pad : thermalConnectionPads )
 addHoleKnockout( pad, 0, clearanceHoles );
 
 aFillPolys.BooleanIntersection( aMaxExtents, SHAPE_POLY_SET::PM_FAST );
 DUMP_POLYS_TO_COPPER_LAYER( aFillPolys, In16_Cu, wxT( "after-trim-to-outline" ) );
 aFillPolys.BooleanSubtract( clearanceHoles, SHAPE_POLY_SET::PM_FAST );
 DUMP_POLYS_TO_COPPER_LAYER( aFillPolys, In17_Cu, wxT( "after-trim-to-clearance-holes" ) );
 
 /* -------------------------------------------------------------------------------------
 * Lastly give any same-net but higher-priority zones control over their own area.
 */
 
 subtractHigherPriorityZones( aZone, aLayer, aFillPolys );
 DUMP_POLYS_TO_COPPER_LAYER( aFillPolys, In18_Cu, wxT( "minus-higher-priority-zones" ) );
 
 aFillPolys.Fracture( SHAPE_POLY_SET::PM_FAST );
 return true;
}
 
 
bool ZONE_FILLER::fillNonCopperZone( const ZONE* aZone, PCB_LAYER_ID aLayer,
 const SHAPE_POLY_SET& aSmoothedOutline,
 SHAPE_POLY_SET& aFillPolys )
{
 BOARD_DESIGN_SETTINGS& bds = m_board->GetDesignSettings();
 BOX2I zone_boundingbox = aZone->GetBoundingBox();
 SHAPE_POLY_SET clearanceHoles;
 long ticker = 0;
 
 auto checkForCancel =
 [&ticker]( PROGRESS_REPORTER* aReporter ) -> bool
 {
 return aReporter && ( ticker++ % 50 ) == 0 && aReporter->IsCancelled();
 };
 
 auto knockoutGraphicClearance =
 [&]( BOARD_ITEM* aItem )
 {
 if( aItem->IsKnockout() && aItem->IsOnLayer( aLayer )
 && aItem->GetBoundingBox().Intersects( zone_boundingbox ) )
 {
 DRC_CONSTRAINT cc = bds.m_DRCEngine->EvalRules( PHYSICAL_CLEARANCE_CONSTRAINT,
 aZone, aItem, aLayer );
 
 addKnockout( aItem, aLayer, cc.GetValue().Min(), false, clearanceHoles );
 }
 };
 
 for( FOOTPRINT* footprint : m_board->Footprints() )
 {
 if( checkForCancel( m_progressReporter ) )
 return false;
 
 knockoutGraphicClearance( &footprint->Reference() );
 knockoutGraphicClearance( &footprint->Value() );
 
 for( BOARD_ITEM* item : footprint->GraphicalItems() )
 knockoutGraphicClearance( item );
 }
 
 for( BOARD_ITEM* item : m_board->Drawings() )
 {
 if( checkForCancel( m_progressReporter ) )
 return false;
 
 knockoutGraphicClearance( item );
 }
 
 aFillPolys = aSmoothedOutline;
 aFillPolys.BooleanSubtract( clearanceHoles, SHAPE_POLY_SET::PM_FAST );
 
 for( ZONE* keepout : m_board->Zones() )
 {
 if( !keepout->GetIsRuleArea() )
 continue;
 
 if( keepout->GetDoNotAllowCopperPour() && keepout->IsOnLayer( aLayer ) )
 {
 if( keepout->GetBoundingBox().Intersects( zone_boundingbox ) )
 aFillPolys.BooleanSubtract( *keepout->Outline(), SHAPE_POLY_SET::PM_FAST );
 }
 }
 
 // Features which are min_width should survive pruning; features that are *less* than
 // min_width should not. Therefore we subtract epsilon from the min_width when
 // deflating/inflating.
 int half_min_width = aZone->GetMinThickness() / 2;
 int epsilon = pcbIUScale.mmToIU( 0.001 );
 
 aFillPolys.Deflate( half_min_width - epsilon, CORNER_STRATEGY::CHAMFER_ALL_CORNERS, m_maxError );
 
