processBuffer( buffer ) {

		const json = this.json;
		const buffers = this.buffers;

		if ( ! json.buffers ) json.buffers = [ { byteLength: 0 } ];

		// All buffers are merged before export.
		buffers.push( buffer );

		return 0;

	}
Process a buffer to append to the default one.
@param {ArrayBuffer} buffer
@return {0}