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Layer Z-Index


Example of ordering layers using Z-index.

There are are two managed layers (square and triangle) and one unmanaged layer (star).
The Z-index determines the rendering order; with {square: 1, triangle: 0, star: unmanaged} indices, the rendering order is triangle, square and star on top.

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index.html<!DOCTYPE html>
<html lang="en">
  <head>
    <title>Layer Z-Index</title>
    <!-- The line below is only needed for old environments like Internet Explorer and Android 4.x -->
    <script src="https://cdn.polyfill.io/v2/polyfill.min.js?features=requestAnimationFrame,Element.prototype.classList,URL"></script>
    <style>
      .map {
        width: 100%;
        height:400px;
      }
    </style>
  </head>
  <body>
    <div id="map" class="map"></div>
    <div>
      <label for="idx1">
        <input type="number" id="idx1"></input>
        Square layer Z-index
      </label></br>

      <label for="idx2">
        <input type="number" id="idx2"></input>
        Triangle layer Z-index
      </label>
    </div>
    <script src="index.js"></script>
  </body>
</html>
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index.jsimport 'ol/ol.css';
import Feature from 'ol/Feature';
import Map from 'ol/Map';
import View from 'ol/View';
import Point from 'ol/geom/Point';
import VectorLayer from 'ol/layer/Vector';
import VectorSource from 'ol/source/Vector';
import {Fill, RegularShape, Stroke, Style} from 'ol/style';


var stroke = new Stroke({color: 'black', width: 1});

var styles = {
  'square': new Style({
    image: new RegularShape({
      fill: new Fill({color: 'blue'}),
      stroke: stroke,
      points: 4,
      radius: 80,
      angle: Math.PI / 4
    })
  }),
  'triangle': new Style({
    image: new RegularShape({
      fill: new Fill({color: 'red'}),
      stroke: stroke,
      points: 3,
      radius: 80,
      rotation: Math.PI / 4,
      angle: 0
    })
  }),
  'star': new Style({
    image: new RegularShape({
      fill: new Fill({color: 'green'}),
      stroke: stroke,
      points: 5,
      radius: 80,
      radius2: 4,
      angle: 0
    })
  })
};


function createLayer(coordinates, style, zIndex) {
  var feature = new Feature(new Point(coordinates));
  feature.setStyle(style);

  var source = new VectorSource({
    features: [feature]
  });

  var vectorLayer = new VectorLayer({
    source: source
  });
  vectorLayer.setZIndex(zIndex);

  return vectorLayer;
}

var layer0 = createLayer([40, 40], styles['star'], 0);
var layer1 = createLayer([0, 0], styles['square'], 1);
var layer2 = createLayer([0, 40], styles['triangle'], 0);

var layers = [];
layers.push(layer1);
layers.push(layer2);

var map = new Map({
  layers: layers,
  target: 'map',
  view: new View({
    center: [0, 0],
    zoom: 18
  })
});

layer0.setMap(map);


function bindInputs(id, layer) {
  var idxInput = document.getElementById('idx' + id);
  idxInput.onchange = function() {
    layer.setZIndex(parseInt(this.value, 10) || 0);
  };
  idxInput.value = String(layer.getZIndex());
}
bindInputs(1, layer1);
bindInputs(2, layer2);
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package.json{
  "name": "layer-z-index",
  "dependencies": {
    "ol": "6.1.1"
  },
  "devDependencies": {
    "parcel": "1.11.0"
  },
  "scripts": {
    "start": "parcel index.html",
    "build": "parcel build --experimental-scope-hoisting --public-url . index.html"
  }
}