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.

main.js
``````import 'ol/ol.css';
import Feature from 'ol/Feature';
import Map from 'ol/Map';
import Point from 'ol/geom/Point';
import VectorLayer from 'ol/layer/Vector';
import VectorSource from 'ol/source/Vector';
import View from 'ol/View';
import {Fill, RegularShape, Stroke, Style} from 'ol/style';

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

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

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

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

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

return vectorLayer;
}

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

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

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

layer0.setMap(map);

function bindInputs(id, layer) {
const 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);
``````
index.html
``````<!DOCTYPE html>
<html lang="en">
<meta charset="UTF-8">
<title>Layer Z-Index</title>
<!-- Pointer events polyfill for old browsers, see https://caniuse.com/#feat=pointer -->
<script src="https://unpkg.com/[email protected]/dist/elm-pep.js"></script>
<!-- The lines below are only needed for old environments like Internet Explorer and Android 4.x -->
<script src="https://cdn.polyfill.io/v3/polyfill.min.js?features=fetch,requestAnimationFrame,Element.prototype.classList,TextDecoder"></script>
<script src="https://cdnjs.cloudflare.com/ajax/libs/core-js/3.18.3/minified.js"></script>
<style>
.map {
width: 100%;
height:400px;
}
</style>
<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="main.js"></script>
</body>
</html>``````
package.json
``````{
"name": "layer-z-index",
"dependencies": {
"ol": "6.14.1"
},
"devDependencies": {
"parcel": "^2.0.0"
},
"scripts": {
"start": "parcel index.html",
"build": "parcel build --public-url . index.html"
}
}``````