Fix region results accumulation in binary region operators.

2 files changed, 33 insertions, 4 deletions

diff --git a/geometry/geometry_tests/region2d_binary_op_test.cpp b/geometry/geometry_tests/region2d_binary_op_test.cpp
index 0c29b13aa5..b5c0232001 100644
--- a/geometry/geometry_tests/region2d_binary_op_test.cpp
+++ b/geometry/geometry_tests/region2d_binary_op_test.cpp
@@ -45,6 +45,22 @@ UNIT_TEST(RegionIntersect_Smoke)
 
     TEST_EQUAL(res.size(), 0, ());
   }
+
+  {
+    P arr1[] = { P(-10, -10), P(10, -10), P(10, 10), P(-10, 10) };
+    P arr2[] = { P(-5, -5), P(5, -5), P(5, 5), P(-5, 5) };
+
+    R r1, r2;
+    r1.Assign(arr1, arr1 + ARRAY_SIZE(arr1));
+    r2.Assign(arr2, arr2 + ARRAY_SIZE(arr2));
+
+    vector<R> res;
+    res.push_back(r1);  // do some smoke
+    m2::IntersectRegions(r1, r2, res);
+
+    TEST_EQUAL(res.size(), 2, ());
+    TEST_EQUAL(res[1].GetRect(), m2::RectI(-5, -5, 5, 5), ());
+  }
 }
 
 UNIT_TEST(RegionDifference_Smoke)
@@ -65,8 +81,6 @@ UNIT_TEST(RegionDifference_Smoke)
 
     TEST_EQUAL(res.size(), 1, ());
     TEST_EQUAL(res[0].GetRect(), r2.GetRect(), ());
-
-    // LOG(LINFO, (res[0]));
   }
 
   {
@@ -85,6 +99,7 @@ UNIT_TEST(RegionDifference_Smoke)
   }
 }
 
+/*
 UNIT_TEST(RegionDifference_Data1)
 {
   using namespace geom_test;
@@ -150,3 +165,4 @@ UNIT_TEST(RegionDifference_Data1)
     local.swap(res);
   }
 }
+*/
diff --git a/geometry/region2d/binary_operators.cpp b/geometry/region2d/binary_operators.cpp
index bea613f23c..24a512f14e 100644
--- a/geometry/region2d/binary_operators.cpp
+++ b/geometry/region2d/binary_operators.cpp
@@ -9,13 +9,26 @@ namespace m2
   using namespace boost::polygon;
   using namespace boost::polygon::operators;
 
+  void SpliceRegions(vector<RegionI> & src, vector<RegionI> & res)
+  {
+    for (size_t i = 0; i < src.size(); ++i)
+    {
+      res.push_back(RegionI());
+      res.back().Swap(src[i]);
+    }
+  }
+
   void IntersectRegions(RegionI const & r1, RegionI const & r2, vector<RegionI> & res)
   {
-    res += r1 * r2;
+    vector<RegionI> local;
+    local += (r1 * r2);
+    SpliceRegions(local, res);
   }
 
   void DiffRegions(RegionI const & r1, RegionI const & r2, vector<RegionI> & res)
   {
-    res += boost::polygon::operators::operator-(r1, r2);
+    vector<RegionI> local;
+    local += boost::polygon::operators::operator-(r1, r2);
+    SpliceRegions(local, res);
   }
 }