Fix numerical issue for segments sharing a common point

boostorg · Feb 13, 2024 · 68a225d · 68a225d
1 parent b9737c5
commit 68a225d
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Showing 8 changed files with 63 additions and 18 deletions.
diff --git a/include/boost/geometry/policies/relate/direction.hpp b/include/boost/geometry/policies/relate/direction.hpp
@@ -163,6 +163,14 @@ struct segments_direction
             ;
     }
 
+    template <typename SegmentIntersectionInfo, typename Point>
+    static inline return_type segments_share_common_point(side_info const& sides,
+                                                          SegmentIntersectionInfo const& ,
+                                                          Point const&)
+    {
+        return segments_crosses(sides, sides, sides, sides);
+    }
+
     template <typename Ratio>
     static inline int arrival_value(Ratio const& r_from, Ratio const& r_to)
     {

diff --git a/include/boost/geometry/policies/relate/intersection_points.hpp b/include/boost/geometry/policies/relate/intersection_points.hpp
@@ -18,6 +18,7 @@
 #include <algorithm>
 #include <string>
 
+#include <boost/geometry/algorithms/assign.hpp>
 #include <boost/geometry/algorithms/detail/assign_indexed_point.hpp>
 #include <boost/geometry/core/access.hpp>
 #include <boost/geometry/core/assert.hpp>
@@ -61,6 +62,21 @@ struct segments_intersection_points
         return result;
     }
 
+    template<typename SegmentIntersectionInfo, typename Point>
+    static inline return_type
+    segments_share_common_point(side_info const&, SegmentIntersectionInfo const& sinfo,
+                                Point const& p)
+    {
+        return_type result;
+        result.count = 1;
+        boost::geometry::assign(result.intersections[0], p);
+
+        // Temporary - this should go later
+        result.fractions[0].assign(sinfo);
+
+        return result;
+    }
+
     template <typename Segment1, typename Segment2, typename Ratio>
     static inline return_type segments_collinear(
         Segment1 const& a, Segment2 const& b, bool /*opposite*/,

diff --git a/include/boost/geometry/policies/relate/intersection_policy.hpp b/include/boost/geometry/policies/relate/intersection_policy.hpp
@@ -67,6 +67,19 @@ struct segments_intersection_policy
             );
     }
 
+    template <typename SegmentIntersectionInfo, typename Point>
+    static inline return_type
+    segments_share_common_point(side_info const& sides,
+                                SegmentIntersectionInfo const& sinfo,
+                                Point const& p)
+    {
+        return return_type
+            (
+                pts_policy::segments_share_common_point(sides, sinfo, p),
+                dir_policy::segments_share_common_point(sides, sinfo, p)
+            );
+    }
+
     template <typename Segment1, typename Segment2, typename Ratio>
     static inline return_type segments_collinear(
                                         Segment1 const& segment1,

diff --git a/include/boost/geometry/policies/relate/intersection_ratios.hpp b/include/boost/geometry/policies/relate/intersection_ratios.hpp
@@ -55,6 +55,16 @@ struct segments_intersection_ratios
         return result;
     }
 
+    template<typename SegmentIntersectionInfo, typename Point>
+    static inline return_type
+    segments_share_common_point(side_info const&, SegmentIntersectionInfo const& sinfo,
+                                Point const& p)
+    {
+        return_type result;
+        result.assign(sinfo);
+        return result;
+    }
+
     template <typename Segment1, typename Segment2, typename Ratio>
     static inline return_type segments_collinear(
         Segment1 const& , Segment2 const& ,

diff --git a/include/boost/geometry/strategies/cartesian/intersection.hpp b/include/boost/geometry/strategies/cartesian/intersection.hpp
@@ -459,6 +459,7 @@ struct cartesian_segments
 
         bool collinear = sides.collinear();
 
+        //TODO: remove this when rescaling is removed
         // Calculate the differences again
         // (for rescaled version, this is different from dx_p etc)
         coordinate_type const dx_p = get<0>(p2) - get<0>(p1);
@@ -533,6 +534,16 @@ struct cartesian_segments
             }
         }
 
