How to ik double and triple bone systems?

[ACCCC]

I'm in the process of learning to create ik rigs and i encountered a problem with certain skeleton types.

An easy to understand example for a triple bone leg would be the following hierarchy:

Root

-Hip (Main Bone)

-Hip Push Bone (Push Bone)

--Hip Part 1 (Twist Bone)

---Hip Part 2 (Twist Bone)

----Knee (Main Bone)

-----Knee Push Bone (Push Bone)

-----Knee Part 1 (Twist Bone)

------Knee Part 2 (Twist Bone)

-------Ankle (Main Bone)

The problem with this setup is that a normal IK Chain from the "Hip" to the "Ankle" would cause the whole Hierarchy to bend even though the actual bones that should bend are the Hip, Knee and Ankle Bones.

How do i rig something like this? Is there a way to exclude bones from a IK Chain?

[ads_royje · Accepted solution]

Hi @ACCCC,

The IK system will be created using the Parent - Child relation, there is no options to by-pass a child in the hierarchy down to the last child (where the IK goal is created)

The hierarchy should look like this :

Root

-Hip (Main Bone)

-Hip Push Bone (Push Bone)

--Hip Part 1 (Twist Bone)

--Hip Part 2 (Twist Bone)

--Knee (Main Bone)

--Knee Push Bone (Push Bone)

--Knee Part 1 (Twist Bone)

--Knee Part 2 (Twist Bone)

---Ankle (Main Bone)

 where the bones between the Hips (Thigh) -> Knee -> Ankle are not Parent of any bones used by the IK system.

. Ankle child of Knee

. Knee child of Hip (Thigh)

. Hip's Twist bones (part 1 + 2) child of Hips (thigh).

. Knee's Twist bones (part 1 + 2) child of Knee.

Then you can set the Twist Bones with their controllers to twist as you like.

The IK System works best with 2 bending bones (3 bones total, where the 3rd Bone is where the IK goal is created).

I hope this can help 🙂