ST_IsPolygonCW

ST_IsPolygonCW returns true if the 2D projection of the input polygon or multipolygon is clockwise. If the input geometry is a point, linestring, multipoint, or multilinestring, then true is returned. For geometry collections, ST_IsPolygonCW returns true if all the geometries in the collection are clockwise.

Syntax

ST_IsPolygonCW(geom)

Arguments

geom

A value of data type GEOMETRY or an expression that evaluates to a GEOMETRY type.

Return type

BOOLEAN

If geom is null, then null is returned.

Examples

The following SQL checks if the polygon is clockwise.

SELECT ST_IsPolygonCW(ST_GeomFromText('POLYGON((7 9,8 7,11 6,15 8,16 6,17 7,17 10,18 12,17 14,15 15,11 15,10 13,9 12,7 9),(9 9,10 10,11 11,11 10,10 8,9 9),(12 14,15 14,13 11,12 14))'));

 st_ispolygonccw
----------
 true