From 61dfe46ab97befe51779db672c80dedb5139499b Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?S=C3=A9bastien=20Loriot?= <sebastien.loriot@cgal.org>
Date: Thu, 28 Nov 2013 17:19:52 +0100
Subject: [PATCH] fix regression in the Triangle_3-Triangle_3 intersection
 computation

this has been introduced when rewriting the code for the removal
of Object
---
 .../CGAL/Triangle_3_Triangle_3_intersection.h | 20 ++++++++++++-------
 .../triangle_3_triangle_3_intersection.cpp    |  6 ++++++
 2 files changed, 19 insertions(+), 7 deletions(-)

diff --git a/Intersections_3/include/CGAL/Triangle_3_Triangle_3_intersection.h b/Intersections_3/include/CGAL/Triangle_3_Triangle_3_intersection.h
index 1f15c6c0cc9..162813a490f 100644
--- a/Intersections_3/include/CGAL/Triangle_3_Triangle_3_intersection.h
+++ b/Intersections_3/include/CGAL/Triangle_3_Triangle_3_intersection.h
@@ -132,18 +132,24 @@ struct Triangle_Line_visitor {
   ::result_type result_type;
 
   result_type
-  operator()(const typename K::Point_3& p, const typename K::Segment_3&) const {
-    return intersection_return<typename K::Intersect_3, typename K::Triangle_3, typename K::Triangle_3>(p);
+  operator()(const typename K::Point_3& p, const typename K::Segment_3& s) const {
+    if ( s.has_on(p) )
+      return intersection_return<typename K::Intersect_3, typename K::Triangle_3, typename K::Triangle_3>(p);
+    else
+      return result_type();
   }
 
   result_type
-  operator()(const typename K::Segment_3&, const typename K::Point_3& p) const {
-    return intersection_return<typename K::Intersect_3, typename K::Triangle_3, typename K::Triangle_3>(p);
+  operator()(const typename K::Segment_3& s, const typename K::Point_3& p) const {
+    return operator()(p,s);
   }
 
   result_type
-  operator()(const typename K::Point_3& p1, const typename K::Point_3&) const {
-    return intersection_return<typename K::Intersect_3, typename K::Triangle_3, typename K::Triangle_3>(p1);
+  operator()(const typename K::Point_3& p1, const typename K::Point_3& p2) const {
+    if (p1==p2)
+      return intersection_return<typename K::Intersect_3, typename K::Triangle_3, typename K::Triangle_3>(p1);
+    else
+      return result_type();
   }
 
   result_type
@@ -158,7 +164,7 @@ struct Triangle_Line_visitor {
         return intersection_return<typename K::Intersect_3, typename K::Triangle_3, typename K::Triangle_3>(*p);
     }
 
-    return intersection_return<typename K::Intersect_3, typename K::Triangle_3, typename K::Triangle_3>();
+    return result_type();
   }
 };
   
diff --git a/Intersections_3/test/Intersections_3/triangle_3_triangle_3_intersection.cpp b/Intersections_3/test/Intersections_3/triangle_3_triangle_3_intersection.cpp
index 9282a403e12..a809689492f 100644
--- a/Intersections_3/test/Intersections_3/triangle_3_triangle_3_intersection.cpp
+++ b/Intersections_3/test/Intersections_3/triangle_3_triangle_3_intersection.cpp
@@ -273,6 +273,12 @@ void test_non_coplanar_triangles()
   assert(obj.empty());
   obj=CGAL::intersection(t2,t1);
   assert(obj.empty());  
+  t1=Triangle( Point( 0, 0, 0 ), Point( 0, 1, 1 ), Point( 0, 1, 0 ) );
+  t2=Triangle( Point( -1, -1, 0 ),Point( 0, -1, 0 ),Point( -1, 0, 0 ) );
+  obj=CGAL::intersection(t1,t2);
+  assert(obj.empty());
+  obj=CGAL::intersection(t2,t1);
+  assert(obj.empty());
 }
 
 int main()