Leg IK node and FK/IK joints

Hi, I want to use a Leg IK node in my anim graph but I am not sure why it requires both FK and IK joints. I actually have no IK specific joints in my skeleton, why would I need any? It seems the knee twist correction only works where both FK and IK joints are defined but I don’t understand why.

The LegIK node requires your skeleton to have IK feet bones to use as bone targets. The FK bone will be your normal foot bone.

Having just looked at the free Paragon Greystone asset, it looks like the Leg IK node will try to position the FK to the IK bone. Before calling the LegIK node you would set the left/right foot IK bone position using Transform(Modify)Bone from a line trace or similar. Then for the right foot you would normally select “foot_r” for the FK bone, and then “ik_foot_r” for the IK bone. The LegIK node will then try to adjust the feet accordingly.