@thi.ng/grid-iterators/zigzag-diagonal.js

2D grid and shape iterators w/ multiple orderings

import { __opts } from "./utils.js";
function* zigzagDiagonal2d(opts) {
  const { cols, rows, tx } = __opts(opts);
  const num = cols * rows - 1;
  for (let x = 0, y = 0, ny = 0, dx = -1, dy = 1, d = 0, down = true, i = 0; i <= num; i++) {
    yield tx(x, y);
    if (i !== num) {
      do {
        if (y === ny) {
          if (down) {
            y++;
            d++;
            ny = 0;
          } else {
            x++;
            ny = ++d;
          }
          down = !down;
          dx *= -1;
          dy *= -1;
        } else {
          x += dx;
          y += dy;
        }
      } while (x >= cols || y >= rows);
    }
  }
}
export {
  zigzagDiagonal2d
};