Снежинка Коха

program primer_8;
{$S+}
Uses graph,crt;
label 1,2;
var x,y,a,b,p,n:integer;
t,l:real;
g:char;
procedure snow(x,y,k:integer;l:real);
var x1,y1:integer;
i:integer;
begin
if k=0 then exit;
for i:=1 to p do
begin
x1:=trunc(x+l*cos(2*pi*(i-1)/p));
y1:=trunc(y+l*sin(2*pi*(i-1)/p));
if (x1>640) or (y1>480) or (x1<0) or (y1<0) then begin
outtextxy(10,10,'Sorry, picture not on the screen !!!');
outtextxy(10,20,'Press any key for exit');
end;
if keypressed then halt;
line(x,y,x1,y1);
snow(x1,y1,k-1,l*t);
end;
end;
begin
x:=320;
y:=240;
g:='y';
write('Demo ? [Y/N] - '); readln(g);
if g='y'
  then
     begin  n:=3; p:=6; l:=100; t:=0.25; goto 1; end;
write('n='); readln(n);
if (n<=0) or (n>20)
   then
      begin write('No!');readln;goto 2; end;
write('p='); readln(p);
if (p<=0) or (p>50)
  then
    begin write('No!');readln;goto 2; end;
write('l= ');readln(l);
if (l<=0) or (l>250)
  then
    begin write('No!');readln;goto 2; end;
write('t='); readln(t);
1:a:=detect; b:=detect;
initgraph(a,b,'c:\lg\bgi');
snow(x,y,n,l);
readkey;
closegraph;
2:end.