 // Remove the non filled areas due to the hatch pattern
 if( aZone->GetFillMode() == ZONE_FILL_MODE::HATCH_PATTERN )
 {
 if( !addHatchFillTypeOnZone( aZone, aLayer, aLayer, aFillPolys ) )
 return false;
 }
 
 // Re-inflate after pruning of areas that don't meet minimum-width criteria
 if( half_min_width - epsilon > epsilon )
 aFillPolys.Inflate( half_min_width - epsilon, CORNER_STRATEGY::ROUND_ALL_CORNERS, m_maxError );
 
 aFillPolys.Fracture( SHAPE_POLY_SET::PM_STRICTLY_SIMPLE );
 return true;
}
 
 
/*
 * Build the filled solid areas data from real outlines (stored in m_Poly)
 * The solid areas can be more than one on copper layers, and do not have holes
 * ( holes are linked by overlapping segments to the main outline)
 */
bool ZONE_FILLER::fillSingleZone( ZONE* aZone, PCB_LAYER_ID aLayer, SHAPE_POLY_SET& aFillPolys )
{
 SHAPE_POLY_SET* boardOutline = m_brdOutlinesValid ? &m_boardOutline : nullptr;
 SHAPE_POLY_SET maxExtents;
 SHAPE_POLY_SET smoothedPoly;
 PCB_LAYER_ID debugLayer = UNDEFINED_LAYER;
 
 if( m_debugZoneFiller && LSET::InternalCuMask().Contains( aLayer ) )
 {
 debugLayer = aLayer;
 aLayer = F_Cu;
 }
 
 if( !aZone->BuildSmoothedPoly( maxExtents, aLayer, boardOutline, &smoothedPoly ) )
 return false;
 
 if( m_progressReporter && m_progressReporter->IsCancelled() )
 return false;
 
 if( aZone->IsOnCopperLayer() )
 {
 if( fillCopperZone( aZone, aLayer, debugLayer, smoothedPoly, maxExtents, aFillPolys ) )
 aZone->SetNeedRefill( false );
 }
 else
 {
 if( fillNonCopperZone( aZone, aLayer, smoothedPoly, aFillPolys ) )
 aZone->SetNeedRefill( false );
 }
 
 return true;
}
 
 
void ZONE_FILLER::buildThermalSpokes( const ZONE* aZone, PCB_LAYER_ID aLayer,
 const std::vector<PAD*>& aSpokedPadsList,
 std::deque<SHAPE_LINE_CHAIN>& aSpokesList )
{
 BOARD_DESIGN_SETTINGS& bds = m_board->GetDesignSettings();
 BOX2I zoneBB = aZone->GetBoundingBox();
 DRC_CONSTRAINT constraint;
 
 zoneBB.Inflate( std::max( bds.GetBiggestClearanceValue(), aZone->GetLocalClearance().value() ) );
 
 // Is a point on the boundary of the polygon inside or outside? The boundary may be off by
 // MaxError, and we add 1.5 mil for some wiggle room.
 int epsilon = KiROUND( bds.m_MaxError + pcbIUScale.IU_PER_MM * 0.038 ); // 1.5 mil
 
 for( PAD* pad : aSpokedPadsList )
 {
 // We currently only connect to pads, not pad holes
 if( !pad->IsOnLayer( aLayer ) )
 continue;
 
 constraint = bds.m_DRCEngine->EvalRules( THERMAL_RELIEF_GAP_CONSTRAINT, pad, aZone, aLayer );
 int thermalReliefGap = constraint.GetValue().Min();
 
 constraint = bds.m_DRCEngine->EvalRules( THERMAL_SPOKE_WIDTH_CONSTRAINT, pad, aZone, aLayer );
 int spoke_w = constraint.GetValue().Opt();
 
 // Spoke width should ideally be smaller than the pad minor axis.
 // Otherwise the thermal shape is not really a thermal relief,
 // and the algo to count the actual number of spokes can fail
 int spoke_max_allowed_w = std::min( pad->GetSize().x, pad->GetSize().y );
 
 spoke_w = std::max( spoke_w, constraint.Value().Min() );
 spoke_w = std::min( spoke_w, constraint.Value().Max() );
 
