From: Paul Ramsey <pramsey@cleverelephant.ca>
Date: Tue, 7 Jul 2015 21:02:03 +0000 (+0000)
Subject: From dbaston <https://github.com/postgis/postgis/pull/40> resolves outstanding TODO... 
X-Git-Tag: 2.2.0rc1~258
X-Git-Url: https://granicus.if.org/sourcecode?a=commitdiff_plain;h=b8946f6cff80cf6b5c1d0ade3ee0951fe06a32ea;p=postgis

From dbaston <https://github.com/postgis/postgis/pull/40> resolves outstanding TODO list item


git-svn-id: http://svn.osgeo.org/postgis/trunk@13788 b70326c6-7e19-0410-871a-916f4a2858ee
---

diff --git a/liblwgeom/cunit/cu_libgeom.c b/liblwgeom/cunit/cu_libgeom.c
index 99c5d13f1..6fb3187d1 100644
--- a/liblwgeom/cunit/cu_libgeom.c
+++ b/liblwgeom/cunit/cu_libgeom.c
@@ -1038,6 +1038,40 @@ static void test_lwgeom_scale(void)
 	lwgeom_free(geom);
 }
 
+void test_gbox_same_2d(void);
+void test_gbox_same_2d(void)
+{
+	LWGEOM* g1 = lwgeom_from_wkt("LINESTRING(0 0, 1 1)", LW_PARSER_CHECK_NONE);
+    LWGEOM* g2 = lwgeom_from_wkt("LINESTRING(0 0, 0 1, 1 1)", LW_PARSER_CHECK_NONE);
+    LWGEOM* g3 = lwgeom_from_wkt("LINESTRING(0 0, 1 1.000000000001)", LW_PARSER_CHECK_NONE);
+
+    lwgeom_add_bbox(g1);
+    lwgeom_add_bbox(g2);
+    lwgeom_add_bbox(g3);
+
+    CU_ASSERT_TRUE(gbox_same_2d(g1->bbox, g2->bbox));
+    CU_ASSERT_FALSE(gbox_same_2d(g1->bbox, g3->bbox));
+    
+    /* Serializing a GBOX with precise coordinates renders the boxes not strictly equal,
+     * but still equal according to gbox_same_2d_float.
+     */
+    GSERIALIZED* s3 = gserialized_from_lwgeom(g3, LW_FALSE, NULL);
+    GBOX s3box;
+    gserialized_read_gbox_p(s3, &s3box);
+
+    CU_ASSERT_FALSE(gbox_same_2d(g3->bbox, &s3box));
+    CU_ASSERT_TRUE(gbox_same_2d_float(g3->bbox, &s3box));
+
+    /* The serialized box equals itself by either the exact or closest-float compares */
+    CU_ASSERT_TRUE(gbox_same_2d(&s3box, &s3box));
+    CU_ASSERT_TRUE(gbox_same_2d_float(&s3box, &s3box));
+
+    lwgeom_free(g1);
+    lwgeom_free(g2);
+    lwgeom_free(g3);
+    lwfree(s3);
+}
+
 /*
 ** Used by test harness to register the tests in this file.
 */
@@ -1067,4 +1101,5 @@ void libgeom_suite_setup(void)
 	PG_ADD_TEST(suite, test_lwgeom_as_curve);
 	PG_ADD_TEST(suite, test_lwgeom_scale);
 	PG_ADD_TEST(suite, test_gserialized_is_empty);
+    PG_ADD_TEST(suite, test_gbox_same_2d);
 }
diff --git a/liblwgeom/g_box.c b/liblwgeom/g_box.c
index aac64f786..3269ac3b5 100644
--- a/liblwgeom/g_box.c
+++ b/liblwgeom/g_box.c
@@ -143,8 +143,7 @@ int gbox_same(const GBOX *g1, const GBOX *g2)
 	if (FLAGS_GET_ZM(g1->flags) != FLAGS_GET_ZM(g2->flags))
 		return LW_FALSE;
 
