Add point <-> polygon distance operator.

Alexander Korotkov, reviewed by Emre Hasegeli.

src/backend/utils/adt/geo_ops.c

@@ -73,6 +73,7 @@ static double dist_ps_internal(Point *pt, LSEG *lseg);
 static Point *line_interpt_internal(LINE *l1, LINE *l2);
 static bool lseg_inside_poly(Point *a, Point *b, POLYGON *poly, int start);
 static Point *lseg_interpt_internal(LSEG *l1, LSEG *l2);
+static double dist_ppoly_internal(Point *pt, POLYGON *poly);
 
 
 /*
@@ -2415,6 +2416,9 @@ lseg_interpt(PG_FUNCTION_ARGS)
  *				Minimum distance from one object to another.
  *-------------------------------------------------------------------*/
 
+/*
+ * Distance from a point to a line
+ */
 Datum
 dist_pl(PG_FUNCTION_ARGS)
 {
@@ -2431,6 +2435,9 @@ dist_pl_internal(Point *pt, LINE *line)
 				HYPOT(line->A, line->B));
 }
 
+/*
+ * Distance from a point to a lseg
+ */
 Datum
 dist_ps(PG_FUNCTION_ARGS)
 {
@@ -2494,7 +2501,7 @@ dist_ps_internal(Point *pt, LSEG *lseg)
 }
 
 /*
- ** Distance from a point to a path
+ * Distance from a point to a path
  */
 Datum
 dist_ppath(PG_FUNCTION_ARGS)
@@ -2550,6 +2557,9 @@ dist_ppath(PG_FUNCTION_ARGS)
 	PG_RETURN_FLOAT8(result);
 }
 
+/*
+ * Distance from a point to a box
+ */
 Datum
 dist_pb(PG_FUNCTION_ARGS)
 {
@@ -2566,7 +2576,9 @@ dist_pb(PG_FUNCTION_ARGS)
 	PG_RETURN_FLOAT8(result);
 }
 
-
+/*
+ * Distance from a lseg to a line
+ */
 Datum
 dist_sl(PG_FUNCTION_ARGS)
 {
@@ -2589,7 +2601,9 @@ dist_sl(PG_FUNCTION_ARGS)
 	PG_RETURN_FLOAT8(result);
 }
 
-
+/*
+ * Distance from a lseg to a box
+ */
 Datum
 dist_sb(PG_FUNCTION_ARGS)
 {
@@ -2608,7 +2622,9 @@ dist_sb(PG_FUNCTION_ARGS)
 	PG_RETURN_DATUM(result);
 }
 
-
+/*
+ * Distance from a line to a box
+ */
 Datum
 dist_lb(PG_FUNCTION_ARGS)
 {
@@ -2625,21 +2641,53 @@ dist_lb(PG_FUNCTION_ARGS)
 	PG_RETURN_NULL();
 }
 
-
+/*
+ * Distance from a circle to a polygon
+ */
 Datum
 dist_cpoly(PG_FUNCTION_ARGS)
 {
 	CIRCLE	   *circle = PG_GETARG_CIRCLE_P(0);
 	POLYGON    *poly = PG_GETARG_POLYGON_P(1);
 	float8		result;
+
+	/* calculate distance to center, and subtract radius */
+	result = dist_ppoly_internal(&circle->center, poly);
+
+	result -= circle->radius;
+	if (result < 0)
+		result = 0;
+
+	PG_RETURN_FLOAT8(result);
+}
+
+/*
+ * Distance from a point to a polygon
+ */
+Datum
+dist_ppoly(PG_FUNCTION_ARGS)
+{
+	Point	   *point = PG_GETARG_POINT_P(0);
+	POLYGON    *poly = PG_GETARG_POLYGON_P(1);
+	float8		result;
+
+	result = dist_ppoly_internal(point, poly);
+
+	PG_RETURN_FLOAT8(result);
+}
+
+static double
+dist_ppoly_internal(Point *pt, POLYGON *poly)
+{
+	float8		result;
 	float8		d;
 	int			i;
 	LSEG		seg;
 
-	if (point_inside(&(circle->center), poly->npts, poly->p) != 0)
+	if (point_inside(pt, poly->npts, poly->p) != 0)
 	{
 #ifdef GEODEBUG
-		printf("dist_cpoly- center inside of polygon\n");
+		printf("dist_ppoly_internal- point inside of polygon\n");
 #endif
 		PG_RETURN_FLOAT8(0.0);
 	}
@@ -2649,9 +2697,9 @@ dist_cpoly(PG_FUNCTION_ARGS)
 	seg.p[0].y = poly->p[0].y;
 	seg.p[1].x = poly->p[poly->npts - 1].x;
 	seg.p[1].y = poly->p[poly->npts - 1].y;
-	result = dist_ps_internal(&circle->center, &seg);
+	result = dist_ps_internal(pt, &seg);
 #ifdef GEODEBUG
-	printf("dist_cpoly- segment 0/n distance is %f\n", result);
+	printf("dist_ppoly_internal- segment 0/n distance is %f\n", result);
 #endif
 
 	/* check distances for other segments */
@@ -2661,19 +2709,15 @@ dist_cpoly(PG_FUNCTION_ARGS)
 		seg.p[0].y = poly->p[i].y;
 		seg.p[1].x = poly->p[i + 1].x;
 		seg.p[1].y = poly->p[i + 1].y;
-		d = dist_ps_internal(&circle->center, &seg);
+		d = dist_ps_internal(pt, &seg);
 #ifdef GEODEBUG
-		printf("dist_cpoly- segment %d distance is %f\n", (i + 1), d);
+		printf("dist_ppoly_internal- segment %d distance is %f\n", (i + 1), d);
 #endif
 		if (d < result)
 			result = d;
 	}
 
