title: How can I add a marker to a donut chart created with Raphael.js?
body: <p>I need help adding a marker to this donut chart script I've modified utilizing raphael.js. I've got most everything ready to go except for a way to dynamically generate a triangular marker. </p>
  
  <p>JSFiddle: <a href="http://jsfiddle.net/aP7MK/73/" rel="nofollow noreferrer">http://jsfiddle.net/aP7MK/73/</a></p>
  
  <pre><code>function donutChart(total, goal, avg){
  
      var paper = Raphael("canvas", 400, 400);
      paper.customAttributes.arc = function (xloc, yloc, value, total, R) {
          var alpha = 360 / total * value,
              a = (90 - alpha) * Math.PI / 180,
              x = xloc + R * Math.cos(a),
              y = yloc - R * Math.sin(a),
              path;
          if (total == value) {
              path = [
                  ["M", xloc, yloc - R],
                  ["A", R, R, 0, 1, 1, xloc - 0.01, yloc - R]
              ];
          } else {
              path = [
                  ["M", xloc, yloc - R],
                  ["A", R, R, 0, +(alpha &gt; 180), 1, x, y]
              ];
          }
          return {
              path: path
          };
      };
  
      var backCircle = paper.circle(100, 100, 40).attr({
          "stroke": "#7BC2E5",
              "stroke-width": 14
      });
  
      var theArc = paper.path().attr({
          "stroke": "#f5f5f5",
              "stroke-width": 14,
          arc: [100, 100, 0, 100, 40]
      });
  
  
      //event fired on each animation frame
      eve.on("raphael.anim.frame.*", onAnimate);
  
      //text in the middle
      theText = paper.text(100, 100, "0%").attr({
          "font-size": 18,
              "fill": "#f5f5f5",
              "font-weight": "bold"
      });
  
      //the animated arc
      theArc.rotate(0, 100, 100).animate({
          arc: [100, 100, ((total/goal) * 100), 100, 40]
      }, 1900);
  
  
      //on each animation frame we change the text in the middle
  
      function onAnimate() {
          var howMuch = theArc.attr("arc");
          theText.attr("text", Math.floor(howMuch[2]) + "%");
      }
  }
  
  donutChart(80, 140, 40);
  </code></pre>
  
  <p>Here's what I'm eventually trying to create:</p>
  
  <p><img src="https://i.stack.imgur.com/m8KTh.gif" alt=""></p>
  
  <p>I'm not worried about the styling, just need help with the marker element, which will denote where the avg argument being passed to the donutChart function lies within the chart.</p>