d3-jsnext/src/geo/spherical.js

d3, but futuristic

import { ε, d3_asin } from '../math/trigonometry';
import { abs } from '../math/abs';

function d3_geo_spherical(cartesian) {
  return [
    Math.atan2(cartesian[1], cartesian[0]),
    d3_asin(cartesian[2])
  ];
}

function d3_geo_sphericalEqual(a, b) {
  return abs(a[0] - b[0]) < ε && abs(a[1] - b[1]) < ε;
}

export { d3_geo_sphericalEqual, d3_geo_spherical };