koch.psvg

<!-- koch.psvg               -->
<!-- draws a koch snowflake  -->
<psvg width="400" height="400">
  <def-snowflake x1="" y1="" x2="" y2="" d="">
    <if true="{d==0}">
      <line x1="{x1}" y1="{y1}" x2="{x2}" y2="{y2}" />
      <return/>
    </if>
    <var x3="{(x1*2+x2)/3}"/>
    <var x4="{(x2*2+x1)/3}"/>
    <var y3="{(y1*2+y2)/3}"/>
    <var y4="{(y2*2+y1)/3}"/>
    <var dx="{(x2-x1)/3}"/>
    <var dy="{(y2-y1)/3}"/>
    <var x5="{(dx-dy*SQRT(3))/2+x3}"/>
    <var y5="{(dy+dx*SQRT(3))/2+y3}"/>
    <snowflake x1="{x1}" y1="{y1}" x2="{x3}" y2="{y3}" d="{d-1}"/>
    <snowflake x1="{x3}" y1="{y3}" x2="{x5}" y2="{y5}" d="{d-1}"/>
    <snowflake x1="{x5}" y1="{y5}" x2="{x4}" y2="{y4}" d="{d-1}"/>
    <snowflake x1="{x4}" y1="{y4}" x2="{x2}" y2="{y2}" d="{d-1}"/>
  </def-snowflake>

  <stroke color="black" cap="round"/>
  <snowflake x1="200" y1="10"  x2="50"  y2="310" d="5"/>
  <snowflake x1="350" y1="310" x2="200" y2="10"  d="5"/>
  <snowflake x1="50"  y1="310" x2="350" y2="310" d="5"/>

</psvg>