Add example featuring numpytiles

examples/numpytile.html

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+---
+layout: example.html
+title: Rendering 16-bit NumpyTiles
+shortdesc: Renders a multi-byte depth source image directly using webGL.
+docs: >
+  Use the NumpyTile format to render multibyte raster data.
+tags: "numpytiles"
+---
+<div id="map" class="map"></div>
+
+<div>
+  <h5>Adjust colors</h5>
+  <ul>
+    <li><b>Min:</b> <input type="range" min="1000" max="10000" id="color-floor"/></li>
+    <li><b>Max:</b> <input type="range" min="10000" max="50000" id="color-ceil"/></li>
+  </ul>
+
+</div>
+
+<script type="text/javascript" src="https://unpkg.com/@planet/ol-numpytiles@2.0.2/umd/NumpyLoader.js"></script>

examples/numpytile.js

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+import Map from '../src/ol/Map.js';
+import TileLayer from '../src/ol/layer/WebGLTile.js';
+import View from '../src/ol/View.js';
+
+import DataTileSource from '../src/ol/source/DataTile.js';
+import OsmSource from '../src/ol/source/OSM.js';
+import {fromLonLat} from '../src/ol/proj.js';
+
+// 16-bit COG
+// Which will be served as NumpyTiles.
+const COG =
+  'https://storage.googleapis.com/open-cogs/stac-examples/20201211_223832_CS2_analytic.tif';
+
+function numpyTileLoader(z, x, y) {
+  const url = `https://api.cogeo.xyz/cog/tiles/WebMercatorQuad/${z}/${x}/${y}@1x?format=npy&url=${encodeURIComponent(
+    COG
+  )}`;
+
+  return fetch(url)
+    .then((r) => r.arrayBuffer())
+    .then((buffer) => NumpyLoader.fromArrayBuffer(buffer)) // eslint-disable-line no-undef
+    .then((numpyData) => {
+      // flatten the numpy data
+      const dataTile = new Float32Array(256 * 256 * 5);
+      const bandSize = 256 * 256;
+      for (let x = 0; x < 256; x++) {
+        for (let y = 0; y < 256; y++) {
+          const px = x + y * 256;
+          dataTile[px * 5 + 0] = numpyData.data[y * 256 + x];
+          dataTile[px * 5 + 1] = numpyData.data[bandSize + y * 256 + x];
+          dataTile[px * 5 + 2] = numpyData.data[bandSize * 2 + y * 256 + x];
+          dataTile[px * 5 + 3] = numpyData.data[bandSize * 3 + y * 256 + x];
+          dataTile[px * 5 + 4] =
+            numpyData.data[bandSize * 4 + y * 256 + x] > 0 ? 1.0 : 0;
+        }
+      }
+      return dataTile;
+    });
+}
+
+const interpolateBand = (bandIdx) => [
+  'interpolate',
+  ['linear'],
+  ['band', bandIdx],
+  ['var', 'bMin'],
+  0,
+  ['var', 'bMax'],
+  1.0,
+];
+
+const createNumpyStyle = (bandMin, bandMax) => ({
+  color: [
+    'array',
+    interpolateBand(3),
+    interpolateBand(2),
+    interpolateBand(1),
+    ['band', 5],
+  ],
+  variables: {
+    'bMin': bandMin,
+    'bMax': bandMax,
+  },
+});
+
+const numpyLayer = new TileLayer({
+  style: createNumpyStyle(3000, 18000),
+  source: new DataTileSource({
+    loader: numpyTileLoader,
+    bandCount: 5,
+  }),
+});
+
+const map = new Map({
+  target: 'map',
+  layers: [
+    new TileLayer({
+      source: new OsmSource(),
+    }),
+    numpyLayer,
+  ],
+  view: new View({
+    center: fromLonLat([172.933, 1.3567]),
+    zoom: 15,
+  }),
+});
+
+const configureInputs = () => {
+  const colorFloor = document.getElementById('color-floor');
+  const colorCeil = document.getElementById('color-ceil');
+
+  colorFloor.addEventListener('input', (evt) => {
+    numpyLayer.updateStyleVariables({
+      'bMin': parseFloat(evt.target.value),
+      'bMax': parseFloat(colorCeil.value),
+    });
+  });
+
+  colorCeil.addEventListener('input', (evt) => {
+    numpyLayer.updateStyleVariables({
+      'bMin': parseFloat(colorFloor.value),
+      'bMax': parseFloat(evt.target.value),
+    });
+  });
+};
+configureInputs();