From: Paul Ramsey <pramsey@cleverelephant.ca>
Date: Thu, 12 Jan 2012 21:43:56 +0000 (+0000)
Subject: Add in an offset option to ST_LocateBetween
X-Git-Tag: 2.0.0alpha1~86
X-Git-Url: https://granicus.if.org/sourcecode?a=commitdiff_plain;h=6f1e0a2f48b0e7ec8d4b98bf7294a6744c8821b2;p=postgis

Add in an offset option to ST_LocateBetween


git-svn-id: http://svn.osgeo.org/postgis/trunk@8794 b70326c6-7e19-0410-871a-916f4a2858ee
---

diff --git a/liblwgeom/liblwgeom.h.in b/liblwgeom/liblwgeom.h.in
index 524861ddb..e3c53cc73 100644
--- a/liblwgeom/liblwgeom.h.in
+++ b/liblwgeom/liblwgeom.h.in
@@ -1272,7 +1272,7 @@ int lwline_crossing_direction(const LWLINE *l1, const LWLINE *l2);
 /**
 * Given a geometry clip  based on the from/to range of one of its ordinates (x, y, z, m). Use for m- and z- clipping.
 */
-LWCOLLECTION* lwgeom_clip_to_ordinate_range(const LWGEOM *lwin, char ordinate, double from, double to);
+LWCOLLECTION* lwgeom_clip_to_ordinate_range(const LWGEOM *lwin, char ordinate, double from, double to, double offset);
 
 /*
  * Export functions
diff --git a/liblwgeom/lwlinearreferencing.c b/liblwgeom/lwlinearreferencing.c
index ae67086da..988e13147 100644
--- a/liblwgeom/lwlinearreferencing.c
+++ b/liblwgeom/lwlinearreferencing.c
@@ -740,24 +740,70 @@ lwline_clip_to_ordinate_range(const LWLINE *line, char ordinate, double from, do
 }
 
 LWCOLLECTION*
-lwgeom_clip_to_ordinate_range(const LWGEOM *lwin, char ordinate, double from, double to)
+lwgeom_clip_to_ordinate_range(const LWGEOM *lwin, char ordinate, double from, double to, double offset)
 {
+	LWCOLLECTION *out_col;
+	LWCOLLECTION *out_offset;
+	int i;
+	
 	if ( ! lwin )
 		lwerror("lwgeom_clip_to_ordinate_range: null input geometry!");
 		
 	switch ( lwin->type )
 	{
 		case LINETYPE:
-			return lwline_clip_to_ordinate_range((LWLINE*)lwin, ordinate, from, to);
+			out_col = lwline_clip_to_ordinate_range((LWLINE*)lwin, ordinate, from, to);
+			break;
 		case MULTILINETYPE:
-			return lwmline_clip_to_ordinate_range((LWMLINE*)lwin, ordinate, from, to);
+			out_col = lwmline_clip_to_ordinate_range((LWMLINE*)lwin, ordinate, from, to);
+			break;
 		case MULTIPOINTTYPE:
-			return lwmpoint_clip_to_ordinate_range((LWMPOINT*)lwin, ordinate, from, to);
+			out_col = lwmpoint_clip_to_ordinate_range((LWMPOINT*)lwin, ordinate, from, to);
+			break;
 		case POINTTYPE:
-			return lwpoint_clip_to_ordinate_range((LWPOINT*)lwin, ordinate, from, to);
+			out_col = lwpoint_clip_to_ordinate_range((LWPOINT*)lwin, ordinate, from, to);
+			break;
 		default:
 			lwerror("This function does not accept %s geometries.", lwtype_name(lwin->type));
+			return NULL;;
+	}
+	
+	/* Stop if result is NULL */
+	if ( out_col == NULL )
+		lwerror("lwgeom_clip_to_ordinate_range clipping routine returned NULL");
+	
+	/* Return if we aren't going to offset the result */
+	if ( FP_EQUALS(offset, 0.0) || lwgeom_is_empty(lwcollection_as_lwgeom(out_col)) )
+		return out_col;
+	
+	/* Construct a collection to hold our outputs. */
+	/* Things get ugly: GEOS offset drops Z's and M's so we have to drop ours */
+	out_offset = lwcollection_construct_empty(MULTILINETYPE, lwin->srid, 0, 0);
+	
+	/* Try and offset the linear portions of the return value */
+	for ( i = 0; i < out_col->ngeoms; i++ )
+	{
+		int type = out_col->geoms[i]->type;
+		if ( type == POINTTYPE )
+		{
+			lwnotice("lwgeom_clip_to_ordinate_range cannot offset a clipped point");
+			continue;
+		}
+		else if ( type == LINETYPE )
+		{
+			/* lwgeom_offsetcurve(line, offset, quadsegs, joinstyle (round), mitrelimit) */
+			LWGEOM *lwoff = lwgeom_offsetcurve(lwgeom_as_lwline(out_col->geoms[i]), offset, 8, 1, 5.0);
+			if ( ! lwoff )
+			{
+				lwerror("lwgeom_offsetcurve returned null");
+			}
+			lwcollection_add_lwgeom(out_offset, lwoff);
+		}
+		else 
+		{
+			lwerror("lwgeom_clip_to_ordinate_range found an unexpected type (%s) in the offset routine",lwtype_name(type));
+		}
 	}
 
-	return NULL;
+	return out_offset;
 }
diff --git a/postgis/lwgeom_functions_lrs.c b/postgis/lwgeom_functions_lrs.c
index 8e55c3f44..a39abbf87 100644
--- a/postgis/lwgeom_functions_lrs.c
+++ b/postgis/lwgeom_functions_lrs.c
@@ -610,10 +610,10 @@ Datum ST_LocateBetween(PG_FUNCTION_ARGS)
 	}
 
 	line_in = lwgeom_from_gserialized(geom_in);
-	geom_out = lwgeom_clip_to_ordinate_range(line_in,  ordinate, from, to);	
+	geom_out = lwgeom_clip_to_ordinate_range(line_in,  ordinate, from, to, offset);	
 	lwgeom_free(line_in);
 	PG_FREE_IF_COPY(geom_in, 0);
-
+	
 	if ( ! geom_out )
 	{
 		elog(ERROR,"lwline_clip_to_ordinate_range returned null");
@@ -636,6 +636,7 @@ Datum ST_LocateBetweenElevations(PG_FUNCTION_ARGS)
 	LWCOLLECTION *geom_out = NULL;
 	LWGEOM *line_in = NULL;
 	static char ordinate = 'Z'; /* Z */
+	static double offset = 0.0;
 
 	if ( ! gserialized_has_z(geom_in) )
 	{
@@ -644,7 +645,7 @@ Datum ST_LocateBetweenElevations(PG_FUNCTION_ARGS)
 	}
 
 	line_in = lwgeom_from_gserialized(geom_in);
-	geom_out = lwgeom_clip_to_ordinate_range(line_in,  ordinate, from, to);	
+	geom_out = lwgeom_clip_to_ordinate_range(line_in,  ordinate, from, to, offset);	
 	lwgeom_free(line_in);
 	PG_FREE_IF_COPY(geom_in, 0);