BoxAnimated clip durations do not match.

[donmccurdy]

1. Previewing the BoxAnimated model here: https://gltf-viewer.donmccurdy.com/#model=https://raw.githubusercontent.com/KhronosGroup/glTF-Sample-Models/master/2.0/BoxAnimated/glTF/BoxAnimated.gltf
2. Open the "Animation" tab and press "playAll". (see Merge animations in most samples, add sample using multiple animations correctly #108)

After pressing playAll, the two clips (position and rotation) line up for the first runthrough, but their durations are different, so after this they stop lining up. Same issue occurs in the BabylonJS sandbox. In the console I find:

I believe this has the same underlying cause as #108, namely that these two clips should have been a single animations entry, inherently with the same length, but do not.

[pjcozzi]

Sounds like a COLLADA2GLTF issue or an issue with the COLLADA exporter. I'm pretty sure this model was authored with Modo.

[pjcozzi]

@likangning93 can you see if this model has the same animation issue you were having?

Then perhaps you can discuss with @sbtron @bghgary and others here.

[likangning93]

@pjcozzi not quite the same problem.

This is two separate animations looping asynchronously and slipping, but the problem I was discussing with @sbtron and @bghgary is what to do when looping separate channels within one animation. Babylon "wraps" when time is outside a channel's given keyframes and Three.js holds the nearest keyframe, while Cesium can do either but defaults to holding.

[likangning93]

But for what it's worth, I also think the box's animations should actually be separate channels in one animation, and if there was a second animation it'd have the smaller box do something completely different like *gasp* rotate along a different axis.

[pjcozzi]

Moved spec discussion to the glTF repo: KhronosGroup/glTF#1179