Uses
    GraphABC;

const
    steps = 40;

var
    start, stop: Point;
    i, x, y: integer;

begin
    start := new Point(0, WindowHeight);
    stop := new Point(WindowWidth, 0);
    Brush.Color := clWhite;
    Pen.Color := clBlack;
   
    for i := 1 to steps do
    begin
        x := round(start.X + i * (stop.X - start.X) / steps);
        y := round(start.Y + i * (stop.Y - start.Y) / steps);
        Circle(x, y, 10);
        sleep(50);
        ClearWindow();
    end;
   
end.