 // ensure the spoke width is smaller than the pad minor size
 spoke_w = std::min( spoke_w, spoke_max_allowed_w );
 
 // Cannot create stubs having a width < zone min thickness
 if( spoke_w < aZone->GetMinThickness() )
 continue;
 
 int spoke_half_w = spoke_w / 2;
 
 // Quick test here to possibly save us some work
 BOX2I itemBB = pad->GetBoundingBox();
 itemBB.Inflate( thermalReliefGap + epsilon );
 
 if( !( itemBB.Intersects( zoneBB ) ) )
 continue;
 
 bool customSpokes = false;
 
 if( pad->GetShape() == PAD_SHAPE::CUSTOM )
 {
 for( const std::shared_ptr<PCB_SHAPE>& primitive : pad->GetPrimitives() )
 {
 if( primitive->IsProxyItem() && primitive->GetShape() == SHAPE_T::SEGMENT )
 {
 customSpokes = true;
 break;
 }
 }
 }
 
 // Thermal spokes consist of square-ended segments from the pad center to points just
 // outside the thermal relief. The outside end has an extra center point (which must be
 // at idx 3) which is used for testing whether or not the spoke connects to copper in the
 // parent zone.
 
 auto buildSpokesFromOrigin =
 [&]( const BOX2I& box )
 {
 for( int i = 0; i < 4; i++ )
 {
 SHAPE_LINE_CHAIN spoke;
 
 switch( i )
 {
 case 0: // lower stub
 spoke.Append( +spoke_half_w, -spoke_half_w );
 spoke.Append( -spoke_half_w, -spoke_half_w );
 spoke.Append( -spoke_half_w, box.GetBottom() );
 spoke.Append( 0, box.GetBottom() ); // test pt
 spoke.Append( +spoke_half_w, box.GetBottom() );
 break;
 
 case 1: // upper stub
 spoke.Append( +spoke_half_w, +spoke_half_w );
 spoke.Append( -spoke_half_w, +spoke_half_w );
 spoke.Append( -spoke_half_w, box.GetTop() );
 spoke.Append( 0, box.GetTop() ); // test pt
 spoke.Append( +spoke_half_w, box.GetTop() );
 break;
 
 case 2: // right stub
 spoke.Append( -spoke_half_w, +spoke_half_w );
 spoke.Append( -spoke_half_w, -spoke_half_w );
 spoke.Append( box.GetRight(), -spoke_half_w );
 spoke.Append( box.GetRight(), 0 ); // test pt
 spoke.Append( box.GetRight(), +spoke_half_w );
 break;
 
 case 3: // left stub
 spoke.Append( +spoke_half_w, +spoke_half_w );
 spoke.Append( +spoke_half_w, -spoke_half_w );
 spoke.Append( box.GetLeft(), -spoke_half_w );
 spoke.Append( box.GetLeft(), 0 ); // test pt
 spoke.Append( box.GetLeft(), +spoke_half_w );
 break;
 }
 
 spoke.SetClosed( true );
 aSpokesList.push_back( std::move( spoke ) );
 }
 };
 
 if( customSpokes )
 {
 SHAPE_POLY_SET thermalPoly;
 SHAPE_LINE_CHAIN thermalOutline;
 
 pad->TransformShapeToPolygon( thermalPoly, aLayer, thermalReliefGap + epsilon,
 m_maxError, ERROR_OUTSIDE );
 
 if( thermalPoly.OutlineCount() )
 thermalOutline = thermalPoly.Outline( 0 );
 
 for( const std::shared_ptr<PCB_SHAPE>& primitive : pad->GetPrimitives() )
 {
 if( primitive->IsProxyItem() && primitive->GetShape() == SHAPE_T::SEGMENT )
 {
 SEG seg( primitive->GetStart(), primitive->GetEnd() );
 SHAPE_LINE_CHAIN::INTERSECTIONS intersections;
 
