Animating pie chart slices in Raphaeljs

animatedPie.js

var r = Raphael("holder");
r.customAttributes.segment = function (x, y, r, a1, a2) {
    var flag = (a2 - a1) > 180,
        clr = (a2 - a1) / 360;
    a1 = (a1 % 360) * Math.PI / 180;
    a2 = (a2 % 360) * Math.PI / 180;
    return {
        path: [["M", x, y], ["l", r * Math.cos(a1), r * Math.sin(a1)], ["A", r, r, 0, +flag, 1, x + r * Math.cos(a2), y + r * Math.sin(a2)], ["z"]],
        fill: "hsb(" + clr + ", .75, .8)"
    };
};

points = [10, 20, 15];
total = 45;
start = 0;
paths = [];
for(i=0; i<=2; i++) {
  size = 360 / total * points[i];
  var slice = r.path();
  slice.attr({segment: [250, 250, 200, start, start + size], stroke: "#000", title: "Slice "+i});
  paths.push(slice);
  start += size;
}

newPoints = [5, 20, 20];
start = 0;
for(i=0; i<=2; i++) {
  size = 360 / total * newPoints[i];
  paths[i].animate({segment: [250, 250, 200, start, start + size]}, 800);
  paths[i].angle = start - size / 2;
  start += size;
}