Классический фрактал множества Жулиа

unit Unit1; 
 
{$mode objfpc}{$H+}
 
interface
 
uses
  Classes, SysUtils, FileUtil, Forms, Controls, Graphics, Dialogs, StdCtrls,
  ExtCtrls;
 
type
 
  { TForm1 }
 
  TForm1 = class(TForm)
    Button1: TButton;
    PaintBox1: TPaintBox;
    procedure Button1Click(Sender: TObject);
  private
    { private declarations }
  public
    { public declarations }
  end; 
 
var
  Form1: TForm1; 
 
implementation
 
{$R *.lfm}
 
{ TForm1 }
 
procedure TForm1.Button1Click(Sender: TObject);
type
	TComplex = record
		X : Real;
		Y : Real;
	end;
 
const
	iter = 50;
	max  = 16;
 
var
	z, t, c : TComplex;
	x, y, n : Integer;
	Cancel  : Boolean;
	gd, gm  : Smallint;
	mx, my  : Integer;
        col: TColor;
begin
   Randomize;
   PaintBox1.Canvas.Clear;
   Mx := PaintBox1.Canvas.Width div 2;
   My := PaintBox1.Canvas.Height div 2;
   	for y := -my to my do
		for x := -mx to mx do
		begin
			n := 0;
			z.x := x * 0.005;
			z.y := y * 0.005;
			c.x := 0.11;
			c.y := -0.66;
			while (sqr(z.x) + sqr(z.y) < max) and (n < iter) do
			begin
				t := z;
				{z^2 + c}
				z.x := sqr(t.x) - sqr(t.y) + c.x;
				z.y := 2*t.x*t.y + c.y;
				Inc(n);
   			end;
			if n < iter then begin
                          col := n*6 mod 255;
                          PaintBox1.Canvas.Pixels[mx+x,my+y]:=RGBToColor(col,0,0);
			end;
 
		end;
end;
 
end.