load( url, onLoad, onProgress, onError ) {

		const scope = this;

		const loader = new FileLoader( this.manager );
		loader.setPath( this.path );
		loader.setRequestHeader( this.requestHeader );
		loader.setWithCredentials( this.withCredentials );
		loader.load( url, function ( text ) {

			try {

				onLoad( scope.parse( text ) );

			} catch ( e ) {

				if ( onError ) {

					onError( e );

				} else {

					console.error( e );

				}

				scope.manager.itemError( url );

			}

		}, onProgress, onError );

	}
Starts loading from the given URL and passes the loaded OBJ asset
to the `onLoad()` callback.

@param {string} url - The path/URL of the file to be loaded. This can also be a data URI.
@param {function(Group)} onLoad - Executed when the loading process has been finished.
@param {onProgressCallback} onProgress - Executed while the loading is in progress.
@param {onErrorCallback} onError - Executed when errors occur.