lwgeom_delaunay_triangulation()

LWGEOM* lwgeom_delaunay_triangulation	(	const LWGEOM *	geom,
		double	tolerance,
		int32_t	edgeOnly
	)

Take vertices of a geometry and build a delaunay triangulation on them.

Parameters

geom	the input geometry
tolerance	an optional snapping tolerance for improved robustness
edgeOnly	if non-zero the result will be a MULTILINESTRING, otherwise it'll be a COLLECTION of polygons.

Definition at line 1788 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;
 
        if (output < 0 || output > 2)
        {
                lwerror("%s: invalid output type specified %d", __func__, output);
                return NULL;
        }
 
        if (srid == SRID_INVALID) return NULL;
 
        initGEOS(lwnotice, lwgeom_geos_error);
 
        if (!(g1 = LWGEOM2GEOS(geom, AUTOFIX))) GEOS_FAIL();
 
        /* if output != 1 we want polys */
        g3 = GEOSDelaunayTriangulation(g1, tolerance, output == 1);
 
        if (!g3) GEOS_FREE_AND_FAIL(g1);
        GEOSSetSRID(g3, srid);
 
        if (output == 2)
        {
                result = (LWGEOM*)lwtin_from_geos(g3, is3d);
                if (!result)
                {
                        GEOS_FREE(g1, g3);
                        lwerror("%s: cannot convert output geometry", __func__);
                        return NULL;
                }
                lwgeom_set_srid(result, srid);
        }
        else 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, lwerror(), LWGEOM2GEOS(), lwgeom_geos_error(), lwgeom_set_srid(), lwnotice(), lwtin_from_geos(), RESULT_SRID, and SRID_INVALID.

Referenced by ST_DelaunayTriangles(), and test_lwgeom_delaunay_triangulation().

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