From 1d9ca181a25a78fe06cdd834c478a34b65c87908 Mon Sep 17 00:00:00 2001
From: Jon Evans <jon@craftyjon.com>
Date: Mon, 12 Apr 2021 22:34:13 -0400
Subject: [PATCH] PNS: Use existing seg direction if both DP segs are parallel

---
 pcbnew/router/pns_diff_pair.cpp | 13 +++++++++++++
 1 file changed, 13 insertions(+)

diff --git a/pcbnew/router/pns_diff_pair.cpp b/pcbnew/router/pns_diff_pair.cpp
index 9d11b391f2..a6f5d2df46 100644
--- a/pcbnew/router/pns_diff_pair.cpp
+++ b/pcbnew/router/pns_diff_pair.cpp
@@ -125,6 +125,19 @@ void DP_PRIMITIVE_PAIR::CursorOrientation( const VECTOR2I& aCursorPos, VECTOR2I&
     {
         aP = m_primP->Anchor( 1 );
         aN = m_primN->Anchor( 1 );
+
+        // If both segments are parallel, use that as the direction.  Otherwise, fall back on the
+        // direction perpendicular to the anchor points.
+        const SEG& segP = static_cast<SEGMENT*>( m_primP )->Seg();
+        const SEG& segN = static_cast<SEGMENT*>( m_primN )->Seg();
+
+        if( ( segP.B != segP.A ) && ( segN.B != segN.A ) && segP.ApproxParallel( segN ) )
+        {
+            aMidpoint  = ( aP + aN ) / 2;
+            aDirection = segP.B - segP.A;
+            aDirection = aDirection.Resize( ( aP - aN ).EuclideanNorm() );
+            return;
+        }
     }
     else
     {