getDirectives( shaderStage ) {

		const snippets = [];
		const directives = this.directives[ shaderStage ];

		if ( directives !== undefined ) {

			for ( const directive of directives ) {

				snippets.push( `enable ${directive};` );

			}

		}

		return snippets.join( '\n' );

	}
Returns the directives of the given shader stage as a WGSL string.

@param {string} shaderStage - The shader stage.
@return {string} A WGSL snippet that enables the directives of the given stage.