function addFace( a, b, c, materialIndex ) {

			var vertexNormals = normals !== undefined ? [ tempNormals[ a ].clone(), tempNormals[ b ].clone(), tempNormals[ c ].clone() ] : [];
			var vertexColors = colors !== undefined ? [ scope.colors[ a ].clone(), scope.colors[ b ].clone(), scope.colors[ c ].clone() ] : [];

			var face = new THREE.Face3( a, b, c, vertexNormals, vertexColors, materialIndex );

			scope.faces.push( face );

			if ( uvs !== undefined ) {

				scope.faceVertexUvs[ 0 ].push( [ tempUVs[ a ].clone(), tempUVs[ b ].clone(), tempUVs[ c ].clone() ] );

			}

			if ( uvs2 !== undefined ) {

				scope.faceVertexUvs[ 1 ].push( [ tempUVs2[ a ].clone(), tempUVs2[ b ].clone(), tempUVs2[ c ].clone() ] );

			}

		}
@author mrdoob / http://mrdoob.com/
@author kile / http://kile.stravaganza.org/
@author alteredq / http://alteredqualia.com/
@author mikael emtinger / http://gomo.se/
@author zz85 / http://www.lab4games.net/zz85/blog
@author bhouston / http://clara.io