When you add full body IK to your character, a FK skeleton and a set of FBIK effectors are created, and your character’s original skeleton becomes its input skeleton. For FBIK to work, the hikSolver requires both the input and FK skeletons.
In the scene view, the input skeleton appears brown and the FK skeleton appears dark blue. To make the FK skeleton visible in the scene view, select Skeleton > Full Body IK > Show FBIK FK Skeleton or Hide FBIK FK Skeleton.
During interaction, the hikSolver synchronizes your FK skeleton and the input skeleton driven by the FBIK effectors. Also, advanced FBIK attributes like Pull and Stiffness are not taken into account during interaction. See hikHandle.
During playback, your FK and input skeletons contribute to the resulting FBIK animation, but they are no longer synchronized.
When posing with FBIK, you can transform the joints of your character’s input skeleton to create joint-level poses. This is similar to posing with regular FK in Maya. See Posing skeletons.
When animating with FBIK, you can key the joints of the your character’s input skeleton and their FBIK effectors to create FK animation. Any keys you set on the input skeleton are not actually placed there, but are instead placed on the FK skeleton.
When playing back your FBIK animation, the input skeleton shows the resulting FBIK animation in the scene view, similar to the blend skeleton when blending IK/FK animation. See IK/FK blending.
The input skeleton is also used to bind your character’s skin.
When posing with FBIK, you do not transform the joints in the FK skeleton, but instead you manipulate the joints in the input skeleton to create FK-type poses.
When animating with FBIK, you do not key the joints of your FK skeleton, but instead you key the joints of your input skeleton and their FBIK effectors to create FK animation. However, the keys that you set on the input skeleton are placed on the FK skeleton.
When playing back your FBIK animation, you can show the FK skeleton to view the differences between your character’s input and FK skeleton’s poses.
