From 6b1e578377eb24e94a2e4b16721e2a540da9f190 Mon Sep 17 00:00:00 2001
From: Andreas Fabri <Andreas.Fabri@geometryfactory.com>
Date: Mon, 27 Sep 2010 10:53:45 +0000
Subject: [PATCH] Take care of collinear points when computing a facet normal

---
 Polyhedron/demo/Polyhedron/include/CGAL/compute_normal.h | 4 +++-
 1 file changed, 3 insertions(+), 1 deletion(-)

diff --git a/Polyhedron/demo/Polyhedron/include/CGAL/compute_normal.h b/Polyhedron/demo/Polyhedron/include/CGAL/compute_normal.h
index 3437332ab75..61cbf051d3c 100644
--- a/Polyhedron/demo/Polyhedron/include/CGAL/compute_normal.h
+++ b/Polyhedron/demo/Polyhedron/include/CGAL/compute_normal.h
@@ -16,7 +16,9 @@ typename Kernel::Vector_3 compute_facet_normal(const Facet& f)
     const Point& curr = he->vertex()->point();
     const Point& next = he->next()->vertex()->point();
     Vector n = CGAL::cross_product(next-curr,prev-curr);
-    normal = normal + (n / std::sqrt(n*n));
+    if((n*n) > 0.000000001){
+      normal = normal + (n / std::sqrt(n*n));
+    }
   }
   return normal / std::sqrt(normal * normal);
 }