From 6554279e9a254b22da2610eee81a7a07fe73746a Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?S=C3=A9bastien=20Loriot?= <sebastien.loriot@cgal.org>
Date: Tue, 12 May 2015 10:21:53 +0200
Subject: [PATCH] fix the test for the dimension of the affine hull of the dual
 points

---
 .../dual/halfspace_intersection_3.h           | 25 ++++++++-----------
 .../test_halfspace_intersections.cpp          |  3 ++-
 2 files changed, 12 insertions(+), 16 deletions(-)

diff --git a/Convex_hull_3/include/CGAL/Convex_hull_3/dual/halfspace_intersection_3.h b/Convex_hull_3/include/CGAL/Convex_hull_3/dual/halfspace_intersection_3.h
index 1f9061d44c2..15cf91f451a 100644
--- a/Convex_hull_3/include/CGAL/Convex_hull_3/dual/halfspace_intersection_3.h
+++ b/Convex_hull_3/include/CGAL/Convex_hull_3/dual/halfspace_intersection_3.h
@@ -211,31 +211,26 @@ namespace CGAL
                 if (size < 4)
                     return false;
 
-                // Collinear
+                // Look for two non-parallel planes
                 PlaneIterator plane1_it = planes.begin();
-                PlaneIterator plane2_it = planes.begin();
-                ++plane2_it;
+                PlaneIterator plane2_it = cpp11::next(planes.begin());
 
-                PlaneIterator plane3_it = planes.end();
-                --plane3_it;
                 while (plane2_it != planes.end() &&
                        collinear_plane(*plane1_it, *plane2_it)) {
                     ++plane2_it;
                 }
 
-                if (plane2_it == planes.end()) {
-                    return false;
-                }
+                if (plane2_it == planes.end()) return false;
 
-                // Coplanar
-                while (plane2_it != planes.end() &&
+                PlaneIterator plane3_it = cpp11::next(plane2_it);
+
+                // Look for a triple of planes intersecting in a point
+                while (plane3_it != planes.end() &&
                        coplanar_plane(*plane1_it, *plane2_it, *plane3_it)) {
-                    plane2_it++;
+                    ++plane3_it;
                 }
 
-                if (plane2_it == planes.end()) {
-                    return false;
-                }
+                if (plane3_it == planes.end()) return false;
 
                 return true;
             }
@@ -249,7 +244,7 @@ namespace CGAL
     void halfspace_intersection_3 (PlaneIterator begin, PlaneIterator end,
                                    Polyhedron &P,
                                    boost::optional<typename Polyhedron::Vertex::Point_3> const& origin = boost::none) {
-        // Checks whether the intersection if a polyhedron
+        // Checks whether the intersection is a polyhedron
         CGAL_assertion_msg(Convex_hull_3::internal::is_intersection_dim_3(begin, end), "halfspace_intersection_3: intersection not a polyhedron");
 
         // Types
diff --git a/Convex_hull_3/test/Convex_hull_3/test_halfspace_intersections.cpp b/Convex_hull_3/test/Convex_hull_3/test_halfspace_intersections.cpp
index 4a851b6fe29..5c818d20e26 100644
--- a/Convex_hull_3/test/Convex_hull_3/test_halfspace_intersections.cpp
+++ b/Convex_hull_3/test/Convex_hull_3/test_halfspace_intersections.cpp
@@ -16,12 +16,13 @@ int main (void) {
 
   // generates supporting planes of the facets of a cube
   std::vector<Plane> planes;
+
   planes.push_back( Plane( 1, 0, 0,-1) ); // x= 1
-  planes.push_back( Plane(-1, 0, 0,-1) ); // x=-1
   planes.push_back( Plane( 0, 1, 0,-1) ); // y= 1
   planes.push_back( Plane( 0,-1, 0,-1) ); // y=-1
   planes.push_back( Plane( 0, 0, 1,-1) ); // z= 1
   planes.push_back( Plane( 0, 0,-1,-1) ); // z=-1
+  planes.push_back( Plane(-1, 0, 0,-1) ); // x=-1
 
   // define polyhedron to hold the intersection
   Polyhedron_3 P1, P2, P3, P4, P5;