-	if ( g1->xmin != g2->xmin || g1->ymin != g2->ymin ||
-	     g1->xmax != g2->xmax || g1->ymax != g2->ymax ) return LW_FALSE;
+	if (!gbox_same_2d(g1, g2)) return LW_FALSE;
 
 	if (FLAGS_GET_Z(g1->flags) && (g1->zmin != g2->zmin || g1->zmax != g2->zmax))
 		return LW_FALSE;
@@ -154,6 +153,24 @@ int gbox_same(const GBOX *g1, const GBOX *g2)
 	return LW_TRUE;
 }
 
+int gbox_same_2d(const GBOX *g1, const GBOX *g2)
+{
+    if (g1->xmin == g2->xmin && g1->ymin == g2->ymin &&
+        g1->xmax == g2->xmax && g1->ymax == g2->ymax)
+		return LW_TRUE;
+	return LW_FALSE;
+}
+
+int gbox_same_2d_float(const GBOX *g1, const GBOX *g2)
+{
+  if  ((g1->xmax == g2->xmax || next_float_up(g1->xmax)   == next_float_up(g2->xmax))   &&
+       (g1->ymax == g2->ymax || next_float_up(g1->ymax)   == next_float_up(g2->ymax))   &&
+       (g1->xmin == g2->xmin || next_float_down(g1->xmin) == next_float_down(g1->xmin)) &&
+       (g1->ymin == g2->ymin || next_float_down(g2->ymin) == next_float_down(g2->ymin)))
+      return LW_TRUE;
+  return LW_FALSE;
+}
+
 int gbox_is_valid(const GBOX *gbox)
 {
 	/* X */
diff --git a/liblwgeom/liblwgeom.h.in b/liblwgeom/liblwgeom.h.in
index a3a249baf..9677f706c 100644
--- a/liblwgeom/liblwgeom.h.in
+++ b/liblwgeom/liblwgeom.h.in
@@ -1796,6 +1796,17 @@ extern size_t gbox_serialized_size(uint8_t flags);
 */
 extern int gbox_same(const GBOX *g1, const GBOX *g2);
 
+/**
+* Check if 2 given GBOX are the same in x and y
+*/
+extern int gbox_same_2d(const GBOX *g1, const GBOX *g2);
+
+/**
+* Check if two given GBOX are the same in x and y, or would round to the same
+* GBOX in x and if serialized in GSERIALIZED
+*/
+extern int gbox_same_2d_float(const GBOX *g1, const GBOX *g2);
+
 /**
  * Round given GBOX to float boundaries
  *
diff --git a/postgis/lwgeom_geos.c b/postgis/lwgeom_geos.c
index f26394c72..0a5aed515 100644
--- a/postgis/lwgeom_geos.c
+++ b/postgis/lwgeom_geos.c
@@ -3085,15 +3085,13 @@ Datum ST_Equals(PG_FUNCTION_ARGS)
 		PG_RETURN_BOOL(TRUE);
 
 	/*
-	 * short-circuit: Loose test, if geom2 bounding box does not overlap
-	 * geom1 bounding box we can prematurely return FALSE.
-	 *
-	 * TODO: use gbox_same_2d instead (not available at time of writing)
+	 * short-circuit: If geom1 and geom2 do not have the same bounding box
+	 * we can return FALSE.
 	 */
-	if ( gserialized_get_gbox_p(geom1, &box1) &&
-	        gserialized_get_gbox_p(geom2, &box2) )
+	if ( gserialized_read_gbox_p(geom1, &box1) &&
+	        gserialized_read_gbox_p(geom2, &box2) )
 	{
-		if ( gbox_overlaps_2d(&box1, &box2) == LW_FALSE )
+		if ( gbox_same_2d_float(&box1, &box2) == LW_FALSE )
 		{
 			PG_RETURN_BOOL(FALSE);
 		}