How to bend an IK chain the other way?

[cyrilrueg]

Hello,

How do you make an IK chain bend in the opposite direction? I tried using a Pole Vector, but it messes with the object's rotation on other axes. Thank you very much

https://we.tl/t-xQC298uxJr

[Dr. Sassi]

Hi cyrilrueg,

The key for the orientation is the Pole (Vector)
Example
CV4_2025_drs_25_CAik_01.c4d
Select the Pole Null and move it up and down (P.Y)

To create one:

More about this
https://help.maxon.net/c4d/2025/en-us/Default.htm#html/TCAIK-ID_TAGPROPERTIES.html#ID_CA_IK_TAG_SOLVER

All the best

[cyrilrueg]

Hi @Dr-Sassi, thanks for your reply. The problem is that the bracelet turns 180° when I add the pole. The movement of the IK is correct but the object is just turned upside down.

https://we.tl/t-ecuVwF1ApZ

[Dr. Sassi]

Hi cyrilrueg,

Thanks for the file.

Typically, the Pole Null is set somewhere; it must be moved to create the "plane" on which things should work, like the Dark green discs from the link in an earlier post. This needs to be done. Otherwise, the whole setup might flip at one point in an unwanted way. Positioning the pole needs testing based on the expected animation; sometimes adjustments are needed, which is why advanced rigs have an easy-to-access controller for that in the scene.

The simple way is to use the
IK-Tag>>Attribute Manager> Tag> Pole Vector> Axis or Twist option.

Your file
https://projectfiles.maxon.net/Cineversity_Forum_Support/2025_PROJECTS_DRS/20250312_CV4_2025_drs_25_CAip_11.c4d.zip

Documentation
https://help.maxon.net/c4d/2025/en-us/Default.htm#html/TCAIK-ID_TAGPROPERTIES.html#ID_CA_IK_TAG_POLE_TWIST

The alternative is to reset the Bind Pose, which is often much more work; however, the Pole needs to be placed properly.

All the best

[cyrilrueg]

Hi @Dr-Sassi, thank you for your quick reply! I'm sorry but I don't quite understand, in the file you gave me the bend is correct (shorter bracelet) but on the other (long bracelet) it moves in the wrong direction and with the pole it turns the object upside down

[Dr. Sassi]

Hi cyrilrueg, I haven't change the other part (Long), since you mentioned the Belt buckle is the problem.

Here are the setup and animated. On frame zero, you can delete the animation, without problems.

The Pole Needs to be adjusted to your needs, perhaps.

https://projectfiles.maxon.net/Cineversity_Forum_Support/2025_PROJECTS_DRS/20250313_CV4_2025_drs_25_CAip_12.c4d.zip

All the best

[cyrilrueg]

Hi @Dr-Sassi The problem is that the long bracelet object turns around when the pole is moved (see video attached)

https://we.tl/t-GrgnRh6ibJ

[Dr. Sassi]

Hi cyrilrueg,

That is not a problem; it is expected and wanted behavior.

The pole defines the orientation of the virtual disc, like the dark green ones mentioned above in the manual.
This disc is the key to solving the IK. Otherwise, the joints would just randomly move around in space.

My suggestion to move it up and down was to learn its influence on the solved IK chain.
The Pole, as mentioned, needs to be placed properly to make things work in a stable way.

Cheers