lwgeom_simplify_polygonal()

LWGEOM* lwgeom_simplify_polygonal	(	const LWGEOM *	geom,
		double	vertex_fraction,
		uint32_t	is_outer
	)

Computes a boundary-respecting hull of a polygonal geometry, with hull shape determined by a target parameter specifying the fraction of the input vertices retained in the result.

Larger values produce less concave results.

Parameters

geom	the input geometry
vertex_fraction	proportion of vertices in output vs input.
is_outer	expand geometry while removing edges.

Definition at line 2185 of file liblwgeom/lwgeom_geos.c.

{
        LWGEOM* result;
        int32_t srid = RESULT_SRID(geom);
        uint8_t is3d = FLAGS_GET_Z(geom->flags);
        GEOSGeometry *g1, *g3;
 
        initGEOS(lwnotice, lwgeom_geos_error);
 
        if (!(g1 = LWGEOM2GEOS(geom, AUTOFIX))) GEOS_FAIL();
 
        g3 = GEOSPolygonHullSimplify(g1, is_outer, vertex_fraction);
 
        if (!g3)
                GEOS_FREE_AND_FAIL(g1);
 
        GEOSSetSRID(g3, srid);
 
        if (!(result = GEOS2LWGEOM(g3, is3d)))
                GEOS_FREE_AND_FAIL(g1, g3);
 
        GEOS_FREE(g1, g3);
        return result;
}

References AUTOFIX, LWGEOM::flags, FLAGS_GET_Z, GEOS2LWGEOM(), GEOS_FAIL, GEOS_FREE, GEOS_FREE_AND_FAIL, LWGEOM2GEOS(), lwgeom_geos_error(), lwnotice(), result, and RESULT_SRID.

Referenced by ST_SimplifyPolygonHull().

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