code: package org.sunflow.core.bucket;
  
  import org.sunflow.core.BucketOrder;
  
  public class RowBucketOrder implements BucketOrder {
      public int[] getBucketSequence(int nbw, int nbh) {
          int[] coords = new int[2 * nbw * nbh];
          for (int i = 0; i < nbw * nbh; i++) {
              int by = i / nbw;
              int bx = i % nbw;
              if ((by & 1) == 1)
                  bx = nbw - 1 - bx;
              coords[2 * i + 0] = bx;
              coords[2 * i + 1] = by;
          }
          return coords;
      }
  }