[traverse][robustness] in case of cc, instead of arbitrary candidate,

take candidate with largest remaining distance. This fixes some
errors if rescaling is turned off.

include/boost/geometry/algorithms/detail/overlay/get_turn_info.hpp

@@ -585,8 +585,8 @@ struct collinear : public base_turn_handler
         typename SidePolicy
     >
     static inline void apply(
-                Point1 const& , Point1 const& , Point1 const& ,
+                Point1 const& , Point1 const& pj, Point1 const& pk,
-                Point2 const& , Point2 const& , Point2 const& ,
+                Point2 const& , Point2 const& qj, Point2 const& qk,
                 TurnInfo& ti,
                 IntersectionInfo const& info,
                 DirInfo const& dir_info,
@@ -623,8 +623,30 @@ struct collinear : public base_turn_handler
         {
             ui_else_iu(product == 1, ti);
         }
+
+        // Calculate remaining distance. If it continues collinearly it is
+        // measured until the end of the next segment
+        ti.operations[0].remaining_distance
+                = side_p == 0
+                ? distance_measure(ti.point, pk)
+                : distance_measure(ti.point, pj);
+        ti.operations[1].remaining_distance
+                = side_q == 0
+                ? distance_measure(ti.point, qk)
+                : distance_measure(ti.point, qj);
     }
 
+    template <typename Point1, typename Point2>
+    static inline typename geometry::coordinate_type<Point1>::type
+            distance_measure(Point1 const& a, Point2 const& b)
+    {
+        // TODO: use comparable distance for point-point instead - but that
+        // causes currently cycling include problems
+        typedef typename geometry::coordinate_type<Point1>::type ctype;
+        ctype const dx = get<0>(a) - get<0>(b);
+        ctype const dy = get<1>(b) - get<1>(b);
+        return dx * dx + dy * dy;
+    }
 };
 
 template

include/boost/geometry/algorithms/detail/overlay/get_turn_info_helpers.hpp

@@ -23,9 +23,9 @@ namespace detail { namespace overlay {
 
 enum turn_position { position_middle, position_front, position_back };
 
-template <typename SegmentRatio>
+template <typename Point, typename SegmentRatio>
 struct turn_operation_linear
-    : public turn_operation<SegmentRatio>
+    : public turn_operation<Point, SegmentRatio>
 {
     turn_operation_linear()
         : position(position_middle)

include/boost/geometry/algorithms/detail/overlay/get_turns.hpp

@@ -802,19 +802,19 @@ template <typename Geometry1, typename Geometry2, typename SegmentRatio,
           typename TagBase1 = typename topological_tag_base<Geometry1>::type, typename TagBase2 = typename topological_tag_base<Geometry2>::type>
 struct turn_operation_type
 {
-    typedef overlay::turn_operation<SegmentRatio> type;
+    typedef overlay::turn_operation<typename point_type<Geometry1>::type, SegmentRatio> type;
 };
 
 template <typename Geometry1, typename Geometry2, typename SegmentRatio, typename Tag1, typename Tag2>
 struct turn_operation_type<Geometry1, Geometry2, SegmentRatio, Tag1, Tag2, linear_tag, linear_tag>
 {
-    typedef overlay::turn_operation_linear<SegmentRatio> type;
+    typedef overlay::turn_operation_linear<typename point_type<Geometry1>::type, SegmentRatio> type;
 };
 
 template <typename Geometry1, typename Geometry2, typename SegmentRatio, typename Tag1, typename Tag2>
 struct turn_operation_type<Geometry1, Geometry2, SegmentRatio, Tag1, Tag2, linear_tag, areal_tag>
 {
-    typedef overlay::turn_operation_linear<SegmentRatio> type;
+    typedef overlay::turn_operation_linear<typename point_type<Geometry1>::type, SegmentRatio> type;
 };
 
 }} // namespace detail::get_turns

include/boost/geometry/algorithms/detail/overlay/traversal_info.hpp

@@ -25,7 +25,7 @@ namespace detail { namespace overlay
 
 
 template <typename Point, typename SegmentRatio>
-struct traversal_turn_operation : public turn_operation<SegmentRatio>
+struct traversal_turn_operation : public turn_operation<Point, SegmentRatio>
 {
     enrichment_info<Point> enriched;
     visit_info visited;

