Dragon Curve 2-JS Tutorial-php.cn

Dragon Curve 2

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Release： 2024-08-08 16:30:22

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I want to show the dragon curve in five language soluitons:

Pascal
Python
Turtle
Delphi
Java Script

A dragon curve is any member of a family of self-similar fractal curves, which can be approximated by recursive methods such as Lindenmayer systems as a procedure in Pascal shows:

procedure Dragon(n,a,t:Integer; d,x,y: Double; var b: TBitmap);
  var a1, a2: integer;
begin
 if n <= 1 then begin
   with b.Canvas do begin
     Pen.Color:= random(p);
     MoveTo(Trunc(x + 0.5), Trunc(y + 0.5));
     LineTo(Trunc(x + d *_cos[a]+0.5),Trunc(y+d *_sin[a]+0.5));
     exit;
   end;
 end;
 d:= d * s;
 a1:= (a - t) and 7;
 a2:= (a + t) and 7;
 dragon(n - 1, a1, 1, d, x, y, b);
 dragon(n - 1, a2, -1, d, x + d *_cos[a1], y + d *_sin[a1], b);
end;

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Recursively a right curling dragon is a right dragon followed by a left dragon, at 90-degree angle. And a left dragon is a left followed by a right. The same you get also with Python and Turtle in maXbox:

Const DRAGFUNC =
  'def dragon(level=4, size=200, direction=45):   '+LF+
  '  if level:                                     '+LF+
  '      right(direction)                          '+LF+
  '      dragon(level-1, size/1.41421356237, 45)   '+LF+
  '      left(direction * 2)                       '+LF+
  '      dragon(level-1, size/1.41421356237, -45)  '+LF+
  '      right(direction)                          '+LF+
  '  else:                                         '+LF+
  '      forward(size)                             ';

function PyCodeDragonTurtle(imgpath, aAPIKey: string): string;
begin
  with TPythonEngine.Create(Nil) do begin
  //pythonhome:= 'C:\Users\User\AppData\Local\Programs\Python\Python312\';
  try
    loadDLL;
    autofinalize:= false;
    ExecString('from turtle import right,left,forward,speed, exitonclick,hideturtle');
    ExecStr(DRAGFUNC); 
    ExecStr('speed(0)');  
    //ExecStr('hideturtle()'); 
    ExecStr('dragon(6)');
    ExecStr('exitonclick()');
    //result:= (EvalStr('r.json()')); *)
  except
    raiseError;        
  finally      
    Free;
  end; 
 end;
end;

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The dragon curve is probably most commonly thought of as the shape that is generated from repeatedly folding a strip of paper in half.

Dragon Curve 2
Dragon as Pen.Color:= (p);

The script you get at:
Multilanguage Script

https://sourceforge.net/projects/maxbox/files/Examples/13_General/1320_dragon_curve_51_py.txt/download

Dragon Curve 2
with Depth = 9

Dragon Curve 2

Dragon Curve 2
Pen.Width:= 2; Pen.Color := cllime;

Turtle Sound

Dragon Curve 2
Try the sound that turtle with angle as amplitude and step as tone:

procedure DrawDragon2(step, adir: integer; len:real);
begin
  //myturtle:= TJvTurtle.create(self);
  with myturtle do begin
    if (step >-1) and (len >1) then begin
      len:= len /sqrt(2);
      Turn(45*adir);
        DrawDragon2(step-1, +1, len);
      Turn(-90*adir);
        DrawDragon2(step-1, -1, len);
      Turn(45*adir);
    end else      //*)
      moveforward(len )
  end;  
end;

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Dragon Curve 2

JavaScript Embedded

The Microsoft Edge WebView2 control allows you to embed web technologies (HTML, CSS, and JavaScript) in your native apps. The WebView2 control uses Microsoft Edge as the rendering engine to display the web content in native apps.

Dragon Curve 2

<!-- DragonCurve.html -->
<html>
<head>
<script type='text/javascript'>
function pDragon(cId) {
  // Plotting Dragon curves. 2/25/17 aev
  var n=document.getElementById('ord').value;
  var sc=document.getElementById('sci').value;
  var hsh=document.getElementById('hshi').value;
  var vsh=document.getElementById('vshi').value;
  var clr=document.getElementById('cli').value;
  var c=c1=c2=c2x=c2y=x=y=0, d=1, n=1<<n;
  var cvs=document.getElementById(cId);
  var ctx=cvs.getContext("2d");
  hsh=Number(hsh); vsh=Number(vsh);
  x=y=cvs.width/2;
  // Cleaning canvas, init plotting
  ctx.fillStyle="white"; ctx.fillRect(0,0,cvs.width,cvs.height);
  ctx.beginPath();
  for(i=0; i<=n;) {
    ctx.lineTo((x+hsh)*sc,(y+vsh)*sc);
    c1=c&1; c2=c&2;
    c2x=1*d; if(c2>0) {c2x=(-1)*d}; c2y=(-1)*c2x;
    if(c1>0) {y+=c2y} else {x+=c2x}
    i++; c+=i/(i&-i);
  }
  ctx.strokeStyle = clr;  ctx.stroke();
}
</script>
</head>
<body>
<p><b>Please input order, scale, x-shift, y-shift, color:</></p>
<input id=ord value=11 type="number" min="7" max="25" size="2">
<input id=sci value=7.0 type="number" min="0.001" max="10" size="5">
<input id=hshi value=-265 type="number" min="-50000" max="50000" size="6">
<input id=vshi value=-260 type="number" min="-50000" max="50000" size="6">
<input id=cli value="red" type="text" size="14">
<button onclick="pDragon('canvId')">Plot it!</button>
<h3>Dragon curve</h3>
<canvas id="canvId" width=640 height=640 style="border: 2px inset;"></canvas>
</body>
</html>

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Dragon Curve 2
Modify and explore in EdgeView of maXbox5
The Script you find at: