@visx/vendor/vendor-cjs/d3-geo/src/centroid.js

vendored packages for visx

"use strict";

Object.defineProperty(exports, "__esModule", {
  value: true
});
exports.default = _default;
var _index = require("../../../vendor-cjs/d3-array/src/index.js");
var _math = require("./math.js");
var _noop = _interopRequireDefault(require("./noop.js"));
var _stream = _interopRequireDefault(require("./stream.js"));
function _interopRequireDefault(obj) { return obj && obj.__esModule ? obj : { default: obj }; }
var W0, W1, X0, Y0, Z0, X1, Y1, Z1, X2, Y2, Z2, lambda00, phi00,
  // first point
  x0, y0, z0; // previous point

var centroidStream = {
  sphere: _noop.default,
  point: centroidPoint,
  lineStart: centroidLineStart,
  lineEnd: centroidLineEnd,
  polygonStart: function () {
    centroidStream.lineStart = centroidRingStart;
    centroidStream.lineEnd = centroidRingEnd;
  },
  polygonEnd: function () {
    centroidStream.lineStart = centroidLineStart;
    centroidStream.lineEnd = centroidLineEnd;
  }
};

// Arithmetic mean of Cartesian vectors.
function centroidPoint(lambda, phi) {
  lambda *= _math.radians, phi *= _math.radians;
  var cosPhi = (0, _math.cos)(phi);
  centroidPointCartesian(cosPhi * (0, _math.cos)(lambda), cosPhi * (0, _math.sin)(lambda), (0, _math.sin)(phi));
}
function centroidPointCartesian(x, y, z) {
  ++W0;
  X0 += (x - X0) / W0;
  Y0 += (y - Y0) / W0;
  Z0 += (z - Z0) / W0;
}
function centroidLineStart() {
  centroidStream.point = centroidLinePointFirst;
}
function centroidLinePointFirst(lambda, phi) {
  lambda *= _math.radians, phi *= _math.radians;
  var cosPhi = (0, _math.cos)(phi);
  x0 = cosPhi * (0, _math.cos)(lambda);
  y0 = cosPhi * (0, _math.sin)(lambda);
  z0 = (0, _math.sin)(phi);
  centroidStream.point = centroidLinePoint;
  centroidPointCartesian(x0, y0, z0);
}
function centroidLinePoint(lambda, phi) {
  lambda *= _math.radians, phi *= _math.radians;
  var cosPhi = (0, _math.cos)(phi),
    x = cosPhi * (0, _math.cos)(lambda),
    y = cosPhi * (0, _math.sin)(lambda),
    z = (0, _math.sin)(phi),
    w = (0, _math.atan2)((0, _math.sqrt)((w = y0 * z - z0 * y) * w + (w = z0 * x - x0 * z) * w + (w = x0 * y - y0 * x) * w), x0 * x + y0 * y + z0 * z);
  W1 += w;
  X1 += w * (x0 + (x0 = x));
  Y1 += w * (y0 + (y0 = y));
  Z1 += w * (z0 + (z0 = z));
  centroidPointCartesian(x0, y0, z0);
}
function centroidLineEnd() {
  centroidStream.point = centroidPoint;
}

// See J. E. Brock, The Inertia Tensor for a Spherical Triangle,
// J. Applied Mechanics 42, 239 (1975).
function centroidRingStart() {
  centroidStream.point = centroidRingPointFirst;
}
function centroidRingEnd() {
  centroidRingPoint(lambda00, phi00);
  centroidStream.point = centroidPoint;
}
function centroidRingPointFirst(lambda, phi) {
  lambda00 = lambda, phi00 = phi;
  lambda *= _math.radians, phi *= _math.radians;
  centroidStream.point = centroidRingPoint;
  var cosPhi = (0, _math.cos)(phi);
  x0 = cosPhi * (0, _math.cos)(lambda);
  y0 = cosPhi * (0, _math.sin)(lambda);
  z0 = (0, _math.sin)(phi);
  centroidPointCartesian(x0, y0, z0);
}
function centroidRingPoint(lambda, phi) {
  lambda *= _math.radians, phi *= _math.radians;
  var cosPhi = (0, _math.cos)(phi),
    x = cosPhi * (0, _math.cos)(lambda),
    y = cosPhi * (0, _math.sin)(lambda),
    z = (0, _math.sin)(phi),
    cx = y0 * z - z0 * y,
    cy = z0 * x - x0 * z,
    cz = x0 * y - y0 * x,
    m = (0, _math.hypot)(cx, cy, cz),
    w = (0, _math.asin)(m),
    // line weight = angle
    v = m && -w / m; // area weight multiplier
  X2.add(v * cx);
  Y2.add(v * cy);
  Z2.add(v * cz);
  W1 += w;
  X1 += w * (x0 + (x0 = x));
  Y1 += w * (y0 + (y0 = y));
  Z1 += w * (z0 + (z0 = z));
  centroidPointCartesian(x0, y0, z0);
}
function _default(object) {
  W0 = W1 = X0 = Y0 = Z0 = X1 = Y1 = Z1 = 0;
  X2 = new _index.Adder();
  Y2 = new _index.Adder();
  Z2 = new _index.Adder();
  (0, _stream.default)(object, centroidStream);
  var x = +X2,
    y = +Y2,
    z = +Z2,
    m = (0, _math.hypot)(x, y, z);

  // If the area-weighted ccentroid is undefined, fall back to length-weighted ccentroid.
  if (m < _math.epsilon2) {
    x = X1, y = Y1, z = Z1;
    // If the feature has zero length, fall back to arithmetic mean of point vectors.
    if (W1 < _math.epsilon) x = X0, y = Y0, z = Z0;
    m = (0, _math.hypot)(x, y, z);
    // If the feature still has an undefined ccentroid, then return.
    if (m < _math.epsilon2) return [NaN, NaN];
  }
  return [(0, _math.atan2)(y, x) * _math.degrees, (0, _math.asin)(z / m) * _math.degrees];
}