Bug #24563: MBROverlaps does not seem to function propertly.

Fix is to rewrite the MBR::overlaps() function, to compute the dimension of both
arguments, and the dimension of the intersection; test that all three dimensions are the
same (e.g., all are Polygons).

Add tests for all MBR* functions for various combinations of shapes, lines and points.


mysql-test/include/gis_generic.inc:
  Add tests & checks for bug #24563 and bug #24588 - some GIS functions missing in
  5.1; many GIS functions not tested; Overlaps() function was incorrect when MBR shifted
  only along one axis; Overlaps() needs to take dimension of shape into account.
mysql-test/r/archive_gis.result:
  Update test results.
mysql-test/r/bdb_gis.result:
  Update test results.
mysql-test/r/gis.result:
  Update test results.
mysql-test/r/innodb_gis.result:
  Update test results.
mysql-test/r/ndb_gis.result:
  Update test results.
mysql-test/t/gis.test:
  Add tests & checks for bug #24563 and bug #24588 - some GIS functions missing in
  5.1; many GIS functions not tested; Overlaps() function was incorrect when MBR shifted
  only along one axis; Overlaps() needs to take dimension of shape into account.
sql/spatial.h:
  Add MBR::dimension() (map MBR to integral dimension: point -> 0, line -> 1,
  polygon -> 2, invalid -> -1)
  
  Fix MBR::overlaps() to handle MBRs which are shifted on one dimension only, and to
  take MBR dimension into account.  Also, test both within() and contains() predicates (so
  that overlaps(a, b) == overlaps(b, a)).

1 files changed, 37 insertions, 6 deletions

diff --git a/sql/spatial.h b/sql/spatial.h
index 86232fcd524..837ae153310 100644
--- a/sql/spatial.h
+++ b/sql/spatial.h
@@ -144,15 +144,46 @@ struct MBR
     return (xmin<x) && (xmax>x) && (ymin<y) && (ymax>y);
   }
 
+  /**
+    The dimension maps to an integer as:
+    - Polygon -> 2
+    - Horizontal or vertical line -> 1
+    - Point -> 0
+    - Invalid MBR -> -1
+  */
+  int dimension() const
+  {
+    int d= 0;
+
+    if (xmin > xmax)
+      return -1;
+    else if (xmin < xmax)
+      d++;
+
+    if (ymin > ymax)
+      return -1;
+    else if (ymin < ymax)
+      d++;
+
+    return d;
+  }
+
   int overlaps(const MBR *mbr)
   {
-    int lb= mbr->inner_point(xmin, ymin);
-    int rb= mbr->inner_point(xmax, ymin);
-    int rt= mbr->inner_point(xmax, ymax);
-    int lt= mbr->inner_point(xmin, ymax);
+    /*
+      overlaps() requires that some point inside *this is also inside
+      *mbr, and that both geometries and their intersection are of the
+      same dimension.
+    */
+    int d = dimension();
+
+    if (d != mbr->dimension() || d <= 0 || contains(mbr) || within(mbr))
+      return 0;
+
+    MBR intersection(max(xmin, mbr->xmin), max(ymin, mbr->ymin),
+                     min(xmax, mbr->xmax), min(ymax, mbr->ymax));
 
-    int a = lb+rb+rt+lt;
-    return (a>0) && (a<4) && (!within(mbr));
+    return (d == intersection.dimension());
   }
 };