-------------------------------------------------------------------------------
-- Autor: AdaLogoTeam
-- Datum: 2005-08-16
-- Idee:  Zeichnen von Sierpinski-Teppich 	
-------------------------------------------------------------------------------

with adalogo;
use adalogo;

procedure sierpinski is

  a_x : integer := 0;
  a_y : integer := 0;
  
  b_x : integer;
  b_y : integer;
  
  axy : integer := 1;
  
  lengthf :integer := 8; -- schrittlaenge startwert
  direction : integer := 90; -- richtung in grad
  rotation : integer := 90; -- drehung in grad
  
  procedure teppich(instruction : integer; depth : integer) is 
  
    p : integer := 0;
    q : integer := 0;
  
  begin 
    if depth = 0 then
      null;
    else 
      depth := depth - 1;
    
      -- F
      -- F -> F+F-F-FF-F-F-MF := 0
      -- M -> MMM := 1
      -- + := 3
      -- - := 4
      if instruction = 0 or instruction = 1 then
      
        if instruction = 0 then
          teppich(0,depth); -- F
          teppich(3,depth); -- +
          teppich(0,depth); -- F
          teppich(4,depth); -- -
          teppich(0,depth); -- F
          teppich(4,depth); -- -
          teppich(0,depth); -- F
          teppich(0,depth); -- F
          teppich(4,depth); -- -
          teppich(0,depth); -- F
          teppich(4,depth); -- -
          teppich(0,depth); -- F
          teppich(4,depth); -- -
          teppich(1,depth); -- M
          teppich(0,depth); -- F
        elsif instruction = 1 then
          teppich(1,depth); -- M
          teppich(1,depth); -- M
          teppich(1,depth); -- M
        else
          put_line("This should never happen.");
        end if;
      
        if depth = 0 then
          if direction = 0 then
            p := lengthf;
            q := 0;
          elsif direction = 90 then
            p := 0;
            q := lengthf;
          elsif direction = 180 then
            p := -lengthf;
            q := 0;
          elsif direction = 270 then
            p := 0;
            q := -lengthf;
          else
            put_line("This should never happen!");
          end if;
          
          b_x := a_x + p;
          b_y := a_y + q;
          
          move_to(b_x,b_y);
          
          a_x := b_x;
          a_y := b_y;
          
        end if;
        
      elsif instruction = 3 then
        direction := (direction + rotation) mod 360;
        
      elsif instruction = 4 then
        direction := (direction - rotation) mod 360;
        
      else
        put_line("This should never happen!");
      end if;
    end if;
  end;

begin
  turtle_reset;
  teppich(0,5);
end;