Display HTML labels in the 3D scene.

100% © IGN

Labels are HTML elements produced by Three.js' CSS2DRenderer. They can be styled using normal CSS styling.

index.js
import { GeoJSON } from "ol/format.js";
import { Fill, Stroke, Style } from "ol/style.js";
import TileWMS from "ol/source/TileWMS.js";

import { MathUtils, Vector2, Vector3 } from "three";
import { MapControls } from "three/examples/jsm/controls/MapControls.js";
import { CSS2DObject } from "three/examples/jsm/renderers/CSS2DRenderer.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 Map from "@giro3d/giro3d/entities/Map.js";
import Inspector from "@giro3d/giro3d/gui/Inspector.js";
import VectorSource from "@giro3d/giro3d/sources/VectorSource.js";
import TiledImageSource from "@giro3d/giro3d/sources/TiledImageSource.js";

// This example is based on planar_vector example, adding labels on features.
// You can directly jump to `geoJsonLayer.source.addEventListener('featuresloadend', ...)`,
// as the rest is similar.

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: extent.crs,
});

const map = new Map({ extent });
instance.add(map);

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);

// Function to look at an extent from top
function lookTopDownAt(lookAtExtent, lookAtAltitude = 0) {
  const camera = instance.view.camera;

  const fov = camera.fov;

  const aspect = camera.aspect;

  const hFov = MathUtils.degToRad(fov) / 2;

  const dims = lookAtExtent.dimensions();

  const altitude = (Math.max(dims.x / aspect, dims.y) / Math.tan(hFov)) * 0.5;
  const position = lookAtExtent
    .centerAsVector3()
    .add(new Vector3(0, 0, altitude));
  const lookAt = lookAtExtent.centerAsVector3();

  lookAt.z = lookAtAltitude;

  // place camera above
  camera.position.copy(position);

  // look down
  camera.lookAt(lookAt);

  // make sure the camera isn't rotating around its view axis
  camera.rotation.z = 0;
  camera.rotation.x = 0.01; // quickfix to avoid bizarre jumps

  controls.target.copy(lookAt);
  controls.saveState();

  instance.notifyChange(camera);
}

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

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

const style = new Style({
  fill: new Fill({
    color: "rgba(255, 165, 0, 0.2)",
  }),
  stroke: new Stroke({
    color: "white",
    width: 2,
  }),
});

const geojsonSource = new VectorSource({
  data: {
    url: "https://raw.githubusercontent.com/iTowns/iTowns2-sample-data/master/lyon.geojson",
    format: new GeoJSON(),
  },
  style,
});

const geoJsonLayer = new ColorLayer({
  name: "geojson",
  extent,
  source: geojsonSource,
});

map.addLayer(geoJsonLayer).then(() => {
  // Traverse the OpenLayers features that were added
  for (const feature of geojsonSource.getFeatures()) {
    // Create a label for each feature

    const text = document.createElement("div");
    // Virtually any inner markup is supported, here we're just inserting text
    text.innerText = feature.get("nom");
    text.title = `${feature.get("numero_arrondissement")}e arrondissement`;

    // Any CSS style is supported
    text.style.color = "#ffffff";
    text.style.padding = "0.2em 1em";
    text.style.maxWidth = "200px";
    text.style.border = "2px solid #cccccc";
    text.style.backgroundColor = "#080808";
    text.style.textAlign = "center";
    text.style.opacity = "80%";

    // Adding the label requires a Vector3 position, let's compute that
    // We'll position the label at the center of the geometry extent
    const olExtent = feature.getGeometry().getExtent();
    const giro3dExtent = new Extent(
      "EPSG:3946",
      olExtent[0],
      olExtent[2],
      olExtent[1],
      olExtent[3],
    );
    if (!giro3dExtent.isInside(extent)) {
      // The extent of the feature is not fully inside the map extent,
      // let's crop it to make sure the label will be inside the map
      giro3dExtent.intersect(extent);
    }
    const position = new Vector2();
    giro3dExtent.centerAsVector2(position);

    // Create our label and position it
    const label = new CSS2DObject(text);
    label.position.set(position.x, position.y, 0);
    label.updateMatrixWorld();
    // Give it a name so it shows up nicely in the inspector
    label.name = `${feature.get("nom")}`;
    // Simply add it to our instance
    // (we could also create a dedicated THREE.Group to have all the labels inside)
    instance.add(label);

    // By default, labels don't have mouse interaction enabled (pointerEvents = 'none')
    // Let's change that so we can click on it to zoom on it
    text.style.cursor = "pointer";
    text.style.pointerEvents = "auto";
    // Controls can interfer with the click event
    // e.g. this click event is triggered when we drag the map and the dragging ends on a label
    // but the mouseover is not, so use that to know if the user really wants to click
    // on the label.
    text.addEventListener("mouseover", () => {
      text.setAttribute("giro3d_over", "on");
    });
    text.addEventListener("mouseout", () => {
      text.removeAttribute("giro3d_over");
    });
    text.addEventListener("click", () => {
      if (text.getAttribute("giro3d_over")) {
        lookTopDownAt(giro3dExtent);
      }
    });
  }
  instance.notifyChange(geoJsonLayer);
});

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

Inspector.attach("inspector", instance);
index.html
<!doctype html>
<html lang="en">
  <head>
    <title>HTML labels</title>
    <meta charset="UTF-8" />
    <meta name="name" content="htmllabels" />
    <meta name="description" content="Display HTML labels in the 3D scene." />
    <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/latest/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": "htmllabels",
    "dependencies": {
        "@giro3d/giro3d": "0.39.0"
    },
    "devDependencies": {
        "vite": "^3.2.3"
    },
    "scripts": {
        "start": "vite",
        "build": "vite build"
    }
}