-	result -= circle->radius;
-	if (result < 0)
-		result = 0;
-
-	PG_RETURN_FLOAT8(result);
+	return result;
 }
 
 

src/include/catalog/pg_operator.h

@@ -1016,6 +1016,8 @@ DATA(insert OID = 1521 (  "#"	  PGNSP PGUID l f f  0		604   23	  0    0 poly_npo
 DESCR("number of points");
 DATA(insert OID = 1522 (  "<->"   PGNSP PGUID b f f  600	718  701	  0    0 dist_pc - - ));
 DESCR("distance between");
+DATA(insert OID = 3276 (  "<->"	  PGNSP PGUID b f f	 600	604	 701	  0	   0 dist_ppoly - - ));
+DESCR("distance between");
 DATA(insert OID = 1523 (  "<->"   PGNSP PGUID b f f  718	604  701	  0    0 dist_cpoly - - ));
 DESCR("distance between");
 

src/include/catalog/pg_proc.h

@@ -844,6 +844,7 @@ DATA(insert OID = 726 (  dist_lb		   PGNSP PGUID 12 1 0 0 0 f f f f t f i 2 0 70
 DATA(insert OID = 727 (  dist_sl		   PGNSP PGUID 12 1 0 0 0 f f f f t f i 2 0 701 "601 628" _null_ _null_ _null_ _null_	dist_sl _null_ _null_ _null_ ));
 DATA(insert OID = 728 (  dist_cpoly		   PGNSP PGUID 12 1 0 0 0 f f f f t f i 2 0 701 "718 604" _null_ _null_ _null_ _null_	dist_cpoly _null_ _null_ _null_ ));
 DATA(insert OID = 729 (  poly_distance	   PGNSP PGUID 12 1 0 0 0 f f f f t f i 2 0 701 "604 604" _null_ _null_ _null_ _null_	poly_distance _null_ _null_ _null_ ));
+DATA(insert OID = 3275 (  dist_ppoly	   PGNSP PGUID 12 1 0 0 0 f f f f t f i 2 0 701 "600 604" _null_ _null_ _null_ _null_	dist_ppoly _null_ _null_ _null_ ));
 
 DATA(insert OID = 740 (  text_lt		   PGNSP PGUID 12 1 0 0 0 f f f f t f i 2 0 16 "25 25" _null_ _null_ _null_ _null_ text_lt _null_ _null_ _null_ ));
 DATA(insert OID = 741 (  text_le		   PGNSP PGUID 12 1 0 0 0 f f f f t f i 2 0 16 "25 25" _null_ _null_ _null_ _null_ text_le _null_ _null_ _null_ ));

src/include/utils/geo_decls.h

@@ -395,6 +395,7 @@ extern Datum circle_radius(PG_FUNCTION_ARGS);
 extern Datum circle_distance(PG_FUNCTION_ARGS);
 extern Datum dist_pc(PG_FUNCTION_ARGS);
 extern Datum dist_cpoly(PG_FUNCTION_ARGS);
+extern Datum dist_ppoly(PG_FUNCTION_ARGS);
 extern Datum circle_center(PG_FUNCTION_ARGS);
 extern Datum cr_circle(PG_FUNCTION_ARGS);
 extern Datum box_circle(PG_FUNCTION_ARGS);

src/test/regress/expected/polygon.out

@@ -279,3 +279,14 @@ SELECT '((200,800),(800,800),(800,200),(200,200))' &&  '(1000,1000,0,0)'::polygo
  t
 (1 row)
 
+-- distance from a point
+SELECT	'(0,0)'::point <-> '((0,0),(1,2),(2,1))'::polygon as on_corner,
+	'(1,1)'::point <-> '((0,0),(2,2),(1,3))'::polygon as on_segment,
+	'(2,2)'::point <-> '((0,0),(1,4),(3,1))'::polygon as inside,
+	'(3,3)'::point <-> '((0,2),(2,0),(2,2))'::polygon as near_corner,
+	'(4,4)'::point <-> '((0,0),(0,3),(4,0))'::polygon as near_segment;
+ on_corner | on_segment | inside |   near_corner   | near_segment 
+-----------+------------+--------+-----------------+--------------
+         0 |          0 |      0 | 1.4142135623731 |          3.2
+(1 row)
+

src/test/regress/sql/polygon.sql

@@ -172,3 +172,10 @@ SELECT '((0,4),(6,4),(1,2),(6,0),(0,0))'::polygon && '((2,1),(2,3),(3,3),(3,1))'
 --     +-------+
 SELECT '((1,4),(1,1),(4,1),(4,2),(2,2),(2,4),(1,4))'::polygon && '((3,3),(4,3),(4,4),(3,4),(3,3))'::polygon AS "false";
 SELECT '((200,800),(800,800),(800,200),(200,200))' &&  '(1000,1000,0,0)'::polygon AS "true";
+
+-- distance from a point
+SELECT	'(0,0)'::point <-> '((0,0),(1,2),(2,1))'::polygon as on_corner,
+	'(1,1)'::point <-> '((0,0),(2,2),(1,3))'::polygon as on_segment,
+	'(2,2)'::point <-> '((0,0),(1,4),(3,1))'::polygon as inside,
+	'(3,3)'::point <-> '((0,2),(2,0),(2,2))'::polygon as near_corner,
+	'(4,4)'::point <-> '((0,0),(0,3),(4,0))'::polygon as near_segment;