Transparent canvas background

A canvas with a transparent background.

You can render Giro3D's scene on a transparent background, using the appropriate options in the Instance constructor.

index.js

import colormap from "colormap";

import { Color, DoubleSide } from "three";
import { MapControls } from "three/examples/jsm/controls/MapControls.js";

import XYZ from "ol/source/XYZ.js";

import Extent from "@giro3d/giro3d/core/geographic/Extent.js";
import Instance from "@giro3d/giro3d/core/Instance.js";
import ElevationLayer from "@giro3d/giro3d/core/layer/ElevationLayer.js";
import Map from "@giro3d/giro3d/entities/Map.js";
import GeoTIFFFormat from "@giro3d/giro3d/formats/GeoTIFFFormat.js";
import ColorMap, { ColorMapMode } from "@giro3d/giro3d/core/layer/ColorMap.js";
import TiledImageSource from "@giro3d/giro3d/sources/TiledImageSource.js";
import Inspector from "@giro3d/giro3d/gui/Inspector.js";

const x = -13602000;
const y = 5812000;
const halfWidth = 2500;

const extent = new Extent(
  "EPSG:3857",
  x - halfWidth,
  x + halfWidth,
  y - halfWidth,
  y + halfWidth,
);

const instance = new Instance({
  target: "view",
  crs: extent.crs,
  backgroundColor: null,
});

const map = new Map({
  extent,
  hillshading: true,
  side: DoubleSide,
  backgroundColor: "white",
});

instance.add(map);

const source = new TiledImageSource({
  source: new XYZ({
    minZoom: 10,
    maxZoom: 16,
    url: "https://3d.oslandia.com/dem/MtStHelens-tiles/{z}/{x}/{y}.tif",
  }),
  format: new GeoTIFFFormat(),
});

const floor = 1100;
const ceiling = 2500;

const values = colormap({ colormap: "viridis", nshades: 256 });
const colors = values.map((v) => new Color(v));

const dem = new ElevationLayer({
  name: "dem",
  source,
  extent,
  colorMap: new ColorMap(colors, floor, ceiling, ColorMapMode.Elevation),
});

map.addLayer(dem);

instance.view.camera.position.set(-13594700, 5819700, 7300);

const controls = new MapControls(instance.view.camera, instance.domElement);

controls.target.set(-13603000, 5811000, 0);

instance.view.setControls(controls);

instance.notifyChange();

Inspector.attach("inspector", instance);

index.html

<!doctype html>
<html lang="en">
  <head>
    <title>Transparent canvas background</title>
    <meta charset="UTF-8" />
    <meta name="name" content="transparent_background" />
    <meta
      name="description"
      content="A canvas with a transparent background."
    />
    <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"
    />

    <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>

    <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": "transparent_background",
    "dependencies": {
        "colormap": "^2.3.2",
        "@giro3d/giro3d": "0.41.0"
    },
    "devDependencies": {
        "vite": "^3.2.3"
    },
    "scripts": {
        "start": "vite",
        "build": "vite build"
    }
}