From: Raúl Marín Rodríguez <rmrodriguez@carto.com>
Date: Thu, 5 Sep 2019 17:11:29 +0000 (+0000)
Subject: Make ST_Simplify(TRIANGLE) collapse if requested
X-Git-Url: https://granicus.if.org/sourcecode?a=commitdiff_plain;h=ce423115b8de876edb2cd2add914937a01f91a88;p=postgis

Make ST_Simplify(TRIANGLE) collapse if requested

Closes #4496


git-svn-id: http://svn.osgeo.org/postgis/branches/2.5@17805 b70326c6-7e19-0410-871a-916f4a2858ee
---

diff --git a/NEWS b/NEWS
index 8e363dbea..3966cc1d5 100644
--- a/NEWS
+++ b/NEWS
@@ -10,6 +10,7 @@ XXXX/XX/XX
   - #4494, Fix ST_Simplify output having an outdated bbox (Raúl Marín)
   - #4493, Fix ST_RemoveRepeatedPoints output having an outdated bbox (Raúl Marín)
   - #4495, Fix ST_SnapToGrid output having an outdated bbox (Raúl Marín)
+  - #4496, Make ST_Simplify(TRIANGLE) collapse if requested (Raúl Marín)
 
 PostGIS 2.5.3
 2019/08/11
diff --git a/liblwgeom/lwgeom.c b/liblwgeom/lwgeom.c
index e152ff540..12873ed3e 100644
--- a/liblwgeom/lwgeom.c
+++ b/liblwgeom/lwgeom.c
@@ -1753,8 +1753,19 @@ lwgeom_simplify_in_place(LWGEOM *geom, double epsilon, int preserve_collapsed)
 	{
 		/* No-op! Cannot simplify points or triangles */
 		case POINTTYPE:
-		case TRIANGLETYPE:
 			return;
+		case TRIANGLETYPE:
+		{
+			if (preserve_collapsed)
+				return;
+			LWTRIANGLE *t = lwgeom_as_lwtriangle(geom);
+			POINTARRAY *pa = t->points;
+			ptarray_simplify_in_place(pa, epsilon, 0);
+			if (pa->npoints < 3)
+			{
+				pa->npoints = 0;
+			}
+		}
 		case LINETYPE:
 		{
 			LWLINE *g = (LWLINE*)(geom);
diff --git a/regress/simplify.sql b/regress/simplify.sql
index a8a343b36..d5c2b01c2 100644
--- a/regress/simplify.sql
+++ b/regress/simplify.sql
@@ -21,4 +21,8 @@ WITH geom AS
 (
     SELECT ST_Simplify('POLYGON((0 0, 10 0, 10 10, 10.6 10, 10.5 10.5, 10 10, 0 10, 0 0))', 1) as g
 )
-Select '15', ST_AsText(g) as geometry, postgis_getbbox(g) AS box from geom;
\ No newline at end of file
+Select '15', ST_AsText(g) as geometry, postgis_getbbox(g) AS box from geom;
+
+-- Triangle should collapse if requested
+SELECT '16', ST_AsText(ST_Simplify('TRIANGLE ((0 0, 0 9, 9 0, 0 0))', 10, true));
+SELECT '17', ST_AsText(ST_Simplify('TRIANGLE ((0 0, 0 9, 9 0, 0 0))', 10, false));
\ No newline at end of file
diff --git a/regress/simplify_expected b/regress/simplify_expected
index c2920ecd0..63bcb8c7e 100644
--- a/regress/simplify_expected
+++ b/regress/simplify_expected
@@ -13,3 +13,5 @@
 13|
 14|POLYGON((0 0,10 0,10 10,0 0))
 15|POLYGON((0 0,10 0,10.5 10.5,0 10,0 0))|BOX(0 0,10.5 10.5)
+16|TRIANGLE((0 0,0 9,9 0,0 0))
+17|