From dee57bfb5f0c121d0a41e4d7f3d1416bc74a94d5 Mon Sep 17 00:00:00 2001
From: Sandro Santilli <strk@keybit.net>
Date: Thu, 13 Dec 2012 09:34:48 +0000
Subject: [PATCH] Revert "Return NULL when simplifying a line results in a line
 with < 2 vertices"

The correct behavior is still being discussed here:
http://trac.osgeo.org/postgis/ticket/1987
Better reduce the noise...

git-svn-id: http://svn.osgeo.org/postgis/trunk@10822 b70326c6-7e19-0410-871a-916f4a2858ee
---
 NEWS                     |  1 -
 liblwgeom/lwcollection.c | 11 +++--------
 liblwgeom/lwline.c       | 15 ++-------------
 liblwgeom/lwpoly.c       |  2 +-
 4 files changed, 6 insertions(+), 23 deletions(-)

diff --git a/NEWS b/NEWS
index bcb738eb5..6375a03db 100644
--- a/NEWS
+++ b/NEWS
@@ -13,7 +13,6 @@ PostGIS 2.1.0
   - ST_Slope and ST_Aspect return pixel values in degrees instead of radians.
   - #1653, Removed srid parameter from ST_Resample(raster) and variants
     with reference raster no longer apply reference raster's SRID.
-  - ST_Simplify returns NULL on EMPTY input or single-vertex line output
 
 * Deprecated signatures
 
diff --git a/liblwgeom/lwcollection.c b/liblwgeom/lwcollection.c
index d33d70901..fd95b7dbd 100644
--- a/liblwgeom/lwcollection.c
+++ b/liblwgeom/lwcollection.c
@@ -496,20 +496,15 @@ int lwcollection_count_vertices(LWCOLLECTION *col)
 LWCOLLECTION* lwcollection_simplify(const LWCOLLECTION *igeom, double dist)
 {
  	int i;
-	LWCOLLECTION *out = NULL;
+	LWCOLLECTION *out = lwcollection_construct_empty(igeom->type, igeom->srid, FLAGS_GET_Z(igeom->flags), FLAGS_GET_M(igeom->flags));
 
 	if( lwcollection_is_empty(igeom) )
-		return NULL;
+		return out; /* should we return NULL instead ? */
 
 	for( i = 0; i < igeom->ngeoms; i++ )
 	{
 		LWGEOM *ngeom = lwgeom_simplify(igeom->geoms[i], dist);
-		if ( ngeom ) {
-			if ( ! out ) {
-				out = lwcollection_construct_empty(igeom->type, igeom->srid, FLAGS_GET_Z(igeom->flags), FLAGS_GET_M(igeom->flags));
-			}
-			out = lwcollection_add_lwgeom(out, ngeom);
-		}
+		if ( ngeom ) out = lwcollection_add_lwgeom(out, ngeom);
 	}
 
 	return out;
diff --git a/liblwgeom/lwline.c b/liblwgeom/lwline.c
index fc378b166..30de4ad41 100644
--- a/liblwgeom/lwline.c
+++ b/liblwgeom/lwline.c
@@ -473,26 +473,15 @@ int lwline_count_vertices(LWLINE *line)
 LWLINE* lwline_simplify(const LWLINE *iline, double dist)
 {
 	LWLINE *oline;
-	POINTARRAY *opts;
 
 	LWDEBUG(2, "function called");
 
 	/* Skip empty case */
 	if( lwline_is_empty(iline) )
-		return NULL;
+		return lwline_clone(iline);
 		
 	static const int minvertices = 0; /* TODO: allow setting this */
-	opts = ptarray_simplify(iline->points, dist, minvertices);
-
-	/* Less points than are needed to form a line, we can't use this */
-	if ( opts->npoints < 2 )
-	{
-			LWDEBUGF(3, "line skipped (% pts)", opts->npoints);
-			ptarray_free(opts);
-			return NULL;
-	}
-
-	oline = lwline_construct(iline->srid, NULL, opts);
+	oline = lwline_construct(iline->srid, NULL, ptarray_simplify(iline->points, dist, minvertices));
 	oline->type = iline->type;
 	return oline;
 }
diff --git a/liblwgeom/lwpoly.c b/liblwgeom/lwpoly.c
index abe9e4f59..52c27fad9 100644
--- a/liblwgeom/lwpoly.c
+++ b/liblwgeom/lwpoly.c
@@ -350,7 +350,7 @@ LWPOLY* lwpoly_simplify(const LWPOLY *ipoly, double dist)
 	LWDEBUGF(2, "simplify_polygon3d: simplifying polygon with %d rings", ipoly->nrings);
 
 	if( lwpoly_is_empty(ipoly) )
-		return NULL;
+		return opoly; /* should we return NULL instead ? */
 
 	for (i = 0; i < ipoly->nrings; i++)
 	{
-- 
2.50.1