glTF 2.0 models cause crash when skin does not explicitly point to a skeleton.

[sanjeetsuhag]

glTF 2.0 allows for models with skins that don't directly refer to a skeleton. Cesium_Man.glb is validated by glTF Validator and is rendered in Babylon and Three.js, but causes an error in Cesium.

The issue lies in Source/Model.js where it's assumed that the skin will have a skeleton directly associated with it.

[emackey]

This is a fairly substantial discrepancy between Cesium and glTF's skinning specification. The spec explicitly says that the skeleton is optional, but Cesium treats it as required.

I'm by no means a skinning expert, but it appears very difficult with the current glTF-Blender-IO project to export any kind of skinned mesh from Blender and get it to load correctly in Cesium, even if the model validates correctly and loads into Babylon and ThreeJS without issue.

All of the "working in Cesium" skinned models that I know of appear to have come through COLLADA2GLTF, not Blender.

[OmarShehata]

Is the same issue as #8175 ?

[emackey]

Oh yeah, I had deja-vu but I couldn't find that one, thanks.