uses graph, crt;
type punkt=record
     x, y: real;
    end;
type nelinurk=array[1..4]of punkt;

procedure loo_nelinurk(x1, y1, x2, y2, x3, y3, x4, y4: real;
                       var nn: nelinurk);
begin
  nn[1].x:=x1; nn[1].y:=y1;
  nn[2].x:=x2; nn[2].y:=y2;
  nn[3].x:=x3; nn[3].y:=y3;
  nn[4].x:=x4; nn[4].y:=y4;
end;

procedure keera_nelinurk(nurk: real; var nn: nelinurk);
 var i: integer;
 abi:real;
begin
 for i:=1 to 4 do
 begin
   abi:=nn[i].x;
   nn[i].x:=nn[i].x*cos(nurk)-nn[i].y*sin(nurk);
   nn[i].y:=abi*sin(nurk)+nn[i].y*cos(nurk);
 end;
end;

procedure joonista_nelinurk(nn: nelinurk; x, y: integer);
 var i: integer;
begin
 for i:=1 to 3 do
     line(x+round(nn[i].x),   y+round(nn[i].y),
          x+round(nn[i+1].x), y+round(nn[i+1].y));
 line(x+round(nn[4].x), y+round(nn[4].y),
      x+round(nn[1].x), y+round(nn[1].y));
end;

procedure joonista_keeratud_nelinurk(nn: nelinurk; x, y: integer; nurk: real);
 var abinelinurk: nelinurk;
begin
 abinelinurk:=nn;
 keera_nelinurk(nurk, abinelinurk);
 joonista_nelinurk(abinelinurk, x, y);
end;

var nurk, raadius: real;
d, m, keskx, kesky: integer;
nn1: nelinurk;
begin
 d:=detect; initgraph(d, m, '');
 nurk:=0; keskx:=300; kesky:=100; raadius:=50;
 loo_nelinurk(-10, -5, 10, -5, 10, 5, -10, 5,nn1);

 repeat
  cleardevice;
  joonista_keeratud_nelinurk(nn1, 100,100, nurk);
  delay(25);
  nurk:=nurk+0.4;
 until keypressed;
 readkey;
 repeat
  cleardevice;
      joonista_keeratud_nelinurk(nn1, round(keskx+raadius*sin(nurk)),
          round(kesky+raadius*cos(nurk)), 3*nurk);
  delay(25);
  nurk:=nurk+0.1;
 until keypressed;
 closegraph;
end.