From a165f002806e1e2137caf3eb17e5892f9cef4288 Mon Sep 17 00:00:00 2001
From: razmyslovich <razmyslovich@volumegraphics.com>
Date: Mon, 12 Sep 2016 11:17:48 +0200
Subject: [PATCH] 0027863: Geom_BSplineSurface::SetVKnot(const
 Standard_Integer, const Standard_Real) has no effect

Fix Geom_BSplineSurface::SetVKnot function to have the same behavior as SetUKnot.
---
 src/Geom/Geom_BSplineSurface.cxx | 7 +++++--
 1 file changed, 5 insertions(+), 2 deletions(-)

diff --git a/src/Geom/Geom_BSplineSurface.cxx b/src/Geom/Geom_BSplineSurface.cxx
index a328ab5a8d..2d7153accf 100644
--- a/src/Geom/Geom_BSplineSurface.cxx
+++ b/src/Geom/Geom_BSplineSurface.cxx
@@ -1099,8 +1099,11 @@ void Geom_BSplineSurface::SetVKnot
     } 
   }
   
-  maxderivinvok = 0;
-  UpdateVKnots();
+  if (K != vknots->Value (NewIndex)) {
+    vknots->SetValue (NewIndex, K);
+    maxderivinvok = 0;
+    UpdateVKnots();
+  }
 }
 
 //=======================================================================