Написать программу, которая рисует восьмиугольник, движущийся по экрану - Turbo Pascal

uses crt, graph;
 
const
  N     = 8;
  side  = 40;
  dFi   = pi / 180;
  FiLim = 2 * pi / N;
  sideColor = 3;
  pause = 20;
 
type
  top = record
    x, y: integer;
  end;
 
var
  tops: array[1..N] of top;
  FiCur: real;
  i, lineY, lineX: integer;
  graph_device, graph_mode: integer;
 
procedure shift;
var
  bufTop: top;
  i: integer;
begin
  bufTop.x := tops[N].x;
  bufTop.y := tops[N].y;
  for i := 1 to N - 1 do
  begin
    tops[i + 1].x := tops[i].x;
    tops[i + 1].y := tops[i].y;
  end;
  tops[1].x := bufTop.x;
  tops[1].y := bufTop.y;
end;
 
procedure paint(color: word);
var
  i: integer;
begin
  setcolor(color);
  if color = sideColor then line(0, lineY, lineX, lineY);
  for i := 1 to N do
    if i <> N then line(tops[i].x, tops[i].y, tops[i + 1].x, tops[i + 1].y)
              else line(tops[N].x, tops[N].y, tops[1].x,     tops[1].y);
end;
 
procedure recount;
var
  i: integer;
begin
  tops[1].x := round(tops[N].x + side * cos(FiCur));
  tops[1].y := round(tops[N].y - side * sin(FiCur));
  for i := 2 to N - 1 do
  begin
    tops[i].x := round(tops[i - 1].x + side * cos(FiCur + (i - 1) * FiLim));
    tops[i].y := round(tops[i - 1].y - side * sin(FiCur + (i - 1) * FiLim));
  end;
end;
 
procedure rotate;
begin
  delay(pause);
  paint(black);
  FiCur := FiCur - dFi;
  recount;
  paint(sideColor);
end;
 
begin
  FiCur := FiLim;
  graph_device := detect;
  InitGraph(graph_device, graph_mode, '');
  lineX := GetMaxX;
  lineY := GetMaxY * 3 div 4;
  tops[N].x := 150;
  tops[N].y := lineY;
  recount;
  for i := 1 to N do
  begin
    repeat rotate until FiCur <= 0;
    paint(black);
    FiCur := FiLim;
    shift;
  end;
  closegraph;
end.