Is Reaction Manager completely useless with CAT because fbx-export cannot be trusted not to flip?! (problem)

[oyvind3BPMJ]

So I've found an issue with CAT/reaction manager which frustrates me greatly.

It seems exporting to FBX causes weird, flipping animation (as seen in unreal engine) 

I made a headswitch with reaction manager,  enabling the head to orient automatically to any of 5 modes: head orients same as 1) neck, 2) chest, 3) pelvis 4) world or 5) looks at a controller.

It looks good in 3ds max 2022. But after exporting, I notice that anything which uses reaction manager (driven by the ExposeTm node which exposes the CAT bones) is really buggy and weirdly in export.

FBX export as seen in unreal:

In this gif, you see a creature whose face flips around in impossible ways (I say impossible, because the head bone which flips the face is the parent of all the other headbones (horns, eyes, jaws, etc), so it should be impossible for these child bones to not follow the head as it twists - yet that is exactly what happens)

 I've tried countless things to get reaction manager to work consistently.

I was hoping someone who has actually used reaction manager successfully with CAT could help me understand what might be causing this issue?

Below I'll paste my method of creating this head switch:

If the animator moves the switch bone, the following should happen instantly:

1. The ExposeTM helper makes the movement of the switch bone to be accessible to reaction manager
2. Reaction manager, with exposeTM as driver, changes the weights of the orient constraint on a point helper, so it aligns with one of the headspaces, e.g. torso.
3. The body has several point helpers parented under controllers to be used as targets for the orient constraint. In this case: Last neck bone, chest bone, pelvis bone, world, and another one the neck bone which is lookAt constrained to look at a CAT bone.
4. The actual head bone’s orient constraint (in setup mode) rotates to match the point helper we used in step 2.
5. In anim mode the head follows a new headspace, but it can also be offset rotationally on its own.
   
   

[paulneale]

Expose TM really isn't the problem so much as you are using Quaternion values which don't wind up. Why are you exactly using the EXTM node in this case?

[oyvind3BPMJ]

So long story short, I ended up finding out that the culprit of all my
troubles was not Reaction manager, but rather a CAT spine which caused
awful FBX exports, yet the problem could not be seen untill exporting. So I
re-rigged to not use a CAT spine.

The expose node was required to make a CAT bone be the master (turn on/off)
of the rig feature which went haywire

IIRC, without the expose node, I couldn’t get the rig feature to work on
separate animations on separate CAT layers. IIRC CAT bones did not work
directly with Reaction manager

Sorry if explanation is insufficient, its been a while

Øyvind