Why does SNAP TO IK change the legs position in MHX?

[bouich jules]

Hi,

I did download the last commit version of diffeo and MHX

the issue is same:

https://streamable.com/mkbuwp

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How to reproduce:

1. import manually a G9
2. import a pose
3. snap ik

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The legs position will change, please also note that snapping in fk again will totally deform the position.

Please if you can have a look at this issue, i believe it’s an extremely serious issue for MHX.

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Thank you so much!

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[bouich jules]

Better results when turn off “ POLE TARGET” that is supposed make fk/ik better actually it make it worst.

[Thomas Larsson]

Apparently the problem is that the plugin imposes rotation locks after bones have been snapped. That has been disabled in the latest commit. However, now the problem is that we may be stuck with non-zero rotations for locked channels. I will need to come back to this.

[Maneki]

The same happens to simple IK. In a kneeling position with locks and rotation limits deactivated, the legs always either bend outwards or inwards. I assume that’s not intended?

[Alessandro Padovani]

As I understand it. In general IK is not compatible with FK limits, in that a IK chain may push the bones outside those limits. So it is a good habit to disable limits when we work with IK. On the other side locks shouldn’t be an issue, in that the IK chain and the FK bones can/should have the same locks. Specifically the FK bones should inherit the IK locks, not vice versa, because IK locks are needed for IK stability. For example shins and forearms only bend with IK, while FK may allow other movements as well.

[Alessandro Padovani]

Duplicate of #1927.