An excerpt from Jon Corbett's portrait beading code

generations.vlw

For(int x = 1; x <= NumberOfRows; x++){
switch(x % 2){
    case 0:
       For(currentColumn = NumberOfColumns; currentColumn > 0; currentColumn--){
         placeBeadAt(x, currentColumn);
       }
       break;
    default:
       For(currentColumn = 1; currentColumn <= NumberOfColumns; currentColumn++){
         placeBeadAt(x, currentColumn);
       }
       break;
  }
 }