feat(assets): publish reusable area packages

examples/asset-package-resolver.js

@@ -0,0 +1,13 @@
+"use strict";
+
+function resolveAsset(manifestUrl, manifest, id = "main") {
+  const asset = manifest.assets.find((candidate) => candidate.id === id);
+  if (!asset) throw new Error(`Unknown asset '${id}'`);
+  return new URL(asset.uri, manifestUrl).href;
+}
+
+function placement(manifest) {
+  return { ...manifest.placement, coordinateSystem: manifest.coordinateSystem };
+}
+
+module.exports = { resolveAsset, placement };

examples/cesium-asset-package.js

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+"use strict";
+
+const { resolveAsset, placement } = require("./asset-package-resolver");
+
+async function loadPackage(viewer, manifestUrl, assetId = "main") {
+  const manifest = await fetch(manifestUrl).then((response) => {
+    if (!response.ok) throw new Error(`Could not load manifest: ${response.status}`);
+    return response.json();
+  });
+  const p = placement(manifest);
+  const origin = Cesium.Cartesian3.fromDegrees(p.longitude, p.latitude, p.height);
+  const enu = Cesium.Transforms.eastNorthUpToFixedFrame(origin);
+  const rotation = Cesium.Matrix3.fromRotationZ(Cesium.Math.toRadians(p.headingCorrectionDegrees));
+  const modelMatrix = Cesium.Matrix4.multiplyByMatrix3(enu, rotation, new Cesium.Matrix4());
+  const model = await Cesium.Model.fromGltfAsync({ url: resolveAsset(manifestUrl, manifest, assetId), modelMatrix });
+  viewer.scene.primitives.add(model);
+  return { manifest, model, placement: p };
+}
+
+module.exports = { loadPackage };

examples/three-asset-package.js

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+"use strict";
+
+const { resolveAsset, placement } = require("./asset-package-resolver");
+
+async function loadPackage(loader, manifestUrl, assetId = "main", handoffEnuPlacement) {
+  const manifest = await fetch(manifestUrl).then((response) => {
+    if (!response.ok) throw new Error(`Could not load manifest: ${response.status}`);
+    return response.json();
+  });
+  const scene = await loader.loadAsync(resolveAsset(manifestUrl, manifest, assetId));
+  // Three.js does not georeference local ENU itself; the embedding host owns it.
+  const enuPlacement = placement(manifest);
+  if (handoffEnuPlacement) handoffEnuPlacement(enuPlacement, scene.scene);
+  return { manifest, scene: scene.scene, placement: enuPlacement };
+}
+
+module.exports = { loadPackage };