lwgeom_locate_along()

LWGEOM* lwgeom_locate_along	(	const LWGEOM *	lwin,
		double	m,
		double	offset
	)

Determine the location(s) along a measured line where m occurs and return as a multipoint.

Offset to left (positive) or right (negative).

Definition at line 219 of file lwlinearreferencing.c.

{
        if (!lwin)
                return NULL;
 
        if (!lwgeom_has_m(lwin))
                lwerror("Input geometry does not have a measure dimension");
 
        switch (lwin->type)
        {
        case POINTTYPE:
                return (LWGEOM *)lwpoint_locate_along((LWPOINT *)lwin, m, offset);
        case MULTIPOINTTYPE:
                return (LWGEOM *)lwmpoint_locate_along((LWMPOINT *)lwin, m, offset);
        case LINETYPE:
                return (LWGEOM *)lwline_locate_along((LWLINE *)lwin, m, offset);
        case MULTILINETYPE:
                return (LWGEOM *)lwmline_locate_along((LWMLINE *)lwin, m, offset);
        /* Only line types supported right now */
        /* TO DO: CurveString, CompoundCurve, MultiCurve */
        /* TO DO: Point, MultiPoint */
        default:
                lwerror("Only linear geometries are supported, %s provided.", lwtype_name(lwin->type));
                return NULL;
        }
        return NULL;
}

References LINETYPE, lwerror(), lwgeom_has_m(), lwline_locate_along(), lwmline_locate_along(), lwmpoint_locate_along(), lwpoint_locate_along(), lwtype_name(), MULTILINETYPE, MULTIPOINTTYPE, POINTTYPE, LWGEOM::type, and LWPOINT::type.

Referenced by ST_LocateAlong(), and test_lwgeom_locate_along().

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