Illustrates the use of mask layers.

Mask layer
100% © Mapbox

A MaskLayer can be used to mask part of a map. By default, the transparent part of the mask makes the map transparent. By inverting the mask, the transparent part of the mask makes the map opaque.

index.js
import XYZ from 'ol/source/XYZ.js';
import { Fill, Stroke, Style } from 'ol/style.js';
import { GeoJSON } from 'ol/format.js';
import { MapControls } from 'three/examples/jsm/controls/MapControls.js';

import Extent from '@giro3d/giro3d/core/geographic/Extent.js';
import Instance from '@giro3d/giro3d/core/Instance.js';
import TiledImageSource from '@giro3d/giro3d/sources/TiledImageSource.js';
import ColorLayer from '@giro3d/giro3d/core/layer/ColorLayer.js';
import Map from '@giro3d/giro3d/entities/Map.js';
import Inspector from '@giro3d/giro3d/gui/Inspector.js';
import MaskLayer, { MaskMode } from '@giro3d/giro3d/core/layer/MaskLayer.js';
import VectorSource from '@giro3d/giro3d/sources/VectorSource.js';



// Defines geographic extent: CRS, min/max X, min/max Y
const extent = Extent.fromCenterAndSize('EPSG:3857', { x: 260000, y: 6251379 }, 32000, 32000);

// `viewerDiv` will contain giro3d' rendering area (the canvas element)
const viewerDiv = document.getElementById('viewerDiv');

// Creates a giro3d instance
const instance = new Instance(viewerDiv, {
    crs: extent.crs(),
    renderer: {
        clearColor: false,
    },
});

const apiKey = 'pk.eyJ1IjoidG11Z3VldCIsImEiOiJjbGJ4dTNkOW0wYWx4M25ybWZ5YnpicHV6In0.KhDJ7W5N3d1z3ArrsDjX_A';

// Adds the map that will contain the layers.
const map = new Map('Paris', { extent, segments: 128 });

instance.add(map);

// Adds a satellite basemap
const basemap = new ColorLayer({
    name: 'basemap',
    extent,
    source: new TiledImageSource({
        source: new XYZ({
            url: `https://api.mapbox.com/v4/mapbox.satellite/{z}/{x}/{y}.webp?access_token=${apiKey}`,
            projection: extent.crs(),
            crossOrigin: 'anonymous',
        }),
    }),
});
map.addLayer(basemap);

const outlineStyle = new Style({
    stroke: new Stroke({ color: 'red', width: 2 }),
});

// Display the footprint using a red outline. This layer is not necessary for the mask to work,
// and is only present for illustration purposes.
const outline = new ColorLayer({
    name: 'outline',
    source: new VectorSource({
        format: new GeoJSON(),
        data: 'https://3d.oslandia.com/giro3d/vectors/paris.geojson',
        style: outlineStyle,
    }),
});

map.addLayer(outline);

// The mask layer uses an opaque fill style.
const maskStyle = new Style({
    fill: new Fill({ color: 'white' }),
});

// Create the actual mask layer with the same source as the outline.
const mask = new MaskLayer({
    name: 'mask',
    source: new VectorSource({
        format: new GeoJSON(),
        data: 'https://3d.oslandia.com/giro3d/vectors/paris.geojson',
        style: maskStyle,
    }),
});

map.addLayer(mask);

// Sets the camera position
const center = extent.centerAsVector3();
instance.camera.camera3D.position.set(center.x, center.y - 1, 40000);

// Creates controls
const controls = new MapControls(
    instance.camera.camera3D,
    viewerDiv,
);

// Then looks at extent's center
controls.target = center;
controls.saveState();

controls.enableDamping = true;
controls.dampingFactor = 0.2;
controls.maxPolarAngle = Math.PI / 2.3;

instance.useTHREEControls(controls);

Inspector.attach(document.getElementById('panelDiv'), instance);

// Bind events


document.getElementById('layerState').addEventListener('change', e => {
    const newMode = parseInt(e.target.value, 10);

    switch (newMode) {
        case 1:
            mask.visible = true;
            mask.maskMode = MaskMode.Normal;
            break;
        case 2:
            mask.visible = true;
            mask.maskMode = MaskMode.Inverted;
            break;
        default:
            mask.visible = false;
            break;
    }

    instance.notifyChange(map);
});
index.html
<!DOCTYPE html>
<html lang="en">

<head>
  <meta charset="UTF-8">
  <title>Giro3D - Mask layers</title>
  <link href="https://cdn.jsdelivr.net/npm/bootstrap@5.3.2/dist/css/bootstrap.min.css" rel="stylesheet" integrity="sha384-T3c6CoIi6uLrA9TneNEoa7RxnatzjcDSCmG1MXxSR1GAsXEV/Dwwykc2MPK8M2HN" crossorigin="anonymous">
  <link rel="stylesheet" href="https://cdn.jsdelivr.net/npm/bootstrap-icons@1.11.3/font/bootstrap-icons.min.css">
  <script src="https://cdn.jsdelivr.net/npm/bootstrap@5.3.2/dist/js/bootstrap.bundle.min.js" integrity="sha384-C6RzsynM9kWDrMNeT87bh95OGNyZPhcTNXj1NW7RuBCsyN/o0jlpcV8Qyq46cDfL" crossorigin="anonymous"></script>
  <style>
    body {
      padding: 0;
      margin: 0;
      width: 100vw;
      height: 100vh;
    }

    #viewerDiv {
      width: 100%;
      height: 100%;
    }

    #panelDiv {
      position: absolute;
      top: 0;
      left: 0;
    }
    #viewerDiv canvas {
  background-image: linear-gradient(45deg, #aaaaaa 25%, transparent 25%), linear-gradient(-45deg, #aaaaaa 25%, transparent 25%), linear-gradient(45deg, transparent 75%, #aaaaaa 75%), linear-gradient(-45deg, transparent 75%, #aaaaaa 75%);
  background-size: 20px 20px;
  background-position: 0 0, 0 10px, 10px -10px, -10px 0px;
}

  </style>
</head>

<body>
  <div id="viewerDiv"></div>
  <div id="panelDiv"></div>
  <div class="m-2 position-absolute top-0 end-0">
    <div class="card">
        <h5 class="card-header">Mask layer</h5>

        <div class="card-body">
            <form>
                <div class="row">
                    <div class="dropdown">
                        <select class="btn btn-primary dropdown-toggle" id="layerState">
                            <option value="0">Disabled</option>
                            <option value="1" selected>Enabled</option>
                            <option value="2">Enabled (invert mask)</option>
                        </select>
                    </div>
                </div>
            </form>
        </div>
    </div>
</div>

  <script type="module" src="index.js"></script>
  <script>
    /* activate popovers */
    const popoverTriggerList = [].slice.call(document.querySelectorAll('[data-bs-toggle="popover"]'));
    popoverTriggerList.map(
      // bootstrap is used as script in the template, disable warning about undef
      // eslint-disable-next-line no-undef
      popoverTriggerEl => new bootstrap.Popover(popoverTriggerEl, {
        trigger: 'hover',
        placement: 'left',
        content: document.getElementById(popoverTriggerEl.getAttribute('data-bs-content')).innerHTML,
        html: true,
      }),
    );
  </script>
</body>

</html>
package.json
{
  "name": "mask_layer",
  "dependencies": {
    "@giro3d/giro3d": "0.33.1"
  },
  "devDependencies": {
    "vite": "^3.2.3"
  },
  "scripts": {
    "start": "vite",
    "build": "vite build"
  }
}