From 7a5aa1835b53f0195df9e339d6864a408dbff81c Mon Sep 17 00:00:00 2001
From: Max Lyon <max.lyon@autodesk.com>
Date: Wed, 25 May 2022 13:55:52 +0200
Subject: [PATCH] use calc_face_normal if no normal property is available

---
 src/OpenMesh/Core/Mesh/PolyMeshT_impl.hh | 8 ++++----
 1 file changed, 4 insertions(+), 4 deletions(-)

diff --git a/src/OpenMesh/Core/Mesh/PolyMeshT_impl.hh b/src/OpenMesh/Core/Mesh/PolyMeshT_impl.hh
index c98f2bed..96a00cd1 100644
--- a/src/OpenMesh/Core/Mesh/PolyMeshT_impl.hh
+++ b/src/OpenMesh/Core/Mesh/PolyMeshT_impl.hh
@@ -401,8 +401,8 @@ calc_halfedge_normal(HalfedgeHandle _heh, const double _feature_angle) const
     }
 
     Normal n(0,0,0);
-    for(unsigned int i=0; i<fhs.size(); ++i)
-      n += Kernel::normal(fhs[i]);
+    for (unsigned int i = 0; i < fhs.size(); ++i)
+      n += Kernel::has_face_normals() ? Kernel::normal(fhs[i]) : calc_face_normal(fhs[i]);
 
     return normalize(n);
   }
@@ -444,8 +444,8 @@ is_estimated_feature_edge(HalfedgeHandle _heh, const double _feature_angle) cons
   FaceHandle fh0 = Kernel::face_handle(_heh);
   FaceHandle fh1 = Kernel::face_handle(Kernel::opposite_halfedge_handle(_heh));
 
-  Normal fn0 = Kernel::normal(fh0);
-  Normal fn1 = Kernel::normal(fh1);
+  Normal fn0 = Kernel::has_face_normals() ? Kernel::normal(fh0) : calc_face_normal(fh0);
+  Normal fn1 = Kernel::has_face_normals() ? Kernel::normal(fh1) : calc_face_normal(fh1);
 
   // dihedral angle above angle threshold
   return ( dot(fn0,fn1) < cos(_feature_angle) );