From b22a3c0530e8ecfe064b60243cebdcb9dcc4d431 Mon Sep 17 00:00:00 2001
From: Adam Wulkiewicz <adam.wulkiewicz@gmail.com>
Date: Fri, 21 Aug 2015 19:41:01 +0200
Subject: [PATCH] [sections] Enlarge section bounding Boxes WRT epsilon.

This allows the algorithms using sections to check spatial predicates
using raw operators < (e.g. in Box/Box disjoint). There is no need to
use less performant calls to math::smaller.

Replace math::smaller usage in section functions preceeding() and
exceeding() and therefore revert the change done recently.
---
 .../detail/sections/section_functions.hpp     | 10 ++++-----
 .../detail/sections/sectionalize.hpp          | 21 +++++++++++--------
 2 files changed, 17 insertions(+), 14 deletions(-)

diff --git a/include/boost/geometry/algorithms/detail/sections/section_functions.hpp b/include/boost/geometry/algorithms/detail/sections/section_functions.hpp
index 26980f154..7bc5c0804 100644
--- a/include/boost/geometry/algorithms/detail/sections/section_functions.hpp
+++ b/include/boost/geometry/algorithms/detail/sections/section_functions.hpp
@@ -18,7 +18,7 @@
 #include <boost/geometry/core/access.hpp>
 #include <boost/geometry/algorithms/detail/recalculate.hpp>
 #include <boost/geometry/policies/robustness/robust_point_type.hpp>
-#include <boost/geometry/util/math.hpp>
+
 
 namespace boost { namespace geometry
 {
@@ -40,8 +40,8 @@ static inline bool preceding(int dir, Point const& point,
 {
     typename geometry::robust_point_type<Point, RobustPolicy>::type robust_point;
     geometry::recalculate(robust_point, point, robust_policy);
-    return (dir == 1  && math::smaller(get<Dimension>(robust_point), get<min_corner, Dimension>(robust_box)))
-        || (dir == -1 && math::larger(get<Dimension>(robust_point), get<max_corner, Dimension>(robust_box)));
+    return (dir == 1  && get<Dimension>(robust_point) < get<min_corner, Dimension>(robust_box))
+        || (dir == -1 && get<Dimension>(robust_point) > get<max_corner, Dimension>(robust_box));
 }
 
 template
@@ -57,8 +57,8 @@ static inline bool exceeding(int dir, Point const& point,
 {
     typename geometry::robust_point_type<Point, RobustPolicy>::type robust_point;
     geometry::recalculate(robust_point, point, robust_policy);
-    return (dir == 1  && math::larger(get<Dimension>(robust_point), get<max_corner, Dimension>(robust_box)))
-        || (dir == -1 && math::smaller(get<Dimension>(robust_point), get<min_corner, Dimension>(robust_box)));
+    return (dir == 1  && get<Dimension>(robust_point) > get<max_corner, Dimension>(robust_box))
+        || (dir == -1 && get<Dimension>(robust_point) < get<min_corner, Dimension>(robust_box));
 }
 
 
diff --git a/include/boost/geometry/algorithms/detail/sections/sectionalize.hpp b/include/boost/geometry/algorithms/detail/sections/sectionalize.hpp
index 1ced39435..6443965e9 100644
--- a/include/boost/geometry/algorithms/detail/sections/sectionalize.hpp
+++ b/include/boost/geometry/algorithms/detail/sections/sectionalize.hpp
@@ -52,6 +52,8 @@
 #include <boost/geometry/views/reversible_view.hpp>
 #include <boost/geometry/geometries/segment.hpp>
 
+#include <boost/geometry/algorithms/detail/expand_by_epsilon.hpp>
+
 namespace boost { namespace geometry
 {
 
@@ -599,19 +601,18 @@ inline void enlarge_sections(Sections& sections)
     // Reason: turns might, rarely, be missed otherwise (case: "buffer_mp1")
     // Drawback: not really, range is now completely inside the section. Section is a tiny bit too large,
     // which might cause (a small number) of more comparisons
-    // TODO: make dimension-agnostic
+    
+    // NOTE: above is old comment to the not used code expanding the Boxes by relaxed_epsilon(10)
+    
+    // Enlarge sections by scaled epsilon, this should be consistent with math::equals().
+    // Points and Segments are equal-compared WRT machine epsilon, but Boxes aren't
+    // Enlarging Boxes ensures that they correspond to the bound objects,
+    // Segments in this case, since Sections are collections of Segments.
     for (typename boost::range_iterator<Sections>::type it = boost::begin(sections);
         it != boost::end(sections);
         ++it)
     {
-        typedef typename boost::range_value<Sections>::type section_type;
-        typedef typename section_type::box_type box_type;
-        typedef typename geometry::coordinate_type<box_type>::type coordinate_type;
-        coordinate_type const reps = math::relaxed_epsilon(10.0);
-        geometry::set<0, 0>(it->bounding_box, geometry::get<0, 0>(it->bounding_box) - reps);
-        geometry::set<0, 1>(it->bounding_box, geometry::get<0, 1>(it->bounding_box) - reps);
-        geometry::set<1, 0>(it->bounding_box, geometry::get<1, 0>(it->bounding_box) + reps);
-        geometry::set<1, 1>(it->bounding_box, geometry::get<1, 1>(it->bounding_box) + reps);
+        detail::expand_by_epsilon(it->bounding_box);
     }
 }
 
@@ -802,6 +803,8 @@ inline void sectionalize(Geometry const& geometry,
             Reverse,
             DimensionVector
         >::apply(geometry, robust_policy, sections, ring_id, max_count);
+
+    detail::sectionalize::enlarge_sections(sections);
 }