From 51dc7b02b3dacaed54f689add0c6c70421b3c7e6 Mon Sep 17 00:00:00 2001
From: isn <isn@opencascade.com>
Date: Tue, 15 Nov 2016 17:31:55 +0300
Subject: [PATCH] refs #1043

---
 src/HYDROGUI/HYDROGUI_Polyline.cxx | 6 ++++--
 1 file changed, 4 insertions(+), 2 deletions(-)

diff --git a/src/HYDROGUI/HYDROGUI_Polyline.cxx b/src/HYDROGUI/HYDROGUI_Polyline.cxx
index 532c6071..7225e2e6 100644
--- a/src/HYDROGUI/HYDROGUI_Polyline.cxx
+++ b/src/HYDROGUI/HYDROGUI_Polyline.cxx
@@ -154,7 +154,8 @@ void HYDROGUI_Polyline::Compute(const Handle(PrsMgr_PresentationManager3d)& aPre
     
     gp_Pnt aPnt1 = C->Value (aMaxRatioStep);
     gp_Vec aDir;
-    if (!UseD1) {
+    if (!UseD1) 
+    {
       GCPnts_AbscissaPoint aAbsPoint(aAdC, -aArrLen, aMaxRatioStep);
       double aParam = aAbsPoint.Parameter();      
       gp_Pnt aPnt2 = C->Value (aParam);
@@ -162,7 +163,8 @@ void HYDROGUI_Polyline::Compute(const Handle(PrsMgr_PresentationManager3d)& aPre
       D.Subtract (aPnt2.XYZ());
       aDir = D;
     }
-    else
+
+    if (UseD1 || aDir.IsEqual (gp_Vec(0,0,0), Precision::Confusion(), Precision::Angular()))
       C->D1(aMaxRatioStep, aPnt1, aDir);
   
     if ( anEdge.Orientation() == TopAbs_REVERSED )
-- 
2.39.2