Solved Python Tag Priority Problem


I'm trying to rig using the Python tag but having a priority problem. I already tried shifting the priority numbers but it seems to be something else.

There is only two tags that are at work the Python tag and the IK Tag

You can see an illustration video of the problem here:
illustration video

For the illustration file, you can check it here:
illustration file

Thank you for looking at the problem

Hi @bentraje this is, unfortunately, a know Cinema 4D limitation.

But I do have a few things to mention:
In a TagData and a Python Scripting tag you are not allowed to modify the scene (so calling AddUndo,EndUndo, and EventAdd) from this threaded context is really wrong and can lead to undefined behavior (and it's actually doing nothing).

Moreover, if you move your python tag to the lowerArm_bendy_L_con then the issue is limited (of course you still need to press CLTR+A after an Undo if you move the lowerArm_bendy_L_con).

Finally, if you move the lowerArm_bendy_L_con_grp while the python tag is moved to lowerArm_bendy_L_con, it's working nicely (and could be a workaround)


Hi @m_adam

Thanks for the response. I'm not quite sure what you mean by

RE: a know Cinema4D limitation"
Is it the priority system or the python tag itself?

RE: Finally, if you move the lowerArm_bendy_L_con_grp. . .
I'm not sure. By any chance, do you mean something like this?

I'm not sure if I got it right since it still lags a little bit.

Sorry for not being enough clear.

This is a Cinema 4D limitation of the priority/Viewport system.

Yes, you get it correctly. I know you still need to click on "A" or CLTR+A in order to redraw the view. But this as a said a Priority/Viewport issue that can't be fixed in your end.

My last point is that if you move the null (lowerArm_bendy_L_con_grp) on your last video it's working. So maybe you can hide the spline and display the null as a Rectangle, so you will only interact with this Null (note that it's also faster to draw null than Spline).


Thanks @m_adam for the reply.

RE: This is a Cinema 4D limitation of the priority/Viewport system.
Gotcha. I'm guessing this is a python tag specific priority system too.

The reason is the file above is a stripped down version of the Character Object with the Xpresso changed to python tag.
And in the Character Object, there are no priority/viewport lag.

RE: you can hide the spline and display the null as a Rectangle,
Thanks for the suggestion but I can't. The reason is I'll toggle an effect of a bendy arm and no bendy. As such, I need a buffer where a control is with bendy and another not.

Same thing IK and FK switch mechanism.

Apply the change I mentioned and apply the correct priority (same than Xpresso) fixed the issue but in some case.



Works as expected. Thank you @m_adam for getting back to me.

Have a great day ahead!