Marco Hutter

It may be worth noting that these properties are actually not defined in the `material`, for example, but at https://github.com/KhronosGroup/glTF/blob/082d5a98f479c37dff18767982d1431fc6c014fd/specification/2.0/schema/glTFProperty.schema.json#L6 (which `material` is ""inheriting"" from, as far as one can...

I think that _some_ requirement for the 'version' field might be useful. E.g. requiring it to have the semantic versioning pattern. For example, glTF [requires](https://registry.khronos.org/glTF/specs/2.0/glTF-2.0.html#reference-asset) it to be `.`, **but**...

The sample from the glTF-Sample-Assets is interesting, but that being "all over the place" is the result of not having any rules (and no `generatorVersion` property to begin with). Looking...

Maybe to clarify: I think that a dedicated `generatorVersion` _would_ make sense, but only if there is some requirement for the pattern of that field (preferably SemVer-like, so that clients...

I'd need _much_ more time to understand what's going on there. (Sure, it will eventually boil down to something simple, but for now, it is just swizzling some quaternion components,...

I had another short look at this. And I created a test data set to _dedicatedly_ test the rotations:  (Here, rendered in BabylonJS) It contains, from bottom to top...

I'm not sure if spherical harmonics with degree > 0 are supposed to be supported in the current state. But here's some test data: [Cesium Splats SH 2025-07-02.zip](https://github.com/user-attachments/files/21025673/Cesium.Splats.SH.2025-07-02.zip) (With PLY,...

The issue about the spherical harmonics might be caused by https://github.com/drumath2237/spz-loader/blob/4032056c1d2628ae9cf89dc0c2233cc15381e8ee/packages/core/lib/spz-wasm/gaussianCloud.ts#L48 - to be investigated.

(EDITED:) From my understanding, - The [`spz-loader` library calls `rotate180DegAboutX`](https://github.com/drumath2237/spz-loader/blob/4032056c1d2628ae9cf89dc0c2233cc15381e8ee/packages/core/lib/spz-wasm/main.cpp#L23) on the gaussian cloud - The [`GltfSpzLoader`](https://github.com/CesiumGS/cesium/blob/82b2c07064997e5d197fb71293de2320ad947284/packages/engine/Source/Scene/GltfSpzLoader.js#L153) does not account for that - The [`PrimitiveLoadPlan`](https://github.com/CesiumGS/cesium/blob/82b2c07064997e5d197fb71293de2320ad947284/packages/engine/Source/Scene/PrimitiveLoadPlan.js#L261) _tries_ to convert this back...

When the same `glb` content (with SPZ) is referred to by _two_ tiles with different `transform`, then the positions of the splats are all messed up. Apparently, there is some...