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 } 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';
// # Planar (EPSG:3946) viewer
// Defines projection that we will use (taken from https://epsg.io/3946, Proj4js section)
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',
);
// Defines geographic extent: CRS, min/max X, min/max Y
const extent = new Extent('EPSG:3946', 1837816.94334, 1847692.32501, 5170036.4587, 5178412.82698);
// `viewerDiv` will contain Giro3D' rendering area (the canvas element)
const viewerDiv = document.getElementById('viewerDiv');
// Creates the Giro3D instance
const instance = new Instance(viewerDiv, {
crs: 'EPSG:3946',
renderer: {
clearColor: false,
},
});
const terrainMap = new Map('terrain', { extent, doubleSided: true, 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('orthophoto', { extent, doubleSided: true });
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('geojson', { extent, doubleSided: true, backgroundOpacity: 0 });
instance.add(vectorMap);
const geoJsonLayer = new ColorLayer({
name: 'geojson',
extent,
source: new VectorSource({
data: '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();
// Sets the camera position
instance.camera.camera3D.position.set(1832816, 5163527, 6121);
// Creates controls
const controls = new MapControls(instance.camera.camera3D, instance.domElement);
// Then looks at extent's center
controls.target = extent.centerAsVector3();
controls.saveState();
controls.enableDamping = true;
controls.dampingFactor = 0.2;
instance.useTHREEControls(controls);
Inspector.attach(document.getElementById('panelDiv'), instance);
// Bind events
function bindToggle(id, callback) {
const toggle = document.getElementById(id);
toggle.oninput = () => {
const state = toggle.checked;
callback(state);
instance.notifyChange();
};
}
function bindSlider(id, callback) {
const slider = document.getElementById(id);
slider.oninput = function oninput() {
callback(slider.valueAsNumber);
instance.notifyChange();
};
}
bindToggle('show-terrain', v => {
terrainMap.visible = v;
});
bindToggle('show-orthophoto', v => {
orthophotoMap.visible = v;
});
bindToggle('show-vector', v => {
vectorMap.visible = v;
});
bindSlider('terrain-opacity', o => {
terrainMap.opacity = o;
});
bindSlider('orthophoto-opacity', o => {
orthophotoMap.opacity = o;
});
bindSlider('vector-opacity', o => {
vectorMap.opacity = o;
});
bindSlider('vector-bg-opacity', o => {
vectorMap.materialOptions.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>
#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" class="m-0 p-0 w-100 h-100"></div>
<div id="panelDiv" 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"
}
}