PostGIS

ST_IsPolygonCCW

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8.4. Geometry Accessors

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Name

ST_IsPolygonCCW — Tests if Polygons have exterior rings oriented counter-clockwise and interior rings oriented clockwise.

Synopsis

+ boolean `*`+ST_IsPolygonCCW*+ (` geometry `+geom );

Description

Returns true if all polygonal components of the input geometry use a counter-clockwise orientation for their exterior ring, and a clockwise direction for all interior rings.

Returns true if the geometry has no polygonal components.

Note

Closed linestrings are not considered polygonal components, so you would still get a true return by passing a single closed linestring no matter its orientation.
Note

If a polygonal geometry does not use reversed orientation for interior rings (i.e., if one or more interior rings are oriented in the same direction as an exterior ring) then both ST_IsPolygonCW and ST_IsPolygonCCW will return false.

Availability: 2.4.0

check This function supports 3d and will not drop the z-index.

check This function supports M coordinates.

See Also

ST_ForcePolygonCW , ST_ForcePolygonCCW , ST_IsPolygonCW

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ST_IsPolygonCW