The Sierpinski Carpet

//---------------------------------------------------------------------------

#include <vcl.h>
#pragma hdrstop
#include <math.h>

#include "Unit1.h"
//---------------------------------------------------------------------------
#pragma package(smart_init)
#pragma resource "*.dfm"
TForm1 *Form1;
//---------------------------------------------------------------------------
__fastcall TForm1::TForm1(TComponent* Owner)
        : TForm(Owner)
{
}
//---------------------------------------------------------------------------

void Serp(double x0, double y0,double x1, double y1,double n)
{



    if(n>0)
    {
        Form1->Image1->Canvas->Brush->Color = clPurple;
        Form1->Image1->Canvas->FillRect(Rect(x0 +   (x1-x0)/3, y0 + (y1-y0)/3, x0 + 2*(x1-x0)/3, y0+2*(y1-y0)/3 ));

        Form1->Image1->Canvas->Brush->Color = clWhite;

        Serp(x0              , y0                    , x0 +   (x1-x0)/3, y0+ (y1-y0)/3,  n-1 );
        Serp(x0 +   (x1-x0)/3, y0                    , x0 + 2*(x1-x0)/3, y0+ (y1-y0)/3,  n-1 );
        Serp(x0 + 2*(x1-x0)/3, y0                    , x0 + 3*(x1-x0)/3, y0+ (y1-y0)/3,  n-1 );

        Serp(x0              , y0 + (y1-y0)/3        , x0 + (x1-x0)/3  , y0+2*(y1-y0)/3, n-1 );
        Serp(x0 +2*(x1-x0)/3 , y0 + (y1-y0)/3        , x0 + 3*(x1-x0)/3, y0+2*(y1-y0)/3, n-1 );

        Serp(x0              , y0+2*(y1-y0)/3        , x0 +   (x1-x0)/3, y0+ 3*(y1-y0)/3, n-1 );
        Serp(x0 +   (x1-x0)/3, y0+2*(y1-y0)/3        , x0 + 2*(x1-x0)/3, y0+ 3*(y1-y0)/3, n-1 );
        Serp(x0 + 2*(x1-x0)/3, y0+2*(y1-y0)/3        , x0 + 3*(x1-x0)/3, y0+ 3*(y1-y0)/3, n-1 );
  }

}



void __fastcall TForm1::Button1Click(TObject *Sender)
{
      double n=0;

      n=StrToFloat(Edit1->Text);

      double x0=0,y0=0,
             x1=550,y1=550;


     Form1->Image1->Canvas->Rectangle(x0,y0,x1,y1);
     Serp(x0,y0,x1,y1,n);


}
//---------------------------------------------------------------------------