+        if (equals_point_point(p1, q1) || equals_point_point(p1, q2))
+        {
+            return Policy::segments_share_common_point(sides, sinfo, p1);
+        }
+
+        if (equals_point_point(p2, q1) || equals_point_point(p2, q2))
+        {
+            return Policy::segments_share_common_point(sides, sinfo, p2);
+        }
+
         return Policy::segments_crosses(sides, sinfo, p, q);
     }
 

diff --git a/test/algorithms/is_simple.cpp b/test/algorithms/is_simple.cpp
@@ -263,14 +263,8 @@ BOOST_AUTO_TEST_CASE( test_geometry_with_NaN_coordinates )
     std::cout << "************************************" << std::endl;
 #endif
 
-    linestring_type ls1, ls2;
-    bg::read_wkt("LINESTRING(1 1,1.115235e+308 1.738137e+308)", ls1);
-    bg::read_wkt("LINESTRING(-1 1,1.115235e+308 1.738137e+308)", ls2);
-
-    // the intersection of the two linestrings is a new linestring
-    // (multilinestring with a single element) that has NaN coordinates
     multi_linestring_type mls;
-    bg::intersection(ls1, ls2, mls);
+    bg::read_wkt("MULTILINESTRING((nan nan))", mls);
 
     test_simple(mls, true, false);
 }

diff --git a/test/algorithms/is_valid.cpp b/test/algorithms/is_valid.cpp
@@ -1433,14 +1433,8 @@ BOOST_AUTO_TEST_CASE( test_with_NaN_coordinates )
     std::cout << "************************************" << std::endl;
 #endif
 
-    linestring_type ls1, ls2;
-    bg::read_wkt("LINESTRING(1 1,1.115235e+308 1.738137e+308)", ls1);
-    bg::read_wkt("LINESTRING(-1 1,1.115235e+308 1.738137e+308)", ls2);
-
-    // the intersection of the two linestrings is a new linestring
-    // (multilinestring with a single element) that has NaN coordinates
     multi_linestring_type mls;
-    bg::intersection(ls1, ls2, mls);
+    bg::read_wkt("MULTILINESTRING((nan nan))", mls);
 
     typedef validity_tester_linear<true> tester_allow_spikes;
     typedef validity_tester_linear<false> tester_disallow_spikes;

diff --git a/test/algorithms/set_operations/intersection/intersection_linear_linear.cpp b/test/algorithms/set_operations/intersection/intersection_linear_linear.cpp
@@ -8,7 +8,6 @@
 // Licensed under the Boost Software License version 1.0.
 // http://www.boost.org/users/license.html
 
-
 #include <iostream>
 
 #ifndef BOOST_TEST_MODULE
@@ -1300,7 +1299,7 @@ BOOST_AUTO_TEST_CASE( test_intersection_ml_ml_degenerate )
     // NOTE: if get_turn_info uses policy_verify_all then the result is different
 
   #if BOOST_GEOMETRY_INTERSECTION_DO_NOT_INCLUDE_ISOLATED_POINTS
-         from_wkt<ML>("MULTILINESTRING((-0.7654 8.88178e-16,-0.7654 0,5 3))"),
+         from_wkt<ML>("MULTILINESTRING((-0.7654 0,5 3))"),
   #else
          from_wkt<ML>("MULTILINESTRING((-0.756651 3.30964),(1.60494 6),\
                       (2.51371 6),(3.26673 6),(4 6),(8.18862 3.07616),\
@@ -1337,7 +1336,7 @@ BOOST_AUTO_TEST_CASE( test_intersection_ml_ml_degenerate )
                       (8.5655 2.85228),(5.26567 4.81254),(4 3.8),\
                       (1.4995 3.27036),(0.591231 3.43401),\
                       (-0.706503 3.66784),\
-                      (-0.7654 8.88178e-16,-0.7654 0,5 3))"),
+                      (-0.7654 0,5 3))"),
          from_wkt<ML>("MULTILINESTRING((1.87562 6.68515),(1.60494 6),\
                       (1.18124 4.9275),(1.00439 4.47984),(0.91526 4.25422),\
                       (0.729883 3.78498),(0.614728 3.49349),\
@@ -1368,7 +1367,7 @@ BOOST_AUTO_TEST_CASE( test_intersection_ml_ml_degenerate )
                       (9.98265 0.00543606),(9.09826 -100.515944),\
                       (7.08745 -329.0674155),(5.06428 -559.024344),\
                       (3.23365 -767.0972558),(3.16036 -775.427199),\
-                      (-0.7654 8.88178e-16,-0.7654 0,5 3))"),
+                      (-0.7654 0,5 3))"),
   #endif // isolated
           "mlmli21",
           1e-4