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900 Chapter 14: character studio
from the right hand to the left hand, and click
Set Key again.
The prop will now follow the movement of the
left hand in the frames tha t follow.
Note: By default, the prop’s rotation remains in
Body space. Depending on your animation,
you might also want to set keys so the Rotation
space is Right Hand before the switch, and Left
Hand after the switch.
To collaps e the tr ans for ms of a pr op:
1.
Animate the prop however you like. You can
add list controllers to the prop as you can to an y
other p art of the biped.
2. When the animation is correct, select the prop.
3. In the Motion panel hierarchy list, selec t the
prop transform list you want to collapse, and
then right-click.
Aquadmenuappears.
4. Choose Properties from the quad menu.
5. In the dialog that is displayed, ma ke the
appropriate choices, and then click Collapse.
After a short delay, the track bar displays the
keys that have been added.
Tip: If you see a different Properties dialog that
doesn’t offer you the Collapse button, you are
too low in the hierarchy. Select the next level up
in the hierarchy and try again.
Freef or m a nd I K
Usi ng I K Key f r a me Par a meters
Biped’sinversekinematicssolutionhasthree
parameters set at each key of the arm and leg
keyframe tracks. As the limb moves through each
key:
• IK B lend sets the motion interpolation to be a
blend of forward and in v erse kinematics. This
allows you to blend swinging motions with
hand-or-foot directed motions. Rotating an
arm to move a hand is an example of forward
kinematics. Using the p osition of the hand
to move the arm is an example of inverse
kinematics. The default blend is 0.0, or full
forward kinematics. An IK Blend of 1.0 is full
inverse kinematics.
• Body or Object determines the reference
coordinate space of the IK p ath. This allows
you to move the IK path with your character’s
body or temporarily attach the hands or feet to
follow other objects. The default is Body.
• Join To Prev IK Key determines if the key
should be part of the previous key (and hav e the
same reference position as the previous key).
Biped has three automatic ways to set these
parameters. Setting planted, sliding, or free keys
creates keys with different combinations of these
three parameters.
• Setting a planted key creates a key with IK
Blend set to 1.0, Object and Join To Prev IK Key
turned on.
• Setting a sliding key creates a key with IK Blend
setto1.0,Objectturnedon,andJoinToPrev
IK Key tur ned off.
• Setting a free key creates a key w ith IK Blend
setto0,andBodyturnedon.JoinToPrevIK
Key is turned off.
IK B lend
The IK Blend control is in the Key Info rollout (page
2–954);visiblewhenyouexpandtheIKdivider
bar. You set IK Blend whi le in Keyf rame mo de .