router: disable 'limit corner count' optimization for via dragging

It seems to be completely preventing optimization instead of preventing over-optimization in case the head is a dragged via.
To be investigated in more details in V7.

Fixes: https://gitlab.com/kicad/code/kicad/-/issues/8665

pcbnew/router/pns_dragger.cpp

@@ -650,6 +650,9 @@ bool DRAGGER::dragShove( const VECTOR2I& aP )
     {
         VIA_HANDLE newVia;
 
+        // corner count limiter intended to avoid excessive optimization produces mediocre results for via shoving.
+        // this is a hack that disables it, before I figure out a more reliable solution
+        m_shove->DisablePostShoveOptimizations( OPTIMIZER::LIMIT_CORNER_COUNT );
         SHOVE::SHOVE_STATUS st = m_shove->ShoveDraggingVia( m_draggedVia, aP, newVia );
 
         if( st == SHOVE::SH_OK || st == SHOVE::SH_HEAD_MODIFIED )

pcbnew/router/pns_optimizer.cpp

@@ -271,6 +271,7 @@ bool CORNER_COUNT_LIMIT_CONSTRAINT::Check( int aVertex1, int aVertex2, const LIN
 {
     LINE newPath( *aOriginLine, aCurrentPath );
     newPath.Line().Replace( aVertex1, aVertex2, aReplacement );
+    newPath.Line().Simplify();
     int cc = newPath.CountCorners( m_angleMask );
 
     if( cc >= m_minCorners && cc <= m_maxCorners )

pcbnew/router/pns_shove.cpp

@@ -159,6 +159,7 @@ void SHOVE::sanityCheck( LINE* aOld, LINE* aNew )
 SHOVE::SHOVE( NODE* aWorld, ROUTER* aRouter ) :
     ALGO_BASE( aRouter )
 {
+    m_optFlagDisableMask = 0;
     m_forceClearance = -1;
     m_root = aWorld;
     m_currentNode = aWorld;
@@ -1759,7 +1760,8 @@ void SHOVE::runOptimizer( NODE* aNode )
     if( Settings().SmartPads() )
         optFlags |= OPTIMIZER::SMART_PADS;
 
-    optimizer.SetEffortLevel( optFlags );
+
+    optimizer.SetEffortLevel( optFlags & ~m_optFlagDisableMask );
     optimizer.SetCollisionMask( ITEM::ANY_T );
 
     for( int pass = 0; pass < n_passes; pass++ )
@@ -1873,5 +1875,11 @@ void SHOVE::UnlockSpringbackNode( NODE* aNode )
     }
 }
 
+
+void SHOVE::DisablePostShoveOptimizations( int aMask )
+{
+    m_optFlagDisableMask = aMask;
+}
+
 }
 

pcbnew/router/pns_shove.h

@@ -89,6 +89,7 @@ public:
     void UnlockSpringbackNode( NODE* aNode );
     bool RewindSpringbackTo( NODE* aNode );
     bool RewindToLastLockedNode();
+    void DisablePostShoveOptimizations( int aMask );
 
 private:
     typedef std::vector<SHAPE_LINE_CHAIN> HULL_SET;
@@ -180,6 +181,8 @@ private:
     int                         m_iter;
     int m_forceClearance;
     bool m_multiLineMode;
+
+    int m_optFlagDisableMask;
 };
 
 }