 RotatePoint( seg.A, pad->GetOrientation() );
 RotatePoint( seg.B, pad->GetOrientation() );
 seg.A += pad->ShapePos();
 seg.B += pad->ShapePos();
 
 // Make sure seg.A is the origin
 if( !pad->GetEffectivePolygon( ERROR_OUTSIDE )->Contains( seg.A ) )
 seg.Reverse();
 
 // Trim seg.B to the thermal outline
 if( thermalOutline.Intersect( seg, intersections ) )
 {
 seg.B = intersections.front().p;
 
 VECTOR2I offset = ( seg.B - seg.A ).Perpendicular().Resize( spoke_half_w );
 SHAPE_LINE_CHAIN spoke;
 
 spoke.Append( seg.A + offset );
 spoke.Append( seg.A - offset );
 spoke.Append( seg.B - offset );
 spoke.Append( seg.B ); // test pt
 spoke.Append( seg.B + offset );
 
 spoke.SetClosed( true );
 aSpokesList.push_back( std::move( spoke ) );
 }
 }
 }
 }
 // If the spokes are at a cardinal angle then we can generate them from a bounding box
 // without trig.
 else if( ( pad->GetOrientation() + pad->GetThermalSpokeAngle() ).IsCardinal() )
 {
 BOX2I spokesBox = pad->GetBoundingBox();
 spokesBox.Inflate( thermalReliefGap + epsilon );
 
 // Spokes are from center of pad shape, not from hole.
 spokesBox.Offset( - pad->ShapePos() );
 
 buildSpokesFromOrigin( spokesBox );
 
 auto spokeIter = aSpokesList.rbegin();
 
 for( int ii = 0; ii < 4; ++ii, ++spokeIter )
 spokeIter->Move( pad->ShapePos() );
 }
 // Even if the spokes are rotated, we can fudge it for round and square pads by rotating
 // the bounding box to match the spokes.
 else if( pad->GetSizeX() == pad->GetSizeY() && pad->GetShape() != PAD_SHAPE::CUSTOM )
 {
 // Since the bounding-box needs to be correclty rotated we use a dummy pad to keep
 // from dirtying the real pad's cached shapes.
 PAD dummy_pad( *pad );
 dummy_pad.SetOrientation( pad->GetThermalSpokeAngle() );
 
 // Spokes are from center of pad shape, not from hole. So the dummy pad has no shape
 // offset and is at position 0,0
 dummy_pad.SetPosition( VECTOR2I( 0, 0 ) );
 dummy_pad.SetOffset( VECTOR2I( 0, 0 ) );
 
 BOX2I spokesBox = dummy_pad.GetBoundingBox();
 spokesBox.Inflate( thermalReliefGap + epsilon );
 
 buildSpokesFromOrigin( spokesBox );
 
 auto spokeIter = aSpokesList.rbegin();
 
 for( int ii = 0; ii < 4; ++ii, ++spokeIter )
 {
 spokeIter->Rotate( pad->GetOrientation() + pad->GetThermalSpokeAngle() );
 spokeIter->Move( pad->ShapePos() );
 }
 
 // Remove group membership from dummy item before deleting
 dummy_pad.SetParentGroup( nullptr );
 }
 // And lastly, even when we have to resort to trig, we can use it only in a post-process
 // after the rotated-bounding-box trick from above.
 else
 {
 // Since the bounding-box needs to be correclty rotated we use a dummy pad to keep
 // from dirtying the real pad's cached shapes.
 PAD dummy_pad( *pad );
 dummy_pad.SetOrientation( pad->GetThermalSpokeAngle() );
 
 // Spokes are from center of pad shape, not from hole. So the dummy pad has no shape
 // offset and is at position 0,0
 dummy_pad.SetPosition( VECTOR2I( 0, 0 ) );
 dummy_pad.SetOffset( VECTOR2I( 0, 0 ) );
 
 BOX2I spokesBox = dummy_pad.GetBoundingBox();
 
