Function d3_geo_areaRingStart

explainshell/web/static/js/d3.v3.js:2091–2109

()

    }
  };
  function d3_geo_areaRingStart() {
    var λ00, φ00, λ0, cosφ0, sinφ0;
    d3_geo_area.point = function(λ, φ) {
      d3_geo_area.point = nextPoint;
      λ0 = (λ00 = λ) * d3_radians, cosφ0 = Math.cos(φ = (φ00 = φ) * d3_radians / 2 + π / 4), 
      sinφ0 = Math.sin(φ);
    };
    function nextPoint(λ, φ) {
      λ *= d3_radians;
      φ = φ * d3_radians / 2 + π / 4;
      var dλ = λ - λ0, cosφ = Math.cos(φ), sinφ = Math.sin(φ), k = sinφ0 * sinφ, u0 = d3_geo_areaRingU, v0 = d3_geo_areaRingV, u = cosφ0 * cosφ + k * Math.cos(dλ), v = k * Math.sin(dλ);
      d3_geo_areaRingU = u0 * u - v0 * v;
      d3_geo_areaRingV = v0 * u + u0 * v;
      λ0 = λ, cosφ0 = cosφ, sinφ0 = sinφ;
    }
    d3_geo_area.lineEnd = function() {
      nextPoint(λ00, φ00);
    };
  }
  d3.geo.bounds = d3_geo_bounds(d3_identity);
  function d3_geo_bounds(projectStream) {
    var x0, y0, x1, y1;