readMaterialGroup( chunk ) {

		const name = chunk.readString();
		const numFaces = chunk.readWord();

		this.debugMessage( '         Name: ' + name );
		this.debugMessage( '         Faces: ' + numFaces );

		const index = [];
		for ( let i = 0; i < numFaces; ++ i ) {

			index.push( chunk.readWord( ) );

		}

		return { name: name, index: index };

	}
Read material group data chunk.

@private
@param {Chunk} chunk - Chunk in use.
@return {Object} Object with name and index of the object.