Кривая Дракона

uses SmallTurtle;
const
  Angle = 90;
  StringWay = '1101100111001001110110001100100111001100111001000110110001100100';
  n = 20;
  
var
  t: Turtle;
  
procedure Draw(s: string);
begin
  for var i := 1 to s.Length do
  begin
    t.MoveForward();
    case s.Chars[i] of
      '1': t.Rotate(Angle);
      '0': t.Rotate(-Angle);
    end;
  end;
end;
 
procedure DrawCurve();
begin
  for var i := 0 to n - 1 do
    Draw(StringWay);
end;
 
begin
  t := new Turtle();
  t.Step := 5;
  DrawCurve();
end.

unit SmallTurtle;
 
uses GraphABC;
const
  Red = clRed;
  Yellow = clYellow;
  Orange = clOrange;
  Green = clGreen;
  Cyan = clCyan;
  Blue = clBlue;
  Purple = clPurple;
  Black = clBlack;
  White = clWhite;
  Gray = clGray;
 
type
  ///Turtle's class
  Turtle = class
  private 
    PenColorP: Color;
    PenWidthP: integer;
    StepP: integer;
    AngleP: real;
    IsPenDownP: boolean;
    x, y: integer;
    procedure RLine(x, y, x1, y1: real) := Line(Round(x), Round(y), Round(x1), Round(y1));
  public 
    property PenColor: Color read PenColorP write PenColorP;
    property PenWidth: integer read PenWidthP write PenWidthP;
    property Angle: real read AngleP write AngleP;
    property Step: integer read StepP write StepP;
    property IsPenDown: boolean read IsPenDownP write IsPenDownP;
    
    ///Reset coordinates and angle to default.
    procedure Reset();
    begin
      x := Window.Width div 2;
      y := Window.Height div 2;
      Angle := -90;
    end;
    
    constructor ();begin Reset();Step := 1;IsPenDown := true;Angle := -90;PenWidth := 1;PenColor := clBlack; end;
    
    ///Set pen settings.
    procedure SetPenSettings();
    begin
      SetPenColor(PenColor);
      SetPenWidth(PenWidth);
    end;
    
    ///Move forward.
    procedure MoveForward();
    begin
      SetPenSettings();
      if IsPenDown then RLine(x, y, x + Step * Cos(DegToRad(Angle)), y + Step * Sin(DegToRad(Angle)));
      x := Round(x + Step * Cos(DegToRad(Angle)));
      y := Round(y + Step * Sin(DegToRad(Angle)));
    end;
    
    ///Move back.
    procedure MoveBack();
    begin
      SetPenSettings();
      if IsPenDown then RLine(x, y, x + Step * Cos(DegToRad(Angle)), y - Step * Sin(DegToRad(Angle)));
      x := Round(x + Step * Cos(DegToRad(Angle)));
      y := Round(y - Step * Sin(DegToRad(Angle)));
    end;
    
    ///Clear window.
    procedure Clear() := ClearWindow;
    
    ///Rotate turtle.
    procedure Rotate(a: real) := Angle := Angle + a;
    
    ///Rotate turtle on 180 degrees.
    procedure SwapAngle(a: real) := Angle := Angle + 180;
    
    ///Set random pen width.
    procedure SetRandomPenWidth(max: integer) := PenWidth := Random(max);
    
    ///Set random pen color.
    procedure SetRandomPenColor();
    begin
      var rnd := Random(10);
      case rnd of
        0: PenColor := Red;
        1: PenColor := Yellow;
        2: PenColor := Orange;
        3: PenColor := Green;
        4: PenColor := Cyan;
        5: PenColor := Blue;
        6: PenColor := Purple;
        7: PenColor := Black;
        8: PenColor := White;
        9: PenColor := Gray;
      end;
    end;
    
    ///Set pen color by number index.
    procedure SetColorByNumber(i: integer);
    begin
      case i of
        0: PenColor := Red;
        1: PenColor := Yellow;
        2: PenColor := Orange;
        3: PenColor := Green;
        4: PenColor := Cyan;
        5: PenColor := Blue;
        6: PenColor := Purple;
        7: PenColor := Black;
        8: PenColor := White;
        9: PenColor := Gray;
      end;
    end;
    
    ///Copy properties values from another turtle.
    procedure CopyPenSettings(t: Turtle);
    begin
      PenColor := t.PenColor;
      PenWidth := t.PenWidth;
      Angle := t.Angle;
      Step := t.Step;
      IsPenDown := t.IsPenDown;
    end;
  end;
 
initialization
  SetWindowCaption('Turtle');
end.