From abe7c4404d0784d949ade97fe6aef90b6970676e Mon Sep 17 00:00:00 2001
From: Markus Lampert <markus@bibi.ca>
Date: Mon, 28 Nov 2016 15:10:25 -0800
Subject: [PATCH] Enhance makeHelix to also support helixes that spiral
 downwards.

---
 src/Mod/Part/App/TopoShape.cpp | 7 +++++--
 1 file changed, 5 insertions(+), 2 deletions(-)

diff --git a/src/Mod/Part/App/TopoShape.cpp b/src/Mod/Part/App/TopoShape.cpp
index b67187db38..d8d0531751 100644
--- a/src/Mod/Part/App/TopoShape.cpp
+++ b/src/Mod/Part/App/TopoShape.cpp
@@ -1659,12 +1659,15 @@ TopoDS_Shape TopoShape::makeHelix(Standard_Real pitch, Standard_Real height,
                                   Standard_Boolean leftHanded,
                                   Standard_Boolean newStyle) const
 {
-    if (pitch < Precision::Confusion())
+    if (fabs(pitch) < Precision::Confusion())
         Standard_Failure::Raise("Pitch of helix too small");
 
-    if (height < Precision::Confusion())
+    if (fabs(height) < Precision::Confusion())
         Standard_Failure::Raise("Height of helix too small");
 
+    if ((height > 0 && pitch < 0) || (height < 0 && pitch > 0))
+        Standard_Failure::Raise("Pitch and height of helix not compatible");
+
     gp_Ax2 cylAx2(gp_Pnt(0.0,0.0,0.0) , gp::DZ());
     Handle_Geom_Surface surf;
     if (angle < Precision::Confusion()) {