// Generated by CoffeeScript 1.4.0

/* compute a Lindenmayer system given an axiom, a number of steps and rules
*/


(function() {
  var fractalize, svg_path, transition, tweenDash;

  fractalize = function(config) {
    var char, i, input, output, _i, _j, _len, _ref;
    input = config.axiom;
    for (i = _i = 0, _ref = config.steps; 0 <= _ref ? _i < _ref : _i > _ref; i = 0 <= _ref ? ++_i : --_i) {
      output = '';
      for (_j = 0, _len = input.length; _j < _len; _j++) {
        char = input[_j];
        if (char in config.rules) {
          output += config.rules[char];
        } else {
          output += char;
        }
      }
      input = output;
    }
    return output;
  };

  /* convert a Lindenmayer string into an SVG path string
  */


  svg_path = function(config) {
    var angle, char, path, _i, _len, _ref;
    angle = 0.0;
    path = 'M0 0';
    _ref = config.fractal;
    for (_i = 0, _len = _ref.length; _i < _len; _i++) {
      char = _ref[_i];
      if (char === '+') {
        angle += config.angle;
      } else if (char === '-') {
        angle -= config.angle;
      } else if (char === 'F') {
        path += "l" + (config.side * Math.cos(angle)) + " " + (config.side * Math.sin(angle));
      }
    }
    return path;
  };

  window.main = function() {
    var d, gosper, height, svg, width;
    gosper = fractalize({
      axiom: 'A',
      steps: 4,
      rules: {
        A: 'A-FB--FB-F++AF++A-F+AF+B-',
        B: '+A-FB-F+B--FB--F+AF++AF+B'
      }
    });
    d = svg_path({
      fractal: gosper,
      side: 8,
      angle: Math.PI / 3
    });
    width = 960;
    height = 500;
    svg = d3.select('body').append('svg').attr('width', width).attr('height', height);
    svg.append('path').attr('class', 'curve shadow').attr('d', d).attr('transform', 'translate(680,300)');
    return svg.append('path').attr('class', 'curve').attr('d', d).attr('transform', 'translate(680,300)').call(transition);
  };

  /* animate the path
  */


  /* from Mike Bostock's stroke dash interpolation example http://bl.ocks.org/mbostock/5649592
  */


  tweenDash = function() {
    var i, l;
    l = this.getTotalLength();
    i = d3.interpolateString('0,' + l, l + ',' + l);
    return function(t) {
      return i(t);
    };
  };

  transition = function(path) {
    return path.transition().duration(20000).attrTween('stroke-dasharray', tweenDash);
  };

}).call(this);