From 56c59353bbd7f8535efc707822ac074d7b64e052 Mon Sep 17 00:00:00 2001
From: Joachim Schoeberl <joachim.schoeberl@tuwien.ac.at>
Date: Wed, 11 Aug 2021 21:54:45 +0200
Subject: [PATCH] surface normal

---
 libsrc/occ/python_occ_shapes.cpp | 8 ++++++++
 1 file changed, 8 insertions(+)

diff --git a/libsrc/occ/python_occ_shapes.cpp b/libsrc/occ/python_occ_shapes.cpp
index 5377876e..abd08a04 100644
--- a/libsrc/occ/python_occ_shapes.cpp
+++ b/libsrc/occ/python_occ_shapes.cpp
@@ -48,6 +48,7 @@
 #include <GCE2d_MakeSegment.hxx>
 #include <GCE2d_MakeCircle.hxx>
 #include <ShapeUpgrade_UnifySameDomain.hxx>
+#include <GeomLProp_SLProps.hxx>
 
 #if OCC_VERSION_MAJOR>=7 && OCC_VERSION_MINOR>=4
 #define OCC_HAVE_DUMP_JSON
@@ -617,6 +618,13 @@ DLL_HEADER void ExportNgOCCShapes(py::module &m)
         surf->D1 (u,v,p,du,dv);
         return tuple(p,du,dv);
       })
+    
+    .def("Normal", [] (const Handle(Geom_Surface) & surf, double u, double v) {
+        GeomLProp_SLProps lprop(surf,u,v,1,1e-8);
+        if (lprop.IsNormalDefined())
+          return lprop.Normal();
+        throw Exception("normal not defined");
+      })
     ;