d3-geo-voronoi/src/cartesian.js

Spherical Voronoi Diagram and Delaunay Triangulation

import { asin, atan2, cos, sin, sqrt } from "./math.js";

export function spherical(cartesian) {
  return [atan2(cartesian[1], cartesian[0]), asin(cartesian[2])];
}

export function cartesian(spherical) {
  const lambda = spherical[0],
    phi = spherical[1],
    cosPhi = cos(phi);
  return [cosPhi * cos(lambda), cosPhi * sin(lambda), sin(phi)];
}

export function cartesianDot(a, b) {
  return a[0] * b[0] + a[1] * b[1] + a[2] * b[2];
}

export function cartesianCross(a, b) {
  return [
    a[1] * b[2] - a[2] * b[1],
    a[2] * b[0] - a[0] * b[2],
    a[0] * b[1] - a[1] * b[0],
  ];
}

// TODO return a
export function cartesianAddInPlace(a, b) {
  (a[0] += b[0]), (a[1] += b[1]), (a[2] += b[2]);
}

export function cartesianAdd(a, b) {
  return [a[0] + b[0], a[1] + b[1], a[2] + b[2]];
}

export function cartesianScale(vector, k) {
  return [vector[0] * k, vector[1] * k, vector[2] * k];
}

// TODO return d
export function cartesianNormalizeInPlace(d) {
  var l = sqrt(d[0] * d[0] + d[1] * d[1] + d[2] * d[2]);
  (d[0] /= l), (d[1] /= l), (d[2] /= l);
}

export function cartesianNormalize(d) {
  var l = sqrt(d[0] * d[0] + d[1] * d[1] + d[2] * d[2]);
  return [d[0] / l, d[1] / l, d[2] / l];
}