Illustrates how transparency in maps work.
Transparency in maps (and any other 3D object) is a tricky problem. Due to limitations in how 3D renderers work, it is not generally possible to correctly display overlapping transparent objects. For example, set the opacity of at least 2 maps to less than 100%, rotate the camera around, and observe various rendering issues, such as missing map tiles.
import colormap from "colormap";
import { Color, DoubleSide } from "three";
import { MapControls } from "three/examples/jsm/controls/MapControls.js";
import { Fill, Stroke, Style } from "ol/style.js";
import TileWMS from "ol/source/TileWMS.js";
import GeoJSON from "ol/format/GeoJSON.js";
import BilFormat from "@giro3d/giro3d/formats/BilFormat.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 ElevationLayer from "@giro3d/giro3d/core/layer/ElevationLayer.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 ColorMap from "@giro3d/giro3d/core/layer/ColorMap.js";
function bindToggle(id, onChange) {
const element = document.getElementById(id);
if (!(element instanceof HTMLInputElement)) {
throw new Error(
"invalid binding element: expected HTMLButtonElement, got: " +
element.constructor.name,
);
}
element.oninput = function oninput() {
onChange(element.checked);
};
const callback = (v) => {
element.checked = v;
onChange(element.checked);
};
return [callback, element.checked, element];
}
function bindSlider(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() {
onChange(element.valueAsNumber);
};
const setValue = (v) => {
element.valueAsNumber = v;
onChange(element.valueAsNumber);
};
const initialValue = element.valueAsNumber;
return [setValue, initialValue, element];
}
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",
backgroundColor: null,
});
const terrainMap = new Map({ extent, side: DoubleSide, hillshading: true });
instance.add(terrainMap);
const min = 100;
const max = 300;
const values = colormap({ colormap: "viridis", nshades: 256 });
const colors = values.map((v) => new Color(v));
const colorMap = new ColorMap(colors, min, max);
const elevationLayer = new ElevationLayer({
name: "terrain",
extent,
colorMap,
minmax: { min, max },
source: 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,
}),
});
terrainMap.addLayer(elevationLayer);
const orthophotoMap = new Map({ extent, side: DoubleSide });
instance.add(orthophotoMap);
const orthophotoLayer = new ColorLayer({
name: "orthophoto",
extent,
source: new TiledImageSource({
source: new TileWMS({
url: "https://data.geopf.fr/wms-r",
projection: "EPSG:3946",
params: {
LAYERS: ["HR.ORTHOIMAGERY.ORTHOPHOTOS"],
FORMAT: "image/jpeg",
},
}),
}),
});
orthophotoMap.addLayer(orthophotoLayer);
const vectorMap = new Map({ extent, side: DoubleSide, backgroundOpacity: 0 });
instance.add(vectorMap);
const geoJsonLayer = new ColorLayer({
name: "geojson",
extent,
source: new VectorSource({
data: {
url: "https://raw.githubusercontent.com/iTowns/iTowns2-sample-data/master/lyon.geojson",
format: new GeoJSON(),
},
dataProjection: "EPSG:3946",
style: new Style({
fill: new Fill({
color: "rgba(255, 165, 0, 0.6)",
}),
stroke: new Stroke({
color: "white",
}),
}),
}),
});
vectorMap.addLayer(geoJsonLayer);
orthophotoMap.object3d.translateZ(+1500);
orthophotoMap.object3d.updateMatrixWorld();
vectorMap.object3d.translateZ(+2500);
vectorMap.object3d.updateMatrixWorld();
instance.view.camera.position.set(1832816, 5163527, 6121);
const controls = new MapControls(instance.view.camera, instance.domElement);
controls.target = extent.centerAsVector3();
controls.saveState();
controls.enableDamping = true;
controls.dampingFactor = 0.2;
instance.view.setControls(controls);
Inspector.attach("inspector", instance);
bindToggle("show-terrain", (v) => {
terrainMap.visible = v;
instance.notifyChange();
});
bindToggle("show-orthophoto", (v) => {
orthophotoMap.visible = v;
instance.notifyChange();
});
bindToggle("show-vector", (v) => {
vectorMap.visible = v;
instance.notifyChange();
});
bindSlider("terrain-opacity", (o) => {
terrainMap.opacity = o;
instance.notifyChange();
});
bindSlider("orthophoto-opacity", (o) => {
orthophotoMap.opacity = o;
instance.notifyChange();
});
bindSlider("vector-opacity", (o) => {
vectorMap.opacity = o;
instance.notifyChange();
});
bindSlider("vector-bg-opacity", (o) => {
vectorMap.backgroundOpacity = o;
instance.notifyChange(vectorMap);
});
<!doctype html>
<html lang="en">
<head>
<title>Stacking transparent maps</title>
<meta charset="UTF-8" />
<meta name="name" content="map_transparency_stack" />
<meta
name="description"
content="Illustrates how transparency in maps work."
/>
<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"
/>
<style>
#view 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="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">
<div class="mh-100 overflow-y-auto">
<!-- Vector map -->
<div class="card mb-1">
<div class="card-header">
<div class="form-check form-switch">
<input
class="form-check-input"
checked
type="checkbox"
role="switch"
id="show-vector"
autocomplete="off"
/>
<label class="form-check-label" for="show-vector"
>Vector map</label
>
</div>
</div>
<div class="card-body" id="vector-options">
<!-- Opacity -->
<label for="vector-opacity" class="form-label">Map opacity</label>
<div class="input-group">
<input
type="range"
min="0"
step="0.01"
max="1"
value="1"
class="form-range"
id="vector-opacity"
autocomplete="off"
/>
</div>
<!-- Opacity -->
<label for="vector-bg-opacity" class="form-label"
>Background opacity</label
>
<div class="input-group">
<input
type="range"
min="0"
step="0.01"
max="1"
value="0"
class="form-range"
id="vector-bg-opacity"
autocomplete="off"
/>
</div>
</div>
</div>
<!-- Orthophoto map -->
<div class="card mb-1">
<div class="card-header">
<div class="form-check form-switch">
<input
class="form-check-input"
checked
type="checkbox"
role="switch"
id="show-orthophoto"
autocomplete="off"
/>
<label class="form-check-label" for="show-orthophoto"
>Orthophoto map</label
>
</div>
</div>
<div class="card-body" id="orthophoto-options">
<!-- Opacity -->
<label for="orthophoto-opacity" class="form-label"
>Map opacity</label
>
<div class="input-group">
<input
type="range"
min="0"
step="0.01"
max="1"
value="1"
class="form-range"
id="orthophoto-opacity"
autocomplete="off"
/>
</div>
</div>
</div>
<!-- Terrain map -->
<div class="card mb-1">
<div class="card-header">
<div class="form-check form-switch">
<input
class="form-check-input"
checked
type="checkbox"
role="switch"
id="show-terrain"
autocomplete="off"
/>
<label class="form-check-label" for="show-terrain"
>Terrain map</label
>
</div>
</div>
<div class="card-body" id="terrain-options">
<!-- Opacity -->
<label for="terrain-opacity" class="form-label">Map opacity</label>
<div class="input-group">
<input
type="range"
min="0"
step="0.01"
max="1"
value="1"
class="form-range"
id="terrain-opacity"
autocomplete="off"
/>
</div>
</div>
</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": "map_transparency_stack",
"dependencies": {
"colormap": "^2.3.2",
"@giro3d/giro3d": "git+https://gitlab.com/giro3d/giro3d.git"
},
"devDependencies": {
"vite": "^3.2.3"
},
"scripts": {
"start": "vite",
"build": "vite build"
}
}