!function(){

	var gradPie={};



	var pie = d3.layout.pie().sort(null).value(function(d) {return d.value;});



	createGradients = function(defs, colors, r){

		var gradient = defs.selectAll('.gradient')

			.data(colors).enter().append("radialGradient")

			.attr("id", function(d,i){return "gradient" + i;})

			.attr("gradientUnits", "userSpaceOnUse")

			.attr("cx", "0").attr("cy", "0").attr("r", r).attr("spreadMethod", "pad");



		gradient.append("stop").attr("offset", "0%").attr("stop-color", function(d){ return d;});



		gradient.append("stop").attr("offset", "30%")

			.attr("stop-color",function(d){ return d;})

			.attr("stop-opacity", 1);



		gradient.append("stop").attr("offset", "70%")

			.attr("stop-color",function(d){ return "black";})

			.attr("stop-opacity", 1);

	};



	gradPie.draw = function(id, data, cx, cy, r){

		var gPie = d3.select("#"+id).append("g")

			.attr("transform", "translate(" + cx + "," + cy + ")");



		createGradients(gPie.append("defs"), data.map(function(d){ return d.color; }), 2.5*r);



		gPie.selectAll("path").data(pie(data))

			.enter().append("path").attr("fill", function(d,i){ return "url(#gradient"+ i+")";})

			.attr("d", d3.svg.arc().outerRadius(r))

			.each(function(d) { this._current = d; });

	};



	gradPie.transition = function(id, data, r) {

		function arcTween(a) {

			var i = d3.interpolate(this._current, a);

			this._current = i(0);

			return function(t) { return d3.svg.arc().outerRadius(r)(i(t));  };

		}



		d3.select("#"+id).selectAll("path").data(pie(data))

			.transition().duration(750).attrTween("d", arcTween);

	};



	this.gradPie = gradPie;

}();