unregister( callback ) {

		if ( this.pluginCallbacks.indexOf( callback ) !== - 1 ) {

			this.pluginCallbacks.splice( this.pluginCallbacks.indexOf( callback ), 1 );

		}

		return this;

	}
Unregisters a plugin callback.

@param {Function} callback - The callback function to unregister.
@return {GLTFExporter} A reference to this exporter.