Rewrite EDIT_TOOL::FilletTracks to only carry out the operation when one item is connected to the anchors

Fixes https://gitlab.com/kicad/code/kicad/-/issues/6103

pcbnew/tools/edit_tool.cpp

@@ -46,7 +46,9 @@
 #include <tools/pad_tool.h>
 #include <pad_naming.h>
 #include <view/view_controls.h>
+#include <connectivity/connectivity_algo.h>
 #include <connectivity/connectivity_data.h>
+#include <connectivity/connectivity_items.h>
 #include <confirm.h>
 #include <bitmaps.h>
 #include <cassert>
@@ -747,30 +749,80 @@ int EDIT_TOOL::FilletTracks( const TOOL_EVENT& aEvent )
         return 0;
     }
 
+
+    struct FILLET_OP
+    {
+        TRACK* t1;
+        TRACK* t2;
+        //If true, start point of track is modified after ARC is added, otherwise the end point:
+        bool   t1Start = true; 
+        bool   t2Start = true;
+    };
+
+    std::vector<FILLET_OP> filletOperations;
+    KICAD_T                track_types[] = { PCB_PAD_T, PCB_VIA_T, PCB_TRACE_T, PCB_ARC_T, EOT };
     bool                   operationPerformedOnAtLeastOne = false;
     bool                   didOneAttemptFail              = false;
-
-    std::vector<BOARD_ITEM*> itemsToAddToSelection;
+    std::set<TRACK*>       processedTracks;
 
     for( auto it = selection.begin(); it != selection.end(); it++ )
     {
-        TRACK* track1 = dyn_cast<TRACK*>( *it );
+        TRACK* track = dyn_cast<TRACK*>( *it );
 
-        if( !track1 || track1->Type() != PCB_TRACE_T || track1->IsLocked()
-                || track1->GetLength() == 0 )
+        if( !track || track->Type() != PCB_TRACE_T || track->IsLocked()
+                || track->GetLength() == 0 )
         {
             continue;
         }        
 
-        for( auto it2 = it + 1; it2 != selection.end(); it2++ )
+        auto processFilletOp = 
+            [&]( bool aStartPoint ) 
             {
-            TRACK* track2 = dyn_cast<TRACK*>( *it2 );
+                wxPoint anchor = ( aStartPoint ) ? track->GetStart() : track->GetEnd();
 
-            if( !track2 || track2->Type() != PCB_TRACE_T || track2->IsLocked()
-                    || track2->GetLength() == 0 )
+                std::vector<BOARD_CONNECTED_ITEM*> itemsOnAnchor =
+                    board()->GetConnectivity()->GetConnectedItemsAtAnchor( track, VECTOR2I( anchor ),
+                                                                   track_types );
+
+                if( itemsOnAnchor.size() > 0 && selection.Contains( itemsOnAnchor.at( 0 ) )
+                        && itemsOnAnchor.at( 0 )->Type() == PCB_TRACE_T )
                 {
-                continue;
+                    TRACK* trackOther = dyn_cast<TRACK*>( itemsOnAnchor.at( 0 ) );
+
+                    // Make sure we don't fillet the same pair of tracks twice
+                    if( processedTracks.find( trackOther ) == processedTracks.end() )
+                    {
+                        if( itemsOnAnchor.size() == 1 )
+                        {
+                            FILLET_OP filletOp;
+                            filletOp.t1      = track;
+                            filletOp.t2      = trackOther;
+                            filletOp.t1Start = aStartPoint;
+                            filletOp.t2Start = track->IsPointOnEnds( filletOp.t2->GetStart() );
+                            filletOperations.push_back( filletOp );
                         }
+                        else
+                        {
+                            // User requested to fillet these two tracks but not possible as there are other
+                            // elements connected at that point
+                            didOneAttemptFail = true;
+                        }
+                    }
+                }
+            };
+        
+        processFilletOp( true ); // on the start point of track
+        processFilletOp( false ); // on the end point of track
+        
+        processedTracks.insert( track );
+    }
+
+    std::vector<BOARD_ITEM*> itemsToAddToSelection;
+
+    for( FILLET_OP filletOp : filletOperations )
+    {
+        TRACK* track1 = filletOp.t1;
+        TRACK* track2 = filletOp.t2;
 
         bool trackOnStart = track1->IsPointOnEnds( track2->GetStart() );
         bool trackOnEnd   = track1->IsPointOnEnds( track2->GetEnd() );
@@ -790,12 +842,12 @@ int EDIT_TOOL::FilletTracks( const TOOL_EVENT& aEvent )
 
             wxPoint t1newPoint, t2newPoint;
 
-                auto setIfPointOnSeg =
-                        []( wxPoint& aPointToSet, SEG aSegment, VECTOR2I aVecToTest )
+            auto setIfPointOnSeg = []( wxPoint& aPointToSet, SEG aSegment, VECTOR2I aVecToTest ) 
                                    {
-                            // Find out if we are within the segment
-                            if( ( aSegment.NearestPoint( aVecToTest ) - aVecToTest ).EuclideanNorm()
-                                  < SHAPE_ARC::MIN_PRECISION_IU )
+                                       VECTOR2I segToVec = aSegment.NearestPoint( aVecToTest ) - aVecToTest;
+
+                                       // Find out if we are on the segment (minimum precision)
+                                       if( segToVec.EuclideanNorm() < SHAPE_ARC::MIN_PRECISION_IU )
                                        {
                                            aPointToSet.x = aVecToTest.x;
                                            aPointToSet.y = aVecToTest.y;
@@ -830,31 +882,19 @@ int EDIT_TOOL::FilletTracks( const TOOL_EVENT& aEvent )
             m_commit->Modify( track1 );
             m_commit->Modify( track2 );
 
-                if( track1->GetStart() == track2->GetStart() )
-                {
+            if( filletOp.t1Start )
                 track1->SetStart( t1newPoint );
-                    track2->SetStart( t2newPoint );
-                }
-                else if( track1->GetStart() == track2->GetEnd() )
-                {
-                    track1->SetStart( t1newPoint );
-                    track2->SetEnd( t2newPoint );
-                }
-                else if( track1->GetEnd() == track2->GetEnd() )
-                {
-                    track1->SetEnd( t1newPoint );
-                    track2->SetEnd( t2newPoint );
-                }
             else
-                {
                 track1->SetEnd( t1newPoint );
+            
+            if( filletOp.t2Start )
                 track2->SetStart( t2newPoint );
-                }
+            else
+                track2->SetEnd( t2newPoint );
 
             operationPerformedOnAtLeastOne = true;
         }
     }
-    }
 
     m_commit->Push( _( "Fillet Tracks" ) );