.. _IK:

=================
Inverse kinematic
=================

The IK animation type uses a list of targets (trackers) and an IK solver to animate the avatar. 

The Unity Animation Rigging system available by default, a second animation system is available for projects containing the FinalIK package.

To define the number of trackers and the tracked objects, see :ref:`IKConfig`.

Unity Animation rigging
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The Unity Animation Rigging system is available by default. It uses Unity's `Animation rigging package <https://docs.unity3d.com/Packages/com.unity.animation.rigging@1.1/manual/index.html>`_ as IK solver for the limbs of the avatar.

The Animation rigging package is set as a dependency in the Avatar Ready package, no action is needed to add it to the project.

FinalIK
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For users having the `FinalIK package <https://assetstore.unity.com/packages/tools/animation/final-ik-14290>`_, a second animation system is provided using FinalIK as IK solver.
The FinalIK package is an external asset that provider an enhanced inverse kinematic solver. It is available on the Unity Asset store and requires a license.

You will need to manually add the package to your unity project.

Once the FinalIK package has been added to the Unity project, the AvatarReady package should automatically detect its presence in the project and update accordingly.

The FinalIK package offers a better IK solver that applies to the full body of the avatars.
This package also provides a locomotion solver to animate the legs of the avatar.