 // In this case make the box -big-; we're going to clip to the "real" bbox later.
 spokesBox.Inflate( thermalReliefGap + spokesBox.GetWidth() + spokesBox.GetHeight() );
 
 buildSpokesFromOrigin( spokesBox );
 
 BOX2I realBBox = pad->GetBoundingBox();
 realBBox.Inflate( thermalReliefGap + epsilon );
 
 auto spokeIter = aSpokesList.rbegin();
 
 for( int ii = 0; ii < 4; ++ii, ++spokeIter )
 {
 spokeIter->Rotate( pad->GetOrientation() + pad->GetThermalSpokeAngle() );
 spokeIter->Move( pad->ShapePos() );
 
 VECTOR2I origin_p = spokeIter->GetPoint( 0 );
 VECTOR2I origin_m = spokeIter->GetPoint( 1 );
 VECTOR2I origin = ( origin_p + origin_m ) / 2;
 VECTOR2I end_m = spokeIter->GetPoint( 2 );
 VECTOR2I end = spokeIter->GetPoint( 3 );
 VECTOR2I end_p = spokeIter->GetPoint( 4 );
 
 ClipLine( &realBBox, origin_p.x, origin_p.y, end_p.x, end_p.y );
 ClipLine( &realBBox, origin_m.x, origin_m.y, end_m.x, end_m.y );
 ClipLine( &realBBox, origin.x, origin.y, end.x, end.y );
 
 spokeIter->SetPoint( 2, end_m );
 spokeIter->SetPoint( 3, end );
 spokeIter->SetPoint( 4, end_p );
 }
 
 // Remove group membership from dummy item before deleting
 dummy_pad.SetParentGroup( nullptr );
 }
 }
 
 for( size_t ii = 0; ii < aSpokesList.size(); ++ii )
 aSpokesList[ii].GenerateBBoxCache();
}
 
 
bool ZONE_FILLER::addHatchFillTypeOnZone( const ZONE* aZone, PCB_LAYER_ID aLayer,
 PCB_LAYER_ID aDebugLayer, SHAPE_POLY_SET& aFillPolys )
{
 // Build grid:
 
 // obviously line thickness must be > zone min thickness.
 // It can happens if a board file was edited by hand by a python script
 // Use 1 micron margin to be *sure* there is no issue in Gerber files
 // (Gbr file unit = 1 or 10 nm) due to some truncation in coordinates or calculations
 // This margin also avoid problems due to rounding coordinates in next calculations
 // that can create incorrect polygons
 int thickness = std::max( aZone->GetHatchThickness(),
 aZone->GetMinThickness() + pcbIUScale.mmToIU( 0.001 ) );
 
 int linethickness = thickness - aZone->GetMinThickness();
 int gridsize = thickness + aZone->GetHatchGap();
 int maxError = m_board->GetDesignSettings().m_MaxError;
 
 SHAPE_POLY_SET filledPolys = aFillPolys.CloneDropTriangulation();
 // Use a area that contains the rotated bbox by orientation, and after rotate the result
 // by -orientation.
 if( !aZone->GetHatchOrientation().IsZero() )
 filledPolys.Rotate( - aZone->GetHatchOrientation() );
 
 BOX2I bbox = filledPolys.BBox( 0 );
 
 // Build hole shape
 // the hole size is aZone->GetHatchGap(), but because the outline thickness
 // is aZone->GetMinThickness(), the hole shape size must be larger
 SHAPE_LINE_CHAIN hole_base;
 int hole_size = aZone->GetHatchGap() + aZone->GetMinThickness();
 VECTOR2I corner( 0, 0 );;
 hole_base.Append( corner );
 corner.x += hole_size;
 hole_base.Append( corner );
 corner.y += hole_size;
 hole_base.Append( corner );
 corner.x = 0;
 hole_base.Append( corner );
 hole_base.SetClosed( true );
 
 // Calculate minimal area of a grid hole.
 // All holes smaller than a threshold will be removed
 double minimal_hole_area = hole_base.Area() * aZone->GetHatchHoleMinArea();
 
