// Reconstructed off the top of my head (not checking any literature or other code)... because I'm a pro

srecord noeq BresenhamLineDrawer(int x1, int y1, int x2, int y2) extends Meta is Iterable<Pt> {

  int mainStepX, mainStepY;

  int sideStepX, sideStepY;

  int i;

  int x, y;

  int fraction, increment, denominator;

  // denominator is also number of pixels to return (minus 1)

  *(Pt start, Pt end) {

    x1 = start.x;

    y1 = start.y;

    x2 = end.x;

    y2 = end.y;

  }

  simplyCached void init {

    x = x1; y = y1;

    if (abs(x2-x1) > abs(y2-y1)) {

      // go mainly horizontal (right or left)

      mainStepX = sideStepX = sign(x2-x1);

      sideStepY = sign(y2-y1);

      denominator = abs(x2-x1);

      increment = abs(y2-y1);

    } else {

      // go mainly vertical (up or down)

      mainStepY = sideStepY = sign(y2-y1);

      sideStepX = sign(x2-x1);

      denominator = abs(y2-y1);

      increment = abs(x2-x1);

    }

    fraction = denominator/2;

    if (scaffolding()) printVars BresenhamLineDrawer(+x1, +y1, +x2, +y2, +denominator);

  }

  Pt next() {

    init();

    if (i > denominator) null;

    Pt p = pt(x, y);

    if (i++ < denominator) {

      fraction += increment;

      if (fraction >= denominator) {

        fraction -= denominator;

        x += sideStepX;

        y += sideStepY;

      } else {

        x += mainStepX;

        y += mainStepY;

      }

      if (scaffolding())

        printVars BresenhamLineDrawer(+i, +fraction, +increment, +denominator, +x, +y, +p);

    }

    ret p;

  }

  public ItIt<Pt> iterator() { ret iff_null(-> next()); }

  public PtBuffer points() { ret new PtBuffer(iterator()); }

}