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<?php
        $i = 4;
        
        $image = imagecreatetruecolor(600, 200);
        imagefilledrectangle($image, 0, 0, imagesx($image) - 1, imagesy($image) - 1,
                imagecolorresolve($image, 255, 255, 255));
        $color = imagecolorresolve($image, 0, 0, 0);
 
        drawKoch($image, 0, imagesy($image) - 1, imagesx($image), imagesy($image) - 1, $i, $color);
        
        /**
         * Draws koch curve between two points.
         * @return void
         */
        function drawKoch($image, $xa, $ya, $xe, $ye, $i, $color) {
            if($i == 0)
                imageline($image, $xa, $ya, $xe, $ye, $color);
            else {
                //       C
                //      / \
                // A---B   D---E
                
                $xb = $xa + ($xe - $xa) * 1/3;
                $yb = $ya + ($ye - $ya) * 1/3;

                $xd = $xa + ($xe - $xa) * 2/3;
                $yd = $ya + ($ye - $ya) * 2/3;

                $cos60 = 0.5;
                $sin60 = -0.866;
                $xc = $xb + ($xd - $xb) * $cos60 - $sin60 * ($yd - $yb);
                $yc = $yb + ($xd - $xb) * $sin60 + $cos60 * ($yd - $yb);

                drawKoch($image, $xa, $ya, $xb, $yb, $i - 1, $color);
                drawKoch($image, $xb, $yb, $xc, $yc, $i - 1, $color);
                drawKoch($image, $xc, $yc, $xd, $yd, $i - 1, $color);
                drawKoch($image, $xd, $yd, $xe, $ye, $i - 1, $color);
            }
        }
 
        header('Content-type: image/png');
        imagepng($image);
        imagedestroy($image);
?>

uses crt, graph;
var
a,b,i:integer;

procedure drawline(ax,ay,fx,fy,i: integer);
var
bx,by,cx,cy,dx,dy,ex,ey:integer;
begin
if (i=0) or keypressed then
   line(ax,ay,fx,fy)
else
    begin
    bx:=(2*ax+fx) div 3;
    by:=(2*ay+fy) div 3;
    cx:=bx+by-ay;
    cy:=by+ax-bx;
    ex:=2*bx-ax;
    ey:=2*by-ay;
    if ax = fx then
       begin
       dx:=cx;
       dy:=ey;
       end
    else
        begin
        dx:=ex;
        dy:=cy;
        end;
    drawline(ax,ay,bx,by,i-1);
    drawline(bx,by,cx,cy,i-1);
    drawline(cx,cy,dx,dy,i-1);
    drawline(dx,dy,ex,ey,i-1);
    drawline(ex,ey,fx,fy,i-1);
    end;
end;

begin
i:=6;
a:=detect;
initgraph(a,b,'');
setbkcolor(15);
setcolor(red);
cleardevice;
outtextxy(0,0,'Wait...');
drawline(0,getmaxy, getmaxx, getmaxy, i);
outtextxy(0,20,'Sucsessful! Press any key...');
if keypressed then readkey;
readkey;
closegraph;
end.