Retrieve the pixel value of a layer at given coordinates.
Use the getPixel() method to change the mouse pointer when hovering a non-transparent pixel on the map.
import { get as getProjection } from "ol/proj.js";
import { TileWMS } from "ol/source.js";
import { Vector2, Vector3 } from "three";
import { MapControls } from "three/examples/jsm/controls/MapControls.js";
import Coordinates from "@giro3d/giro3d/core/geographic/Coordinates.js";
import CoordinateSystem from "@giro3d/giro3d/core/geographic/CoordinateSystem.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 TiledImageSource from "@giro3d/giro3d/sources/TiledImageSource.js";
import WmtsSource from "@giro3d/giro3d/sources/WmtsSource.js";
function bindColorPicker(id, onChange) {
const element = document.getElementById(id);
if (!(element instanceof HTMLInputElement)) {
throw new Error(
"invalid binding element: expected HTMLInputElement, got: " +
element.constructor.name,
);
}
element.oninput = function oninput() {
// Let's change the classification color with the color picker value
const hexColor = element.value;
onChange(new Color(hexColor));
};
const externalFunction = (v) => {
element.value = `#${new Color(v).getHexString()}`;
onChange(element.value);
};
return [externalFunction, new Color(element.value), element];
}
const extent = new Extent(
CoordinateSystem.epsg3857,
-20037508.342789244,
20037508.342789244,
-20048966.1,
20048966.1,
);
const instance = new Instance({
target: "view",
crs: extent.crs,
backgroundColor: "black",
});
const camPos = new Vector3(258767.3, 6247882.8, 6872.5);
instance.view.camera.position.set(camPos.x, camPos.y, camPos.z);
const controls = new MapControls(instance.view.camera, instance.domElement);
instance.view.setControls(controls);
controls.target.set(camPos.x, camPos.y + 1, 0);
const map = new Map({
extent,
backgroundColor: "gray",
maxSubdivisionLevel: 19,
lighting: {
enabled: true,
zFactor: 8,
},
terrain: false,
});
instance.add(map);
const capabilitiesUrl =
"https://data.geopf.fr/wmts?SERVICE=WMTS&VERSION=1.0.0&REQUEST=GetCapabilities";
const wmsLayer = new ColorLayer({
name: "museums",
source: new TiledImageSource({
httpTimeout: 10000,
source: new TileWMS({
url: "https://data.geopf.fr/wms-v/wms?SERVICE=WMS&VERSION=1.3.0",
params: { LAYERS: "POI.MUSEUM", TILED: true },
crossOrigin: "anonymous",
projection: getProjection("EPSG:3857"),
}),
}),
});
async function initializeWmts() {
const orthophotoWmts = await WmtsSource.fromCapabilities(capabilitiesUrl, {
layer: "HR.ORTHOIMAGERY.ORTHOPHOTOS",
});
const layer = new ColorLayer({
name: "orthophotos",
extent: map.extent,
source: orthophotoWmts,
});
layer.userData.zOrder = 0;
await Promise.all([map.addLayer(layer), map.addLayer(wmsLayer)]);
const [setColor, _, colorPicker] = bindColorPicker("color", () => {});
instance.domElement.addEventListener("pointermove", (event) => {
const canvasCoords = instance.eventToCanvasCoords(event, new Vector2());
const results = map.pick(canvasCoords);
if (results && results.length > 0) {
const point = results[0].point;
const coordinates = new Coordinates(
instance.coordinateSystem,
point.x,
point.y,
);
const hit = wmsLayer.getPixel({ coordinates, size: 10 });
if (hit && hit.length > 0) {
setColor(hit[0]);
}
colorPicker.style.display = hit ? "block" : "none";
instance.domElement.style.cursor = hit ? "pointer" : "";
} else {
colorPicker.style.display = "none";
instance.domElement.style.cursor = "";
}
});
}
Inspector.attach("inspector", instance);
initializeWmts();
<!doctype html>
<html lang="en">
<head>
<title>Sample layer color</title>
<meta charset="UTF-8" />
<meta name="name" content="layer-get-pixel" />
<meta
name="description"
content="Retrieve the pixel value of a layer at given coordinates."
/>
<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/examples/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>
<div class="side-pane-with-status-bar" style="width: 10rem">
<div class="card">
<div class="card-header">Parameters</div>
<div class="card-body">
<!-- Color -->
<label class="form-check-label w-100 mb-2" for="color"
>Picked color</label
>
<input
disabled
type="color"
class="form-control form-control-color float-end w-100"
id="color"
value="#ffffff"
title="color"
autocomplete="off"
/>
</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>
{
"name": "layer-get-pixel",
"dependencies": {
"@giro3d/giro3d": "1.0.0"
},
"devDependencies": {
"vite": "^3.2.3"
},
"scripts": {
"start": "vite",
"build": "vite build"
}
}import { defineConfig } from "vite";
export default defineConfig({
build: {
target: 'esnext',
},
optimizeDeps: {
esbuildOptions: {
target: 'esnext',
},
},
})