an idea

render_leaves.js

function Leaf(){
  this.type;      // 'active', 'seen', 'unseen'
  this.position;  // [300,2311,45] (x,y,degree) degree in range 0...360
  this.link;      // '/program/page/13'
  this.num;       // 4
}

var l1 = new Leaf();
l1.type = 'active';
l1.position = [200,400,45];
l1.link = '/program/page/12'
l1.num = 2;

// or....

leaf1 = {
  type: 'active', // active, seen, unseen leaves render different 
  position: [12,13,45],
  link: 'program/page/1',
  num: '3',
  function render(){
    // get the right svg leaf: active (bright green w/ level number), seen (dim green w/ level number), or unseen (dim green w/o number).
    // position it.
    // apply a link to active or seen leaves.
    // apply a number to active and seen leaves.
  }
}