bizarre warping when rotating attached objects...

DoomiVox

This is a problem I've run into on and off for a few years that seems to just sometimes occur and sometimes not and the cause has been just invisible to me.

This is several objects linked to eachother in 3dsmax (much like a biped). Everything was working fine just before my last save and now when i try and rotate the arms I get this crazy skewing.

Does anyone know why this happens and how to fix it?

Thanks in advance.

GarageBay9

I've had that happen too... no idea exactly why.

It appears to be a form of gimbal lock, but that's not supposed to happen with the default TCB controllers.

Piflik

No Gimbal Lock...this happens, when you scaled the parent object non uniformly on Object Level. Don't ever do this...if you want to scale, go into Element or Vertex Subobject, select everything and scale that. If you absolutely have to scale on object level (don't know any reason for that...) then make sure the object is not a parent of any other object, scale it and apply a Reset X-Form immediately afterwards and collapse the model.

To fix it: Unlink the objects, apply Reset X-Form, collapse, rebuild the hierarchy.

DoomiVox

Thanks a bunch that did the trick! It's nice to finally understand what was going on.

Mark Dygert

Reset xform will do the trick but it can be like using a nuke to kill a fly. It will reorient the objects local pivot to the world, which for animators can be a bit disastrous.


Like Piflik said its a case of the scale transform data needing to be cleared out. You can do this by going to the Hirearchy tab > Reset > Scale

Doing it this way resets just the data that needs to be without effecting the local pivot. In theory you shouldn't need to unlink or relink anything.

mLichy

Yeah, I need to use that more often than re-setting all xforms. Although I usually planned it somehow so that my pivot could be recovered.

GarageBay9

Vig's right, reset scale should do the trick without blasting everything else.

If that doesn't work, try creating a helper obj, then matching it's position and orientation to the pivot of the object before you reset xform.

Then you can position / orientation match the pivot of the object you reset to the helper, restoring the original pivot. Little more cumbersome, but I have had reset scale occasionally not work.