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758 Chapter 14: Character Studio
3.
Move the biped’s other hand so it is in contact
w ith the prop, and set a key for the hand.
4. Select the prop and set a key for it.
5. Movethetimeslideraheadoneframeandset
anotherkeyfortheprop.
6. On the Key Info rollout, expand the Prop
section.
The lists for Position and Rotation coordinate
spaces should be available. Change the Position
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 that 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 colla pse the tra nsfor ms of a pr op:
1.
Animate the prop however you like. You can
add list controllers to the prop as you can to any
other part of the biped.
2. When the animation is correct, select the prop.
3. In the Motion panel hierarchy l ist, select 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, make the
appropriate choices, and then click Collapse.
After a shor t delay, the track bar displays the
keys that have b een added.
Tip: If you see a different Properties dialog that
doesn’t offer y ou the Collapse button, y ou are
too low in the hierarchy. Select the next level up
in the hierarchy and try again.
Freef orm a nd IK
Using IK Keyframe Parameters
Bipedsinversekinematicssolutionhasthree
parameters set at each key of the arm and leg
keyframe tracks. As t he limb moves through each
key:
IK Blend sets the motion interpolation to be a
blend of forward and inverse 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 position of the hand
to move the ar m 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 t he IK path. 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 have 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 w ith 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 turned off.
Setting a free key creates a key with IK Blend
setto0,andBodyturnedon.JoinToPrevIK
Key is turned off.