Blend IK and FK animation

This topic assumes you're using the Animation menu set (press F4).

Note: If you want to rotate or key individual joints in a joint chain that already have IK animation, turn on Ik Fk Control in the ikHandle attributes.

To create an animation blend from FK to IK

  1. Select the IK handle of the IK chain that you want to animate with FK.
  2. In the IK Solver Attributes, drag the Ik Blend slider to 0.000.

    The animation mode is now set to pure FK.

  3. Select Key > IK/FK Keys > Set IK/FK Key.

    All the joints in the IK chain and the IK handle are keyed.

    You will now be keying the joints (FK)—not the handle (IK).

  4. Deselect the IK handle.
  5. Select a joint in the IK chain, drag the current time indicator along the Time Slider and rotate the joint.
  6. Set a key.
  7. Repeat steps 5 and 6 until you complete the FK portion of your animation.
  8. Once you set the last FK key, deselect the current joint and select the IK handle of your joint chain.
  9. Make sure that the Ik Blend slider is still at 0.000 and select Key > IK/FK Keys > Set IK/FK Key.
  10. Drag the current time indicator forward in time 1 frame.
  11. Drag the Ik Blend slider to 1.000 and set a key.

    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.

  12. Drag the current time indicator along the Time Slider, translate the IK handle, and set keys as desired.

To insert IK within FK animation (whether or not the FK is controlled by Set IK/FK Key)

  1. Go to the first frame of the time range where you want to insert IK.
  2. Select the IK handle and set a key (Key > IK/FK Keys > Set IK/FK Key).
  3. Go the end frame of the time range where you want to insert IK, select the IK handle, and set a key (Key > IK/FK Keys > Set IK/FK Key).

    This creates a blend region, where any keys you set between these two bounding keys will not inadvertently change the animation outside of their range.

  4. Turn on the IK Solver (Key > IK/FK Keys > Enable IK Solver).
  5. Manipulate the IK handle and use Set IK/FK Key as desired for the frames between the bounding keys.

To insert FK within IK animation controlled by Set IK/FK Key

  1. At the first frame of the time range where you want to insert FK, select the IK handle and set a key (Key > IK/FK Keys > Set IK/FK Key).
  2. At the last frame of the time range where you want to insert FK, select the IK handle and set a key (Key > IK/FK Keys > Set IK/FK Key).
  3. Turn off the IK Solver (disable Key > IK/FK Keys > Enable IK Solver).
  4. Rotate the desired joints and use Set IK/FK Key as necessary for the frames between the bounding keys.

To insert FK within IK animation not controlled by Set IK/FK Key

  1. At the first frame of the animation, select the IK handle, turn on Solver Enable, and set a key for Solver Enable.
  2. At the end frame of the time range where you want to insert FK, select the IK handle and set a key (Key > IK/FK Keys > Set IK/FK Key).
  3. At the first frame of the time range where you want to insert FK, select the IK handle and set a key (Key > IK/FK Keys > Set IK/FK Key).
  4. Turn off the IK solver (disable Key > IK/FK Keys > Enable IK Solver).
  5. Rotate the desired joints and use Set IK/FK Key as necessary for the frames between the bounding keys.
Note: After FK animation, a joint chain may flip to an undesired position when you enable the IK solver. See Troubleshoot unexpected joint flipping with the IK solver.

Related topics

Parent topic: IK/FK blending