scope renderLineCompedSingleLevels_raw_v3.

static long[][] renderLineCompedSingleLevels_raw_v3(LineCompedSingle<Char> lc) {
  int n = lcLength(lc);
  
  // each matrix element is the character's symbol number+1 combined with its starting position (or 0 for empty)
  L<long[]> rows = new AutoCreateList<>(() -> new long[n]);
  fill(lc, rows, 0, 0, lc.main);
  ret toArray(rows, long[].class);
}
  
// returns new x
static int #fill(LineCompedSingle<Char> lc, L<long[]> rows, int x, int y, L<Int> symbols) {
  //printVars_str fill(+x, +y, +symbols);
  for (int idx : symbols) {
    if (idx < l(lc.literals)) {
      rows.get(y)[x] = twoIntsToLong(idx+1);
      x++;
    } else {
      int newX = fill(lc, rows, x, y+1, intPairToList(lc.getPair(idx)));
      while (x < newX) rows.get(y)[x++] = idx+1;
    }
  }
  ret x;
}

end scope

Began life as a copy of #1031202