Add zDirection to options

src/ol/source/UTFGrid.js

@@ -268,6 +268,9 @@ export class CustomTile extends Tile {
  * If not provided, `url` must be configured.
  * @property {string} [url] TileJSON endpoint that provides the configuration for this source.
  * Request will be made through JSONP. If not provided, `tileJSON` must be configured.
+ * @property {number|import("../array.js").NearestDirectionFunction} [zDirection=0]
+ * Choose whether to use tiles with a higher or lower zoom level when between integer
+ * zoom levels. See {@link module:ol/tilegrid/TileGrid~TileGrid#getZForResolution}.
  */
 
 /**
@@ -283,6 +286,7 @@ class UTFGrid extends TileSource {
     super({
       projection: getProjection('EPSG:3857'),
       state: SourceState.LOADING,
+      zDirection: options.zDirection,
     });
 
     /**