Filter symbols based on pitch and distance | Mapbox GL JS

Use ['pitch'] and ['distance-from-center'] expressions in the filter field of a symbol layer to remove large size POI labels in the far distance at high pitch, freeing up that screen real-estate for smaller road and street labels.

JavaScript

React

JavaScript

React


<!DOCTYPE html>
<html>
<head>
<meta charset="utf-8">
<title>Filter symbols based on pitch and distance</title>
<meta name="viewport" content="initial-scale=1,maximum-scale=1,user-scalable=no">
<link href="https://api.mapbox.com/mapbox-gl-js/v3.9.1/mapbox-gl.css" rel="stylesheet">
<script src="https://api.mapbox.com/mapbox-gl-js/v3.9.1/mapbox-gl.js"></script>
<style>
body { margin: 0; padding: 0; }
#map { position: absolute; top: 0; bottom: 0; width: 100%; }
</style>
</head>
<body>
<style>
    body {
        overflow: hidden;
    }

    body * {
        -webkit-touch-callout: none;
        -webkit-user-select: none;
        -moz-user-select: none;
        -ms-user-select: none;
        user-select: none;
    }

    .map {
        position: absolute;
        top: 0;
        bottom: 0;
        width: 100%;
    }
</style>
<script src="https://api.mapbox.com/mapbox-gl-js/plugins/mapbox-gl-compare/v0.4.0/mapbox-gl-compare.js"></script>
<link rel="stylesheet" href="https://api.mapbox.com/mapbox-gl-js/plugins/mapbox-gl-compare/v0.4.0/mapbox-gl-compare.css" type="text/css">
<div id="comparison-container">
    <div id="before" class="map"></div>
    <div id="after" class="map"></div>
</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 beforeMap = new mapboxgl.Map({
        container: 'before',
        style: 'mapbox://styles/mapbox/streets-v12',
        center: [-77.01866, 38.888],
        pitch: 75,
        zoom: 15
    });

    const afterMap = new mapboxgl.Map({
        container: 'after',
        // Choose from Mapbox's core styles, or make your own style with Mapbox Studio
        style: 'mapbox://styles/mapbox/streets-v12',
        center: [-77.01866, 38.888],
        pitch: 75,
        zoom: 15
    });

    afterMap.once('load', () => {
        const poiLayers = ['poi-label', 'transit-label'];

        for (const layerId of poiLayers) {
            const currFilter = afterMap.getFilter(layerId);
            // Add in an additional condition for filtering based on ["pitch"] and ["distance-from-center"]
            const updatedFilter = [
                'all',
                currFilter,
                [
                    'case',
                    // Always show the symbol when pitch <= 60
                    ['<=', ['pitch'], 60],
                    true,
                    // When pitch > 60, show the symbol only when it is close to the camera ( distance <= 2 )
                    [
                        'all',
                        ['<=', ['distance-from-center'], 2],
                        ['>', ['pitch'], 60]
                    ],
                    true,
                    // Hide in the remaining case, far and high pitch
                    false
                ]
            ];

            afterMap.setFilter(layerId, updatedFilter);
        }
    });
    const map = new mapboxgl.Compare(
        beforeMap,
        afterMap,
        '#comparison-container'
    );
</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.

JavaScript

React


import React, { useEffect, useRef } from 'react';
import mapboxgl from 'mapbox-gl';
import mapboxglCompare from 'mapbox-gl-compare';

import 'mapbox-gl/dist/mapbox-gl.css';
import 'mapbox-gl-compare/dist/mapbox-gl-compare.css';

// extend mapboxgl, adding the Compare class
mapboxgl.Compare = mapboxglCompare;

const mapStyle = { position: 'absolute', top: 0, bottom: 0, width: '100%' };

const MapboxExample = () => {
  const mapRef = useRef();
  const beforeMapContainerRef = useRef();
  const afterMapContainerRef = useRef();
  const comparisonContainerRef = useRef();

  useEffect(() => {
    // some development servers will run this hook more than once
    // return if the map has already been initialized
    if (mapRef.current) return;

    // TO MAKE THE MAP APPEAR YOU MUST
    // ADD YOUR ACCESS TOKEN FROM
    // https://account.mapbox.com
    mapboxgl.accessToken = 'YOUR_MAPBOX_ACCESS_TOKEN';

    const beforeMap = new mapboxgl.Map({
      container: beforeMapContainerRef.current,
      style: 'mapbox://styles/mapbox/streets-v12',
      center: [-77.01866, 38.888],
      pitch: 75,
      zoom: 15
    });

    const afterMap = new mapboxgl.Map({
      container: afterMapContainerRef.current,
      style: 'mapbox://styles/mapbox/streets-v12',
      center: [-77.01866, 38.888],
      pitch: 75,
      zoom: 15
    });

    afterMap.once('load', () => {
      const poiLayers = ['poi-label', 'transit-label'];

      for (const layerId of poiLayers) {
        const currFilter = afterMap.getFilter(layerId);

        const updatedFilter = [
          'all',
          currFilter,
          [
            'case',
            ['<=', ['pitch'], 60],
            true,
            ['all', ['<=', ['distance-from-center'], 2], ['>', ['pitch'], 60]],
            true,
            false
          ]
        ];

        afterMap.setFilter(layerId, updatedFilter);
      }
    });

    mapRef.current = new mapboxgl.Compare(
      beforeMap,
      afterMap,
      comparisonContainerRef.current
    );
  }, []);

  return (
    <div
      id="comparison-container"
      ref={comparisonContainerRef}
      style={{ height: '100%' }}
    >
      <div id="before" ref={beforeMapContainerRef} style={mapStyle}></div>
      <div id="after" ref={afterMapContainerRef} style={mapStyle}></div>
    </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.

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