[postgis-tickets] r17804 - Make ST_Simplify(TRIANGLE) collapse if requested

[Raul]

Author: algunenano
Date: 2019-09-05 10:10:57 -0700 (Thu, 05 Sep 2019)
New Revision: 17804

Modified:
   trunk/NEWS
   trunk/liblwgeom/lwgeom.c
   trunk/regress/core/simplify.sql
   trunk/regress/core/simplify_expected
Log:
Make ST_Simplify(TRIANGLE) collapse if requested

References #4496
Closes https://github.com/postgis/postgis/pull/474



Modified: trunk/NEWS
===================================================================
--- trunk/NEWS	2019-09-05 15:27:36 UTC (rev 17803)
+++ trunk/NEWS	2019-09-05 17:10:57 UTC (rev 17804)
@@ -9,6 +9,7 @@
   - #4494, Fix ST_Simplify output having an outdated bbox (Raúl Marín)
   - #4493, Fix ST_RemoveRepeatedPoints output having an outdated bbox (Raúl Marín)
   - #4495, Fix ST_SnapToGrid output having an outdated bbox (Raúl Marín)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 3.0.0alpha4
 2019/08/10

Modified: trunk/liblwgeom/lwgeom.c
===================================================================
--- trunk/liblwgeom/lwgeom.c	2019-09-05 15:27:36 UTC (rev 17803)
+++ trunk/liblwgeom/lwgeom.c	2019-09-05 17:10:57 UTC (rev 17804)
@@ -1704,8 +1704,19 @@
 	{
 		/* No-op! Cannot simplify points or triangles */
 		case POINTTYPE:
+			return;
 		case TRIANGLETYPE:
-			return;
+		{
+			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);

Modified: trunk/regress/core/simplify.sql
===================================================================
--- trunk/regress/core/simplify.sql	2019-09-05 15:27:36 UTC (rev 17803)
+++ trunk/regress/core/simplify.sql	2019-09-05 17:10:57 UTC (rev 17804)
@@ -21,4 +21,8 @@
 (
     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

Modified: trunk/regress/core/simplify_expected
===================================================================
--- trunk/regress/core/simplify_expected	2019-09-05 15:27:36 UTC (rev 17803)
+++ trunk/regress/core/simplify_expected	2019-09-05 17:10:57 UTC (rev 17804)
@@ -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|