From: Paul Ramsey <pramsey@cleverelephant.ca>
Date: Wed, 22 Jul 2015 16:03:10 +0000 (+0000)
Subject: #3172, ST_AddMeasure refuses to set measure of zero-length line
X-Git-Tag: 2.2.0rc1~228
X-Git-Url: https://granicus.if.org/sourcecode?a=commitdiff_plain;h=1e54b2a7ee02afe0834802b013a5a093ee30b1b4;p=postgis

#3172, ST_AddMeasure refuses to set measure of zero-length line


git-svn-id: http://svn.osgeo.org/postgis/trunk@13830 b70326c6-7e19-0410-871a-916f4a2858ee
---

diff --git a/liblwgeom/lwline.c b/liblwgeom/lwline.c
index 582ac91f6..58f0d6727 100644
--- a/liblwgeom/lwline.c
+++ b/liblwgeom/lwline.c
@@ -407,6 +407,9 @@ lwline_measured_from_lwline(const LWLINE *lwline, double m_start, double m_end)
 		length_so_far += distance2d_pt_pt(&a, &b);
 		if ( length > 0.0 )
 			m = m_start + m_range * length_so_far / length;
+		/* #3172, support (valid) zero-length inputs */
+		else if ( length == 0.0 && npoints > 1 )
+			m = m_start + m_range * i / (npoints-1);
 		else
 			m = 0.0;
 		q.x = p2.x;
diff --git a/regress/tickets.sql b/regress/tickets.sql
index 4c99a9533..71687bd3e 100644
--- a/regress/tickets.sql
+++ b/regress/tickets.sql
@@ -906,5 +906,7 @@ SELECT '#2870', ST_Summary('Point(151.215289 -33.856885)'::geometry::bytea::geog
 
 SELECT '#2956', st_astwkb(null,0) is null;
 
+SELECT '#3172', ST_AsText(ST_AddMeasure('LINESTRING(0 0,0 0)', 1, 2));
+
 -- Clean up
 DELETE FROM spatial_ref_sys;
diff --git a/regress/tickets_expected b/regress/tickets_expected
index ae4b42dd2..860cdc2e1 100644
--- a/regress/tickets_expected
+++ b/regress/tickets_expected
@@ -265,3 +265,4 @@ ERROR:  invalid GML representation
 #2788|f|Self-intersection|POINT(1 1)
 #2870|Point[GS]
 #2956|t
+#3172|LINESTRING M (0 0 1,0 0 2)