Return first geometryBuffer if no best batch found

- Check parent resource is defined

CHANGES.md

@@ -17,6 +17,7 @@
 - Added multiscattering terms to diffuse BRDF in image-based lighting. [#12118](https://github.com/CesiumGS/cesium/pull/12118)
 - Fixed CallbackProperty type not being present on entity position. [#12120](https://github.com/CesiumGS/cesium/pull/12120)
 - Additional TypeScript types export in package.json to assist some project configurations using Cesium. [#12122](https://github.com/CesiumGS/cesium/pull/12122)
+- Use first geometryBuffer if no best match found in I3SNode [#12132](https://github.com/CesiumGS/cesium/pull/12132)
 
 ##### Breaking Changes :mega:
 

CONTRIBUTORS.md

@@ -394,3 +394,4 @@ See [CONTRIBUTING.md](CONTRIBUTING.md) for details on how to contribute to Cesiu
 - [Vladislav Yunev](https://github.com/YunVlad)
 - [Levi Montgomery](https://github.com/Levi-Montgomery)
 - [Brandon Berisford](https://github.com/BeyondBelief96)
+- [Lawrence Owen](https://github.com/ljowen)

packages/engine/Source/Scene/I3SLayer.js

@@ -291,9 +291,15 @@ I3SLayer.prototype._findBestGeometryBuffers = function (
         };
       }
     }
+    // If no match found return first geometryBuffer
+    if (defined(geometryDefinition[0])) {
+      return {
+        bufferIndex: 0,
+        definition: geometryDefinition,
+        geometryBufferInfo: geometryDefinition[0],
+      };
+    }
   }
-
-  return 0;
 };
 
 /**

packages/engine/Source/Scene/I3SNode.js

@@ -219,7 +219,7 @@ I3SNode.prototype.load = async function () {
     const uriIndex = node.mesh.geometry.resource;
     uri = `../${uriIndex}/`;
   }
-  if (defined(uri)) {
+  if (defined(uri) && defined(that._parent.resource)) {
     that._resource = that._parent.resource.getDerivedResource({ url: uri });
   }