From c8fd295f190901b8983d4517e3801a5ce3a6777d Mon Sep 17 00:00:00 2001
From: Efi Fogel <efif@post.tau.ac.il>
Date: Wed, 28 Aug 2002 18:06:13 +0000
Subject: [PATCH] work around bug in Homogeneous kernel

---
 .../include/CGAL/Pm_segment_traits_2.h        | 40 +++++++++++++++++++
 1 file changed, 40 insertions(+)

diff --git a/Packages/Planar_map/include/CGAL/Pm_segment_traits_2.h b/Packages/Planar_map/include/CGAL/Pm_segment_traits_2.h
index 7fa211eb9ec..8c6d2aadb50 100644
--- a/Packages/Planar_map/include/CGAL/Pm_segment_traits_2.h
+++ b/Packages/Planar_map/include/CGAL/Pm_segment_traits_2.h
@@ -142,7 +142,11 @@ public:
     
     // <cv2> and <cv1> meet at a point with the same x-coordinate as q
     // compare their derivatives
+#ifndef NBUG
+    return compare_value(curve_derivative(cv2), curve_derivative(cv1));
+#else
     return compare_slope_2_object()(cv2, cv1);
+#endif
   }
 
   /*! curve_compare_at_x_right() compares the y value of two curves in an
@@ -173,7 +177,25 @@ public:
     
     // <cv1> and <cv2> meet at a point with the same x-coordinate as q
     // compare their derivatives
+#if 1
+#ifndef NBUG
+    return compare_value(curve_derivative(cv1), curve_derivative(cv2));
+#else
     return compare_slope_2_object()(cv1, cv2);
+#endif
+#else
+    Comparison_result resGood =
+        compare_value(curve_derivative(cv1), curve_derivative(cv2));
+    Comparison_result resBad = compare_slope_2_object()(cv1, cv2);
+    if (resGood != resBad) {
+        std::cout << "good: " << resGood << std::endl;
+        std::cout << "bad: " << resBad << std::endl;
+        std::cout << "cv1: " << cv1 << std::endl;
+        std::cout << "cv2: " << cv2 << std::endl;
+        std::cout << "  p: " << q << std::endl;
+    }
+    return resGood;
+#endif
   }
     
   /*! Return the curve-point status of the input objects
@@ -233,6 +255,24 @@ public:
    */
   bool point_is_right(const Point_2 & p1, const  Point_2 & p2) const
   { return less_x_2_object()(p2, p1); }
+
+#ifndef NBUG
+private:
+  typename Kernel::FT curve_derivative(const X_curve_2 &cv) const
+  {
+    CGAL_assertion(!curve_is_vertical(cv));
+    return ( (cv.target()).y() - cv.source().y()) / 
+      (cv.target().x() - cv.source().x());
+  }
+    
+  Comparison_result compare_value(const typename Kernel::FT & v1, 
+                                  const typename Kernel::FT & v2) const
+  {
+    typename Kernel::FT d = v1 - v2;
+    typename Kernel::FT z(0);
+    return ((d == z) ? EQUAL : ((z < d) ? LARGER : SMALLER));
+  }
+#endif
 };
 
 CGAL_END_NAMESPACE