Illustrates the use of layers partially overlapping their parent Map.

100% © IGN
index.js 
import TileWMS from "ol/source/TileWMS.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 ColorLayer from "@giro3d/giro3d/core/layer/ColorLayer.js";
import TiledImageSource from "@giro3d/giro3d/sources/TiledImageSource.js";
import ElevationLayer from "@giro3d/giro3d/core/layer/ElevationLayer.js";
import BilFormat from "@giro3d/giro3d/formats/BilFormat.js";
import Map from "@giro3d/giro3d/entities/Map.js";
import Inspector from "@giro3d/giro3d/gui/Inspector.js";

Instance.registerCRS(
  "EPSG:3946",
  "+proj=lcc +lat_1=45.25 +lat_2=46.75 +lat_0=46 +lon_0=3 +x_0=1700000 +y_0=5200000 +ellps=GRS80 +towgs84=0,0,0,0,0,0,0 +units=m +no_defs",
);

const extent = new Extent(
  "EPSG:3946",
  1837816.94334,
  1847692.32501,
  5170036.4587,
  5178412.82698,
);

const instance = new Instance({
  target: "view",
  crs: "EPSG:3946",
});

const map = new Map({ extent, hillshading: true, backgroundColor: "white" });
instance.add(map);

// Adds a WMS imagery layer
const colorSource = new TiledImageSource({
  source: new TileWMS({
    url: "https://data.geopf.fr/wms-r",
    projection: "EPSG:3946",
    params: {
      LAYERS: ["HR.ORTHOIMAGERY.ORTHOPHOTOS"],
      FORMAT: "image/jpeg",
    },
  }),
});

// Define a smaller extent for the layer.
const layerExtent = extent.withMargin(-1000, -1000);

const colorLayer = new ColorLayer({
  name: "wms_imagery",
  source: colorSource,
  extent: layerExtent,
});
map.addLayer(colorLayer);

// Adds a WMS elevation layer
const elevationSource = new TiledImageSource({
  source: new TileWMS({
    url: "https://data.geopf.fr/wms-r",
    projection: "EPSG:3946",
    crossOrigin: "anonymous",
    params: {
      LAYERS: ["ELEVATION.ELEVATIONGRIDCOVERAGE.HIGHRES"],
      FORMAT: "image/x-bil;bits=32",
    },
  }),
  format: new BilFormat(),
  noDataValue: -1000,
});

const elevationLayer = new ElevationLayer({
  name: "wms_elevation",
  extent,
  source: elevationSource,
});

map.addLayer(elevationLayer);

instance.view.camera.position.set(extent.west, extent.south, 2000);

const controls = new MapControls(instance.view.camera, instance.domElement);
controls.target = extent.centerAsVector3();
controls.saveState();
controls.enableDamping = true;
controls.dampingFactor = 0.2;
controls.maxPolarAngle = Math.PI / 2.3;
instance.view.setControls(controls);

Inspector.attach("inspector", instance);
index.html 
<!doctype html>
<html lang="en">
  <head>
    <title>Partial layers</title>
    <meta charset="UTF-8" />
    <meta name="name" content="partial_layer" />
    <meta
      name="description"
      content="Illustrates the use of layers partially overlapping their parent Map."
    />
    <meta name="viewport" content="width=device-width, initial-scale=1.0" />

    <link rel="icon" href="https://giro3d.org/images/favicon.svg" />
    <link
      href="https://giro3d.org/assets/bootstrap-custom.css"
      rel="stylesheet"
    />
    <script src="https://giro3d.org/assets/bootstrap.bundle.min.js"></script>
    <link
      rel="stylesheet"
      type="text/css"
      href="https://giro3d.org/next/css/example.css"
    />
  </head>

  <body>
    <div id="view" class="m-0 p-0 w-100 h-100"></div>
    <div
      id="inspector"
      class="position-absolute top-0 start-0 mh-100 overflow-auto"
    ></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": "partial_layer",
    "dependencies": {
        "@giro3d/giro3d": "git+https://gitlab.com/giro3d/giro3d.git"
    },
    "devDependencies": {
        "vite": "^3.2.3"
    },
    "scripts": {
        "start": "vite",
        "build": "vite build"
    }
}