pythagoras.psvg

<!-- pythagoras.psvg                 -->
<!-- draws a pythagoras fractal tree -->
<!-- inspired by https://en.wikipedia.org/wiki/Pythagoras_tree_(fractal)#/media/File:Pythagoras_Tree_Colored.png -->
<psvg width="640" height="480">
  <var depth="12"/>

  <defs>
    <for i="0" true="{i<depth}" step="1">
      <var t="{i/(depth-1)}"/>
      <var dark="rgb({FLOOR(LERP(110,0,t))},{FLOOR(LERP(50,120,t))},{FLOOR(LERP(0,200,t))})"/>
      <linearGradient id="grad{i}">
        <stop offset="0%"   stop-color="{dark}"/>
        <stop offset="50%"  stop-color="rgb(200,{FLOOR(LERP(100,255,t))},0)"/>
        <stop offset="100%" stop-color="{dark}"/>
      </linearGradient>
    </for>
  </defs>

  <def-pythtree w="" d="{depth}">
    <push>
      <fill color="url(#grad{depth-d})"/>
      <path d="M0 {w/2} L{w/2} 0 L{w/2} {-w} L{-w/2} {-w} L{-w/2} 0 z"/>
    </push>

    <if true="{d==0}">
      <return/>
    </if>
    <push>
      <translate x="{-w/4}" y="{-w-w/4}"/>
      <rotate deg="-45"/>
      <pythtree w="{w/SQRT(2)}" d="{d-1}"/>
    </push>
    <push>
      <translate x="{w/4}" y="{-w-w/4}"/>
      <rotate deg="45"/>
      <pythtree w="{w/SQRT(2)}" d="{d-1}"/>
    </push>
  </def-pythtree>

  <translate x="{WIDTH/2}" y="{HEIGHT}"/>
  <pythtree w="100"/>
</psvg>