Animation inside Blender stops working after three.js export (r71 dev)

[fredleefarr]

As a test case, I've animated the default Blender cube along the z-axis for 20 frames. In the Dope Sheet, it looks like this:

Then, I've selected the armature and the cube, and exported with the following settings:

If I then try to play the animation again, red lines appear in the dope sheet, and the animation doesn't play:

In the Dope Sheet, I've tried selecting Channel > Revive Disabled F-Curves, which makes the red lines go away but doesn't fix the issue.

[repsac]

Looks like a disconnection between the curve and the mesh. Probably because a temp mesh is created during the export process.

[repsac]

I can recreate this easily enough.

which makes the red lines go away but doesn't fix the issue.

Can you clarify? Do you mean the animation is still broken or that it's not an actual solution to this issue (which I would agree with). If the animation is fixed after doing this then all I may have to do is add the one-liner that is called when Channel > Revive Disabled F-Curves is invoked.

[repsac]

OK so I get the red lines but my animation still plays. In fact when I scrub the animation the red lines go away. Then if I deselect and then reselect the armature they return.

I tried scripting the Revive Disabled F-Curves and it seems to have no effect.

[repsac]

Still not making a lot of sense. The original geometry and its relation to the armature appears to be preserved. The export geometry is replaced with the original. Same logic that has always been in place. This does lead me to consider something that is common in CG pipelines when performing conversions, exports, or publishes which is save the current scene to a working file (commonly $TMPDIR) and upon completion (success or failure) re-open the original scene.

Normally export artifacts in a scene aren't an issue with my work flow because I run lots of my exports in a batch mode that opens the scenes, runs the export, and closes without saving. Animation exports are a unique pain because the context changes that have to occur don't work in batch mode (at least I haven't figured out an alternate way to do this without tripping over the UI contextual awareness), which isn't pipeline friendly if you want to dispatch your exports to the farm/cloud.

Going to now seriously considering implementing this as a feature (boolean parameter a user could disable). This will mean users should be proactively saving their scenes (which they should be while working in production!) before running the export because an edit would get lost when the scene re-opens.

[fredleefarr]

OK, thanks for looking into this - I just stumbled upon the issue when experimenting with animation exports. Can easily re-open the Blender file after export as a work-around. Let me know if you need anything tested further at this end.

[repsac]

I have lots of people doing animation exports and haven't reported the animation actually breaking (that I could not recreate) but then again something not happening is different from something not being reported. I can recreate the red lines but it isn't exactly clear why Blender displays them. Especially when I scrub the animation and they go away and only redraw when I reselect the armature.

[Mugen87]

The JSON Blender exporter has been removed with R93 (#14117).

Also see: https://threejs.org/docs/#manual/introduction/Loading-3D-models