lwmline_clip_to_ordinate_range()

LWCOLLECTION* lwmline_clip_to_ordinate_range	(	const LWMLINE *	mline,
		char	ordinate,
		double	from,
		double	to
	)

Clip an input MULTILINESTRING between two values, on any ordinate input.

Clip a multi-line based on the from/to range of one of its ordinates.

Definition at line 468 of file lwlinearreferencing.c.

{
        LWCOLLECTION *lwgeom_out = NULL;
 
        if ( ! mline )
        {
                lwerror("Null input geometry.");
                return NULL;
        }
 
        if ( mline->ngeoms == 1)
        {
                lwgeom_out = lwline_clip_to_ordinate_range(mline->geoms[0], ordinate, from, to);
        }
        else
        {
                LWCOLLECTION *col;
                char hasz = lwgeom_has_z(lwmline_as_lwgeom(mline));
                char hasm = lwgeom_has_m(lwmline_as_lwgeom(mline));
                uint32_t i, j;
                char homogeneous = 1;
                size_t geoms_size = 0;
                lwgeom_out = lwcollection_construct_empty(MULTILINETYPE, mline->srid, hasz, hasm);
                FLAGS_SET_Z(lwgeom_out->flags, hasz);
                FLAGS_SET_M(lwgeom_out->flags, hasm);
                for ( i = 0; i < mline->ngeoms; i ++ )
                {
                        col = lwline_clip_to_ordinate_range(mline->geoms[i], ordinate, from, to);
                        if ( col )
                        {
                                /* Something was left after the clip. */
                                if ( lwgeom_out->ngeoms + col->ngeoms > geoms_size )
                                {
                                        geoms_size += 16;
                                        if ( lwgeom_out->geoms )
                                        {
                                                lwgeom_out->geoms = lwrealloc(lwgeom_out->geoms, geoms_size * sizeof(LWGEOM*));
                                        }
                                        else
                                        {
                                                lwgeom_out->geoms = lwalloc(geoms_size * sizeof(LWGEOM*));
                                        }
                                }
                                for ( j = 0; j < col->ngeoms; j++ )
                                {
                                        lwgeom_out->geoms[lwgeom_out->ngeoms] = col->geoms[j];
                                        lwgeom_out->ngeoms++;
                                }
                                if ( col->type != mline->type )
                                {
                                        homogeneous = 0;
                                }
                                /* Shallow free the struct, leaving the geoms behind. */
                                if ( col->bbox ) lwfree(col->bbox);
                                lwfree(col->geoms);
                                lwfree(col);
                        }
                }
                if ( lwgeom_out->bbox )
                {
                        lwgeom_refresh_bbox((LWGEOM*)lwgeom_out);
                }
 
                if ( ! homogeneous )
                {
                        lwgeom_out->type = COLLECTIONTYPE;
                }
        }
 
        return lwgeom_out;
 
}

References LWCOLLECTION::bbox, COLLECTIONTYPE, LWCOLLECTION::flags, FLAGS_SET_M, FLAGS_SET_Z, LWMLINE::geoms, LWCOLLECTION::geoms, lwalloc(), lwcollection_construct_empty(), lwerror(), lwfree(), lwgeom_has_m(), lwgeom_has_z(), lwgeom_refresh_bbox(), lwline_clip_to_ordinate_range(), lwmline_as_lwgeom(), lwrealloc(), MULTILINETYPE, LWMLINE::ngeoms, LWCOLLECTION::ngeoms, LWMLINE::srid, LWMLINE::type, and LWCOLLECTION::type.

Referenced by lwgeom_clip_to_ordinate_range(), and test_lwmline_clip().

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