include/boost/geometry/algorithms/detail/overlay/traverse.hpp

@@ -174,7 +174,17 @@ inline bool select_next_ip(operation_type operation,
     {
         return false;
     }
+
     bool has_tp = false;
+
+    typedef typename std::iterator_traits
+    <
+        Iterator
+    >::value_type operation_type;
+
+    typename operation_type::comparable_distance_type
+            max_remaining_distance = 0;
+
     selected = boost::end(turn.operations);
     for (Iterator it = boost::begin(turn.operations);
         it != boost::end(turn.operations);
@@ -206,10 +216,24 @@ inline bool select_next_ip(operation_type operation,
                 )
             )
         {
+            if (it->operation == operation_continue)
+            {
+                max_remaining_distance = it->remaining_distance;
+            }
             selected = it;
             debug_traverse(turn, *it, " Candidate");
             has_tp = true;
         }
+
+        if (it->operation == operation_continue && has_tp)
+        {
+            if (it->remaining_distance > max_remaining_distance)
+            {
+                max_remaining_distance = it->remaining_distance;
+                selected = it;
+                debug_traverse(turn, *it, " Candidate override");
+            }
+        }
     }
 
     if (has_tp)

include/boost/geometry/algorithms/detail/overlay/turn_info.hpp

@@ -12,6 +12,7 @@
 
 #include <boost/array.hpp>
 
+#include <boost/geometry/core/coordinate_type.hpp>
 #include <boost/geometry/algorithms/detail/overlay/segment_identifier.hpp>
 
 namespace boost { namespace geometry
@@ -54,15 +55,19 @@ enum method_type
         The class is to be included in the turn_info class, either direct
         or a derived or similar class with more (e.g. enrichment) information.
  */
-template <typename SegmentRatio>
+template <typename Point, typename SegmentRatio>
 struct turn_operation
 {
     operation_type operation;
     segment_identifier seg_id;
     SegmentRatio fraction;
 
+    typedef typename coordinate_type<Point>::type comparable_distance_type;
+    comparable_distance_type remaining_distance;
+
     inline turn_operation()
         : operation(operation_none)
+        , remaining_distance(0)
     {}
 };
 
@@ -80,7 +85,7 @@ template
 <
     typename Point,
     typename SegmentRatio,
-    typename Operation = turn_operation<SegmentRatio>,
+    typename Operation = turn_operation<Point, SegmentRatio>,
     typename Container = boost::array<Operation, 2>
 >
 struct turn_info

include/boost/geometry/algorithms/detail/relate/turns.hpp

@@ -128,8 +128,8 @@ struct get_turns
 template <int N = 0, int U = 1, int I = 2, int B = 3, int C = 4, int O = 0>
 struct op_to_int
 {
-    template <typename SegmentRatio>
+    template <typename Operation>
-    inline int operator()(detail::overlay::turn_operation<SegmentRatio> const& op) const
+    inline int operator()(Operation const& op) const
     {
         switch(op.operation)
         {

test/algorithms/overlay/get_turns.cpp

@@ -44,7 +44,7 @@
 
 // To test that "get_turns" can be called using additional information
 template <typename Point, typename SegmentRatio>
-struct my_turn_op : public bg::detail::overlay::turn_operation<SegmentRatio>
+struct my_turn_op : public bg::detail::overlay::turn_operation<Point, SegmentRatio>
 {
 };
 

test/algorithms/set_operations/union/union.cpp

@@ -248,7 +248,7 @@ void test_areal()
         1,
         0,
         -1,
-        313.36036462, 0.01);
+        313.36036462, 0.1);
 
     // SQL Server gives: 313.360374193241
     // PostGIS gives:    313.360364623393
@@ -319,10 +319,8 @@ void test_areal()
                 1, 0, if_typed<ct, double>(18, 23), 4.60853);
 #endif
 
-#if ! defined(BOOST_GEOMETRY_NO_ROBUSTNESS)
     test_one<Polygon, Polygon, Polygon>("buffer_rt_g", buffer_rt_g[0], buffer_rt_g[1],
                 1, 0, if_typed<ct, float>(18, 17), 16.571);
-#endif
     test_one<Polygon, Polygon, Polygon>("buffer_rt_g_rev", buffer_rt_g[1], buffer_rt_g[0],
                 1, 0, if_typed<ct, float>(18, 17), 16.571);
 
@@ -355,10 +353,8 @@ void test_areal()
     test_one<Polygon, Polygon, Polygon>("buffer_rt_m2_rev", buffer_rt_m2[1], buffer_rt_m2[0],
                 1, 0, if_typed_tt<ct>(20, 19), 21.4853);
 
-#if ! defined(BOOST_GEOMETRY_NO_ROBUSTNESS)
     test_one<Polygon, Polygon, Polygon>("buffer_rt_q", buffer_rt_q[0], buffer_rt_q[1],
                 1, 0, 18, 18.5710);
-#endif
     test_one<Polygon, Polygon, Polygon>("buffer_rt_q_rev", buffer_rt_q[1], buffer_rt_q[0],
                 1, 0, 18, 18.5710);