spherical-geometry-js

Spherical Geometry Library ·

This library provides classes and functions for the computation of geometric data on the surface of the Earth.

This library ports a small but useful subset of classes from the Google Maps Javascript API version 3, to use as a separate module or in node. I also try to have readable code, so that you can understand what calculations are being made.

How to use

import * as geometry from 'spherical-geometry-js';

Or import individual modules

import { computeArea } from 'spherical-geometry-js';
import computeArea from 'spherical-geometry-js/compute-area';

Notes:

• The API is nearly identical to the Google Maps Javascript API.
• Functions automatically convert coordinate objects into LatLngs. See convertLatLng for more details.
• All computed lengths are returned in meters.

API

The full API of the library is described in the typings file.

Classes and libraries ported from the Google Maps Javascript API:

• google.maps.geometry.spherical
• google.maps.LatLng

This module tries to maintain full API compatibility with Google Maps so it can be used as a drop-in replacement.

For convenience, LatLng includes some extra methods.

const latlng = new LatLng(123, 56);
// Alias getters for longitude and latitude

latlng.x === latlng.lng();
latlng.y === latlng.lat();

latlng[0] === latlng.lng();
latlng[1] === latlng.lat();

import { equalLatLngs } from 'spherical-geometry-js';

equalLatLngs(latlng1, latlng2) === latlng1.equals(latlng2);

convertLatLng(like) ⇒ LatLng

import { LatLng, convertLatLng } from 'spherical-geometry-js';

convertLatLng({ lat: 123, lng: 56 }).equals(new LatLng(123, 56));
convertLatLng([56, 123]).equals(new LatLng(123, 56));
convertLatLng({ x: 56, y: 123 }).equals(new LatLng(123, 56));

Helper function that tries to convert and object into a LatLng. Tries a few different methods:

• If instanceof LatLng, clone the object and return it.

• If it has lat and lng properties...

  2a. if the properties are functions (like Google LatLngs), use the lat() and lng() values as latitude and longitude.

  2b. otherwise get lat and lng, parse them as floats and use them.

• If it has lat and long properties, parse them as floats use them.

• If it has lat and lon properties, parse them as floats use them.

• If it has latitude and longitude properties, parse them as floats use them.

• If it has number values for 0 and 1 (aka an array of two numbers), use 1 as latitude and 0 as longitude.

• If it has x and y properties, try using y as latitude and x and longitude.