VirtualCity animation misrender

[juj]

I don't know if this is a problem with the VirtualCity GLTF sample asset itself, or with the glTF Sample Viewer, though I noticed that the monorail renders incorrectly:

The monorail train carriages are all oriented the wrong way around, facing up instead of the expected direction of travel.

Another screencap:

[juj]

Same issue occurs with the cars on the street. They do not rotate towards the direction of travel, but have a constant orientation in one direction, so occassionally drive on the road facing sideways to the direction of the street lane:

[juj]

I suppose while at the topic, it makes sense to bring up one more obvious property about the model:

The scene has these animated white cubes flying around the city:

Given that they are so visually obvious/striking, at first I thought that was the test intent: i.e. "let's place some cubes to follow an animated trail" (maybe to test out a longer trail, or a looping animation trail? Not sure)

Though now when I eyeball these cubes closer, I see that they are not just cubes, but there are actually 3D airplane models embedded/intersecting the cubes:

that seems a bit off - I can't think of what the test intent would be here. Are the white cubes being visible maybe a bug, or intentional for some test reason?

Most assets have a nice README.md at the test root, that elaborate the test plan/test intent of the assets.

It would be good to have one for the VirtualCity asset as well at https://github.com/KhronosGroup/glTF-Sample-Assets/tree/main/Models/VirtualCity

I am not quite sure what differentiates this model from the other models in the test plan? One thing I see it has unique for it is that there are multiple cameras in the scene that are animated, to create a fly-by through the scene.

Although, there are a few issues with these cameras (and the models that these fly-by cameras are observing). E.g.:

• the camera is too close to the fly-by model, so the model clips the camera near plane,
• the camera trail goes too close to the ground plane, so the ground plane clips against the near plane of the camera,
• the fly-by airplane models don't seem to be watertight closed meshes, but feature floating geometry triangles on screen.

This is maybe one of the rougher test scenes in the repository. Feels a bit "messy".

[DRx3D]

As you have noted, this model has a number of issues. We are looking to replace the model while retaining some the important features (multiple moving cameras, complete virtual scene, etc.). So far no one within Khronos has had the time to work on a replacement. The latest think is to use some new features under development to make a showcase model for those features. If you (or anyone else) is interested in contributing a new model to the repository with these characteristics, please create an issue in the glTF-Sample-Assets repo for this asset and tag me (@DRx3D).