Last active
May 25, 2023 18:35
-
-
Save jbranigan/9fd06e4103ccae2335c35d16f2a8c351 to your computer and use it in GitHub Desktop.
Find the nearest point on a highway to the mouse cursor
This file contains bidirectional Unicode text that may be interpreted or compiled differently than what appears below. To review, open the file in an editor that reveals hidden Unicode characters.
Learn more about bidirectional Unicode characters
| <!DOCTYPE html> | |
| <html> | |
| <head> | |
| <meta charset="utf-8" /> | |
| <title>Get nearest highway to the mouse pointer</title> | |
| <meta name="viewport" content="initial-scale=1,maximum-scale=1,user-scalable=no" /> | |
| <link href="https://api.mapbox.com/mapbox-gl-js/v1.12.0/mapbox-gl.css" rel="stylesheet" /> | |
| <style> | |
| body { | |
| margin: 0; | |
| padding: 0; | |
| } | |
| #map { | |
| position: absolute; | |
| top: 0; | |
| bottom: 0; | |
| width: 100%; | |
| } | |
| </style> | |
| </head> | |
| <body> | |
| <div id="map"></div> | |
| <script src="https://api.mapbox.com/mapbox-gl-js/v1.12.0/mapbox-gl.js"></script> | |
| <script src='https://cdn.jsdelivr.net/npm/@turf/turf@6/turf.min.js'></script> | |
| <script> | |
| mapboxgl.accessToken = 'pk.eyJ1IjoiYnJhbmlnYW4iLCJhIjoiY2tlMWtmcndiMDA4bzJxbngzbm9zaDg3YyJ9.GvTC2gaBQE4H79yxpPPDCg'; | |
| var map = new mapboxgl.Map({ | |
| container: 'map', | |
| style: 'mapbox://styles/mapbox/streets-v11', | |
| center: [-107, 43], | |
| zoom: 6.25 | |
| }); | |
| map.on('load', function () { | |
| map.addSource('point', { | |
| type: 'geojson', | |
| data: { "type": "FeatureCollection", "features": [] } | |
| }); | |
| map.addLayer({ | |
| id: 'nearest-point', | |
| source: 'point', | |
| type: 'circle', | |
| paint: { | |
| 'circle-color': 'purple', | |
| 'circle-radius': 8, | |
| 'circle-opacity': 0.5 | |
| } | |
| }); | |
| map.on('mousemove', function (e) { | |
| // set some padding on the mouse cursor and find any highways nearby | |
| const pixels = 20; | |
| const features = map.queryRenderedFeatures([ | |
| [e.point.x - pixels, e.point.y - pixels], | |
| [e.point.x + pixels, e.point.y + pixels] | |
| ], { layers: ['road-motorway-trunk', 'road-primary'] } | |
| ); | |
| if (features.length > 0) { | |
| // convert cursor location from pixel coordinates to lon/lat | |
| const cursorLocation = turf.point(map.unproject(e.point).toArray()); | |
| // find the nearest place on the road to the cursor and add it to the map layer | |
| const snappedPoint = turf.nearestPointOnLine(features[0], cursorLocation); | |
| map.getSource('point').setData({ "type": "FeatureCollection", "features": [ snappedPoint ] }); | |
| } else { | |
| map.getSource('point').setData({ "type": "FeatureCollection", "features": [] }); | |
| } | |
| }); | |
| }); | |
| </script> | |
| </body> | |
| </html> |
Sign up for free
to join this conversation on GitHub.
Already have an account?
Sign in to comment