Function circle

d3-3.2.8/d3.js:3646–3658

()

  d3.geo.circle = function() {
    var origin = [ 0, 0 ], angle, precision = 6, interpolate;
    function circle() {
      var center = typeof origin === "function" ? origin.apply(this, arguments) : origin, rotate = d3_geo_rotation(-center[0] * d3_radians, -center[1] * d3_radians, 0).invert, ring = [];
      interpolate(null, null, 1, {
        point: function(x, y) {
          ring.push(x = rotate(x, y));
          x[0] *= d3_degrees, x[1] *= d3_degrees;
        }
      });
      return {
        type: "Polygon",
        coordinates: [ ring ]
      };
    }
    circle.origin = function(x) {
      if (!arguments.length) return origin;
      origin = x;