 // Now convert this hole to a smoothed shape:
 if( aZone->GetHatchSmoothingLevel() > 0 )
 {
 // the actual size of chamfer, or rounded corner radius is the half size
 // of the HatchFillTypeGap scaled by aZone->GetHatchSmoothingValue()
 // aZone->GetHatchSmoothingValue() = 1.0 is the max value for the chamfer or the
 // radius of corner (radius = half size of the hole)
 int smooth_value = KiROUND( aZone->GetHatchGap()
 * aZone->GetHatchSmoothingValue() / 2 );
 
 // Minimal optimization:
 // make smoothing only for reasonable smooth values, to avoid a lot of useless segments
 // and if the smooth value is small, use chamfer even if fillet is requested
 #define SMOOTH_MIN_VAL_MM 0.02
 #define SMOOTH_SMALL_VAL_MM 0.04
 
 if( smooth_value > pcbIUScale.mmToIU( SMOOTH_MIN_VAL_MM ) )
 {
 SHAPE_POLY_SET smooth_hole;
 smooth_hole.AddOutline( hole_base );
 int smooth_level = aZone->GetHatchSmoothingLevel();
 
 if( smooth_value < pcbIUScale.mmToIU( SMOOTH_SMALL_VAL_MM ) && smooth_level > 1 )
 smooth_level = 1;
 
 // Use a larger smooth_value to compensate the outline tickness
 // (chamfer is not visible is smooth value < outline thickess)
 smooth_value += aZone->GetMinThickness() / 2;
 
 // smooth_value cannot be bigger than the half size oh the hole:
 smooth_value = std::min( smooth_value, aZone->GetHatchGap() / 2 );
 
 // the error to approximate a circle by segments when smoothing corners by a arc
 maxError = std::max( maxError * 2, smooth_value / 20 );
 
 switch( smooth_level )
 {
 case 1:
 // Chamfer() uses the distance from a corner to create a end point
 // for the chamfer.
 hole_base = smooth_hole.Chamfer( smooth_value ).Outline( 0 );
 break;
 
 default:
 if( aZone->GetHatchSmoothingLevel() > 2 )
 maxError /= 2; // Force better smoothing
 
 hole_base = smooth_hole.Fillet( smooth_value, maxError ).Outline( 0 );
 break;
 
 case 0:
 break;
 };
 }
 }
 
 // Build holes
 SHAPE_POLY_SET holes;
 
 for( int xx = 0; ; xx++ )
 {
 int xpos = xx * gridsize;
 
 if( xpos > bbox.GetWidth() )
 break;
 
 for( int yy = 0; ; yy++ )
 {
 int ypos = yy * gridsize;
 
 if( ypos > bbox.GetHeight() )
 break;
 
 // Generate hole
 SHAPE_LINE_CHAIN hole( hole_base );
 hole.Move( VECTOR2I( xpos, ypos ) );
 holes.AddOutline( hole );
 }
 }
 
 holes.Move( bbox.GetPosition() );
 
 if( !aZone->GetHatchOrientation().IsZero() )
 holes.Rotate( aZone->GetHatchOrientation() );
 
 DUMP_POLYS_TO_COPPER_LAYER( holes, In10_Cu, wxT( "hatch-holes" ) );
 
 int outline_margin = aZone->GetMinThickness() * 1.1;
 
 // Using GetHatchThickness() can look more consistent than GetMinThickness().
 if( aZone->GetHatchBorderAlgorithm() && aZone->GetHatchThickness() > outline_margin )
 outline_margin = aZone->GetHatchThickness();
 
 // The fill has already been deflated to ensure GetMinThickness() so we just have to
 // account for anything beyond that.
 SHAPE_POLY_SET deflatedFilledPolys = aFillPolys.CloneDropTriangulation();
 deflatedFilledPolys.Deflate( outline_margin - aZone->GetMinThickness(),
 CORNER_STRATEGY::CHAMFER_ALL_CORNERS, maxError );
 holes.BooleanIntersection( deflatedFilledPolys, SHAPE_POLY_SET::PM_FAST );
 DUMP_POLYS_TO_COPPER_LAYER( holes, In11_Cu, wxT( "fill-clipped-hatch-holes" ) );
 
