To create an animation blend from FK to IK
Select your joint chain and IK handle.
In the IK Solver Attributes, drag the Ik Blend slider to 0.000.
The animation mode is now set to pure FK.

Set a key (default hotkey: s key).
Deselect the IK handle, select a joint in your joint chain, and set a key once more.
You will now be keying the joint (for FK)-not the handle (for IK).

Drag the current time indicator along the timeline and translate or rotate the joint.
Set a key.
Repeat steps 5 and 6 until you complete the FK portion of your animation.
Once you set the last FK key, deselect the joint and select the IK handle of your joint chain.
Verify that the Ik Blend slider is at 0.000, and set a key.
Drag the Ik Blend slider to 1.000 and set a key on the handle.
Since there is no period of animation between the last pure FK key and the first pure IK key, the FK animation switches to IK instantly (without a blend).

The animation mode is now set to pure IK.

Note

When there is a period of animation between a pure FK key and a pure IK key, it is interpolated by the IK Solver. The interpolated animation then appears as Ik Blend values between 0.000 and 1.000.



Example of IK/FK blending
Blending the FK animation of a swinging arm with the IK animation of a waving arm.


A simple animation of a swinging arm during a walk cycle is created by selecting the root of an arm's joint chain (the shoulder joint), rotating it along the Z axis, and then setting keys for the joint. This produces a rudimentary FK animation.


This FK animation sequence is blended with the directed motion of the arm waving by setting keys on the IK handle and the shoulder joint at the end of the FK animation, moving the timeline indicator to create a blend region, changing the Ik Blend value to 1.000 (pure IK), and once again setting keys on the shoulder joint and IK handle. In the area between the pure FK and IK animation-the blend region, the IK Solver interpolates the animation from 0.000 to 1.000.


Pure IK animation is reached once the Ik Blend value is 1.000. The IK handle is then translated and rotated while setting keys, to produce the animation of the arm waving.

When the animation of the waving arm is complete, the animation is set back (using another blend region and changing the Ik Blend value to 0.000) to pure FK. The resulting animation resembles a swinging arm (FK) that rises into a wave (IK) and then descends back into a swinging motion (return