Returns true if a geometry object has no self-intersections; returns false otherwise.
Syntax
boolean ST_IsSimple(geometry geomA);Parameters
| Parameter | Description |
|---|---|
geomA | The geometry object to evaluate. |
Description
This function supports 3D geometries and preserves Z coordinates.
Examples
Simple geometry (returns `true`)
The following LINESTRING forms a closed triangle. Each segment meets only at endpoints, so no self-intersection exists.
SELECT ST_IsSimple('LINESTRING(0 0,0 2,2 0,0 0)'::geometry);
st_issimple
-------------
t
(1 row)Non-simple geometry (returns `false`)
The following LINESTRING retraces its path, meaning the line crosses itself at the start point. This creates a self-intersection that violates the simplicity condition.
SELECT ST_IsSimple('LINESTRING(0 0,0 2,0 0)'::geometry);
st_issimple
-------------
f
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