 SHAPE_POLY_SET deflatedOutline = aZone->Outline()->CloneDropTriangulation();
 deflatedOutline.Deflate( outline_margin, CORNER_STRATEGY::CHAMFER_ALL_CORNERS, maxError );
 holes.BooleanIntersection( deflatedOutline, SHAPE_POLY_SET::PM_FAST );
 DUMP_POLYS_TO_COPPER_LAYER( holes, In12_Cu, wxT( "outline-clipped-hatch-holes" ) );
 
 if( aZone->GetNetCode() != 0 )
 {
 // Vias and pads connected to the zone must not be allowed to become isolated inside
 // one of the holes. Effectively this means their copper outline needs to be expanded
 // to be at least as wide as the gap so that it is guaranteed to touch at least one
 // edge.
 BOX2I zone_boundingbox = aZone->GetBoundingBox();
 SHAPE_POLY_SET aprons;
 int min_apron_radius = ( aZone->GetHatchGap() * 10 ) / 19;
 
 for( PCB_TRACK* track : m_board->Tracks() )
 {
 if( track->Type() == PCB_VIA_T )
 {
 PCB_VIA* via = static_cast<PCB_VIA*>( track );
 
 if( via->GetNetCode() == aZone->GetNetCode()
 && via->IsOnLayer( aLayer )
 && via->GetBoundingBox().Intersects( zone_boundingbox ) )
 {
 int r = std::max( min_apron_radius,
 via->GetDrillValue() / 2 + outline_margin );
 
 TransformCircleToPolygon( aprons, via->GetPosition(), r, maxError,
 ERROR_OUTSIDE );
 }
 }
 }
 
 for( FOOTPRINT* footprint : m_board->Footprints() )
 {
 for( PAD* pad : footprint->Pads() )
 {
 if( pad->GetNetCode() == aZone->GetNetCode()
 && pad->IsOnLayer( aLayer )
 && pad->GetBoundingBox().Intersects( zone_boundingbox ) )
 {
 // What we want is to bulk up the pad shape so that the narrowest bit of
 // copper between the hole and the apron edge is at least outline_margin
 // wide (and that the apron itself meets min_apron_radius. But that would
 // take a lot of code and math, and the following approximation is close
 // enough.
 int pad_width = std::min( pad->GetSize().x, pad->GetSize().y );
 int slot_width = std::min( pad->GetDrillSize().x, pad->GetDrillSize().y );
 int min_annular_ring_width = ( pad_width - slot_width ) / 2;
 int clearance = std::max( min_apron_radius - pad_width / 2,
 outline_margin - min_annular_ring_width );
 
 clearance = std::max( 0, clearance - linethickness / 2 );
 pad->TransformShapeToPolygon( aprons, aLayer, clearance, maxError,
 ERROR_OUTSIDE );
 }
 }
 }
 
 holes.BooleanSubtract( aprons, SHAPE_POLY_SET::PM_FAST );
 }
 DUMP_POLYS_TO_COPPER_LAYER( holes, In13_Cu, wxT( "pad-via-clipped-hatch-holes" ) );
 
 // Now filter truncated holes to avoid small holes in pattern
 // It happens for holes near the zone outline
 for( int ii = 0; ii < holes.OutlineCount(); )
 {
 double area = holes.Outline( ii ).Area();
 
 if( area < minimal_hole_area ) // The current hole is too small: remove it
 holes.DeletePolygon( ii );
 else
 ++ii;
 }
 
 // create grid. Use SHAPE_POLY_SET::PM_STRICTLY_SIMPLE to
 // generate strictly simple polygons needed by Gerber files and Fracture()
 aFillPolys.BooleanSubtract( aFillPolys, holes, SHAPE_POLY_SET::PM_STRICTLY_SIMPLE );
 DUMP_POLYS_TO_COPPER_LAYER( aFillPolys, In14_Cu, wxT( "after-hatching" ) );
 
 return true;
}