Arc Sentiment Canvas

forked from mbostock's block: Arc Padding III

<!DOCTYPE html>
<meta charset="utf-8">
<canvas width="960" height="500"></canvas>
<script src="//d3js.org/d3.v4.0.0-alpha.4.min.js"></script>
<script>

let positive = 35;
let neutral = 10;
let negative = 55;
  
var dataBegin = [0, 0, 0];
var dataEnd = [positive, neutral, negative];

var canvas = document.querySelector("canvas"),
    context = canvas.getContext("2d");

var width = canvas.width,
    height = canvas.height,
    radius = Math.min(width, height) / 2;

var colors = [
  "#ccc", "#009900", "#990000" 
];

var arc = d3.arc()
    .outerRadius(radius - 10)
    .innerRadius(radius - 30)
    .padAngle(0.02)
    .context(context);

var pie = d3.pie();

var arcs = pie(dataEnd);

context.translate(width / 2, height / 2);

context.globalAlpha = 0.5;
arcs.forEach(function(d, i) {
  context.beginPath();
  arc(d);
  context.fillStyle = colors[i];
  context.fill();
});

context.globalAlpha = 1;
context.beginPath();

arcs.forEach(arc);
  
context.lineWidth = 1.5;
//context.stroke();
  
function arcTween(a) {
  var i = d3.interpolate(this._current, a);
  this._current = i(0);
  return function(t) {
    return arc(i(t));
  };
}

</script>

https://d3js.org/d3.v4.0.0-alpha.4.min.js