ST_IsPolygonCW

Syntax

boolean ST_IsPolygonCW(geometry geom);

Parameters

Description

ST_IsPolygonCW returns true if all exterior rings of the input polygon are orientated clockwise and all interior rings are orientated anticlockwise.

The function also supports 3D objects (Z coordinates are preserved) and M coordinates.

If the input contains no polygon components (for example, a Point or a LineString), the function returns true. A closed LineString is not treated as a polygon component.

If one or more interior rings are orientated in the same direction as an exterior ring, both ST_IsPolygonCW and ST_IsPolygonCCW return false.

Examples

Check whether a polygon's rings are in clockwise orientation:

SELECT ST_IsPolygonCW('POLYGON((1 0,0 3,3 0,1 0),(1 0,2 0,0 2,1 0))'::geometry);
 st_ispolygoncw
----------------
 t
(1 row)

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