Display line that crosses 180th meridian
Draw a line across the 180th meridian using a GeoJSON source.
<!DOCTYPE html>
<html>
<head>
<meta charset="utf-8">
<title>Display line that crosses 180th meridian</title>
<meta name="viewport" content="initial-scale=1,maximum-scale=1,user-scalable=no">
<link href="https://api.mapbox.com/mapbox-gl-js/v3.8.0/mapbox-gl.css" rel="stylesheet">
<script src="https://api.mapbox.com/mapbox-gl-js/v3.8.0/mapbox-gl.js"></script>
<style>
body { margin: 0; padding: 0; }
#map { position: absolute; top: 0; bottom: 0; width: 100%; }
</style>
</head>
<body>
<div id="map"></div>
<script>
// TO MAKE THE MAP APPEAR YOU MUST
// ADD YOUR ACCESS TOKEN FROM
// https://account.mapbox.com
mapboxgl.accessToken = 'YOUR_MAPBOX_ACCESS_TOKEN';
const map = new mapboxgl.Map({
container: 'map',
// Choose from Mapbox's core styles, or make your own style with Mapbox Studio
style: 'mapbox://styles/mapbox/streets-v12',
center: [139.839478, 35.652832],
zoom: 2
});
map.on('load', () => {
map.addLayer({
'id': 'route',
'type': 'line',
'source': {
'type': 'geojson',
'data': {
'type': 'Feature',
'properties': {},
'geometry': createGeometry(false)
}
},
'layout': { 'line-cap': 'round' },
'paint': {
'line-color': '#007296',
'line-width': 4
}
});
map.addLayer({
'id': 'route-label',
'type': 'symbol',
'source': 'route',
'layout': {
'symbol-placement': 'line-center',
'text-field': 'Crosses the world'
}
});
map.addLayer({
'id': 'route-two',
'type': 'line',
'source': {
'type': 'geojson',
'data': {
'type': 'Feature',
'properties': {},
'geometry': createGeometry(true)
}
},
'layout': { 'line-cap': 'round' },
'paint': {
'line-color': '#F06317',
'line-width': 4
}
});
map.addLayer({
'id': 'route-two-label',
'type': 'symbol',
'source': 'route-two',
'layout': {
'symbol-placement': 'line-center',
'text-field': 'Crosses 180th meridian'
}
});
function createGeometry(doesCrossAntimeridian) {
const geometry = {
'type': 'LineString',
'coordinates': [
[-72.42187, -16.59408],
[140.27343, 35.67514]
]
};
// To draw a line across the 180th meridian,
// if the longitude of the second point minus
// the longitude of original (or previous) point is >= 180,
// subtract 360 from the longitude of the second point.
// If it is less than 180, add 360 to the second point.
if (doesCrossAntimeridian) {
const startLng = geometry.coordinates[0][0];
const endLng = geometry.coordinates[1][0];
if (endLng - startLng >= 180) {
geometry.coordinates[1][0] -= 360;
} else if (endLng - startLng < 180) {
geometry.coordinates[1][0] += 360;
}
}
return geometry;
}
});
</script>
</body>
</html>
This code snippet will not work as expected until you replace
YOUR_MAPBOX_ACCESS_TOKEN with an access token from your Mapbox account.import React, { useEffect, useRef } from 'react';
import mapboxgl from 'mapbox-gl';
import 'mapbox-gl/dist/mapbox-gl.css';
const MapboxExample = () => {
const mapContainerRef = useRef();
const mapRef = useRef();
useEffect(() => {
// TO MAKE THE MAP APPEAR YOU MUST
// ADD YOUR ACCESS TOKEN FROM
// https://account.mapbox.com
mapboxgl.accessToken = 'YOUR_MAPBOX_ACCESS_TOKEN';
mapRef.current = new mapboxgl.Map({
container: mapContainerRef.current,
style: 'mapbox://styles/mapbox/streets-v12',
center: [139.839478, 35.652832],
zoom: 2
});
mapRef.current.on('load', () => {
mapRef.current.addLayer({
id: 'route',
type: 'line',
source: {
type: 'geojson',
data: {
type: 'Feature',
properties: {},
geometry: createGeometry(false)
}
},
layout: { 'line-cap': 'round' },
paint: {
'line-color': '#007296',
'line-width': 4
}
});
mapRef.current.addLayer({
id: 'route-label',
type: 'symbol',
source: 'route',
layout: {
'symbol-placement': 'line-center',
'text-field': 'Crosses the world'
}
});
mapRef.current.addLayer({
id: 'route-two',
type: 'line',
source: {
type: 'geojson',
data: {
type: 'Feature',
properties: {},
geometry: createGeometry(true)
}
},
layout: { 'line-cap': 'round' },
paint: {
'line-color': '#F06317',
'line-width': 4
}
});
mapRef.current.addLayer({
id: 'route-two-label',
type: 'symbol',
source: 'route-two',
layout: {
'symbol-placement': 'line-center',
'text-field': 'Crosses 180th meridian'
}
});
function createGeometry(doesCrossAntimeridian) {
const geometry = {
type: 'LineString',
coordinates: [
[-72.42187, -16.59408],
[140.27343, 35.67514]
]
};
// To draw a line across the 180th meridian,
// if the longitude of the second point minus
// the longitude of original (or previous) point is >= 180,
// subtract 360 from the longitude of the second point.
// If it is less than 180, add 360 to the second point.
if (doesCrossAntimeridian) {
const startLng = geometry.coordinates[0][0];
const endLng = geometry.coordinates[1][0];
if (endLng - startLng >= 180) {
geometry.coordinates[1][0] -= 360;
} else if (endLng - startLng < 180) {
geometry.coordinates[1][0] += 360;
}
}
return geometry;
}
});
return () => {
mapRef.current.remove();
};
}, []);
return <div id="map" style={{ height: '100%' }} ref={mapContainerRef}></div>;
};
export default MapboxExample;
This code snippet will not work as expected until you replace
YOUR_MAPBOX_ACCESS_TOKEN with an access token from your Mapbox account.Was this example helpful?