NoteIf you want to rotate
or key individual joints in a joint chain that already have IK animation,
turn on
Ik Fk Control. See
ikHandle.
To create an animation blend from FK
to IK
- Select the IK handle of the Ik chain
that you want to animate with FK.
- In the IK Solver Attributes,
drag the Ik Blend slider to 0.000.
The animation mode is
now set to pure FK.
- Select
Animate > 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).
- Deselect the IK handle.
- Select a joint in the IK chain, drag
the current time indicator along the Time Slider and 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 current joint and select the IK handle of your joint chain.
- Make sure that the Ik
Blend slider is still at 0.000 and select
Animate > IK/FK Keys > Set IK/FK Key.
- Drag the current time indicator forward
in time 1 frame.
- 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.
NoteWhen 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.
- Drag the current time indicator along
the Time Slider, translate the IK handle and set keys as desired.
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 beginning and
end of the FK animation, moving the current time 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 to FK).
Example
To insert IK within FK animation (whether
or not the FK is controlled by Set IK/FK Key)
- Open the Animation menu
set (press F2).
- At the first frame of the time range
where you want to insert IK, select the IK handle and set a key
by selecting
Animate > IK/FK Keys > Set IK/FK Key.
- At the end frame of the time range where
you want to insert IK, select the IK handle and set a key by selecting
Animate > IK/FK Keys > Set IK/FK Key.
We refer to the keys
you set in the prior two steps as bounding keys,
because they ensure that any keys you set between them will not
change the animation outside their range.
- Turn on
Animate > IK/FK Keys > Enable IK Solver.
- 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
- Open the Animation menu
set (press F2).
- At the first frame of the time range
where you want to insert FK, select the IK handle and set a key
by selecting
Animate > IK/FK Keys > Set IK/FK Key.
- At the last frame of the time range where
you want to insert FK, select the IK handle and set a key by selecting
Animate > IK/FK Keys > Set IK/FK Key.
We refer to the keys
you set in the prior two steps as bounding keys.
They ensure that any keys you set between them will not inadvertently
change the animation outside of their range.
- Turn off
Animate > IK/FK Keys > Enable IK Solver.
- 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
- Open the Animation menu
set (press F2).
- At the first frame of the animation,
select the IK handle, turn on Solver Enable,
and set a key for Solver Enable.
- At the end frame of the time range where
you want to insert FK, select the IK handle and set a key by selecting
Animate > IK/FK Keys > Set IK/FK Key.
- At the first frame of the time range
where you want to insert FK, select the IK handle and set a key
by selecting
Animate > IK/FK Keys > Set IK/FK Key.
We refer to the keys
you set in the prior two steps as bounding keys.
They ensure that any keys you set between them will not inadvertently
change the animation outside of their range.
- Turn off
Animate > IK/FK Keys > Enable IK Solver.
- Rotate the desired joints and use Set
IK/FK Key as necessary for the frames between the bounding
keys.
After FK animation, a
joint chain may flip to an undesired position when you turn on
Animate > IK/FK Keys > Enable IK Solver.
To undo the joint flipping and prevent it from occurring when you
turn on Enable IK Solver, do the following:
To eliminate unexpected joint flipping
after turning on the IK Solver
- Open the Animation menu
set (press F2).
- Undo the Enable IK Solver menu
item to return the joint chain to the position it had before flipping.
- Select the IK handle.
- Select
Skeleton > Set Preferred Angle.
- Select
Animate > IK/FK Keys > Enable IK Solver.
- Select
Animate > IK/FK Keys > Set IK/FK Key.
Continue using IK as
desired.