code: function calculateVertexCount() {
  
  		var count = ( radialSegments + 1 ) * ( heightSegments + 1 );
  
  		if ( openEnded === false ) {
  
  			count += ( ( radialSegments + 1 ) * nbCap ) + ( radialSegments * nbCap );
  
  		}
  
  		return count;
  
  	}
docs: helper functions