From 0c05fc6e80ce6e59686e15628f8cac02e6ba73d5 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Mael=20Rouxel-Labb=C3=A9?=
 <mael.rouxel.labbe@geometryfactory.com>
Date: Tue, 4 Feb 2020 15:56:55 +0100
Subject: [PATCH] More fixes for normal computations of meshes with degenerate
 faces

---
 .../include/CGAL/Polygon_mesh_processing/compute_normal.h  | 7 ++++---
 1 file changed, 4 insertions(+), 3 deletions(-)

diff --git a/Polygon_mesh_processing/include/CGAL/Polygon_mesh_processing/compute_normal.h b/Polygon_mesh_processing/include/CGAL/Polygon_mesh_processing/compute_normal.h
index 0c254332e78..3600992a7e0 100644
--- a/Polygon_mesh_processing/include/CGAL/Polygon_mesh_processing/compute_normal.h
+++ b/Polygon_mesh_processing/include/CGAL/Polygon_mesh_processing/compute_normal.h
@@ -265,6 +265,8 @@ bool does_enclose_other_normals(const std::size_t i, const std::size_t j, const
       continue;
 
     const Vector_ref nl = get(face_normals, incident_faces[l]);
+    if(nl == CGAL::NULL_VECTOR)
+      continue;
 
     // this is a bound on how much the scalar product between (v1,v2) and (v1, v3) can change
     // when the angle changes theta_bound := 0.01°
@@ -432,9 +434,8 @@ compute_most_visible_normal_3_points(const std::vector<typename boost::graph_tra
         const Vector_ref nj = get(face_normals, incident_faces[j]);
         const Vector_ref nk = get(face_normals, incident_faces[k]);
 
-        CGAL_warning(ni != CGAL::NULL_VECTOR);
-        CGAL_warning(nj != CGAL::NULL_VECTOR);
-        CGAL_warning(nk != CGAL::NULL_VECTOR);
+        if(ni == CGAL::NULL_VECTOR || nj == CGAL::NULL_VECTOR || nk == CGAL::NULL_VECTOR)
+          continue;
 
         Vector_3 nb = compute_normals_bisector(ni, nj, nk, traits);
         if(traits.equal_3_object()(nb, CGAL::NULL_VECTOR))