Рисование эллипса

uses GraphABC;
 
procedure RLine(x, y, x2, y2: real):=Line(Round(x), Round(y), Round(x2), Round(y2));
 
procedure Draw(cx, cy, r: integer; hK, vK: real);
var
  x, y, xF, yF: integer;
  MoveDown, MoveRightDown, MoveRight: integer;
  procedure DrawPoints(x1, y1, x2, y2: integer);
  begin
    RLine(cx + xF * hK, cy + yF * vK, cx + x * hK, cy + y * vK);
    RLine(cx + xF * hK, cy - yF * vK, cx + x * hK, cy - y * vK);
    RLine(cx - xF * hK, cy + yF * vK, cx - x * hK, cy + y * vK);
    RLine(cx - xF * hK, cy - yF * vK, cx - x * hK, cy - y * vK);
  end;
 
begin
  x := 0;
  y := r;
  while ((y >= 0) or (x < r)) do
  begin
    Sleep(15);
    xF := x;
    yF := y;
    MoveDown := Abs(Sqr(r) - Sqr(x) - Sqr(y - 1));
    MoveRight := Abs(Sqr(r) - Sqr(x + 1) - Sqr(y));
    MoveRightDown := Abs(Sqr(r) - Sqr(x + 1) - Sqr(y - 1));
    if MoveDown < MoveRight then
    begin
      Dec(y);
      if MoveRightDown < MoveDown then Inc(x);
    end
    else
    begin
      Inc(x);
      if MoveRightDown < MoveRight then Dec(y);
    end;
    DrawPoints(xF, yF, x, y);
  end;
end;
 
procedure DrawEllipse(x, y, x1, y1: integer);
begin
  var dx := Abs(x1 - x) / 2;
  var dy := Abs(y1 - y) / 2;
  var r := Min(dx, dy);
  var hK := dx / r;
  var vK := dy / r;
  Draw(Round(x + dx), Round(y + dy), Round(r), hK, vK);
end;
 
begin
  DrawEllipse(100, 100, 600, 600);
end.

DrawEllipse(100, 100, 200, 100);