lwgeom_interpolate_point()

double lwgeom_interpolate_point	(	const LWGEOM *	lwin,
		const LWPOINT *	lwpt
	)

Find the measure value at the location on the line closest to the point.

Definition at line 851 of file lwlinearreferencing.c.

References LINETYPE, lwerror(), lwgeom_as_lwline(), lwgeom_has_m(), lwgeom_is_empty(), lwpoint_getPoint4d_p(), lwpoint_is_empty(), lwtype_name(), POINT4D::m, LWLINE::points, ptarray_locate_point(), and LWGEOM::type.

Referenced by gserialized_distance_nd(), and ST_InterpolatePoint().

{
        POINT4D p, p_proj;
        double ret = 0.0;

        if ( ! lwin )
                lwerror("lwgeom_interpolate_point: null input geometry!");

        if ( ! lwgeom_has_m(lwin) )
                lwerror("Input geometry does not have a measure dimension");

        if ( lwgeom_is_empty(lwin) || lwpoint_is_empty(lwpt) )
                lwerror("Input geometry is empty");

        switch ( lwin->type )
        {
        case LINETYPE:
        {
                LWLINE *lwline = lwgeom_as_lwline(lwin);
                lwpoint_getPoint4d_p(lwpt, &p);
                ret = ptarray_locate_point(lwline->points, &p, NULL, &p_proj);
                ret = p_proj.m;
                break;
        }
        default:
                lwerror("This function does not accept %s geometries.", lwtype_name(lwin->type));
        }
        return ret;
}

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