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736 Chapter 14: Character Studio
backward to compensate when the character
bends over.
• When Balance Factor is 2 and you rotate the
spine forward, the head retains its or iginal
vertical alignment while the COM sw ings
backward. The hips compensate strongly f or
the shift in body weight. This setting can be
useful for violent or acrobatic motions.
In order to affect the animation, the balance factor
must be set before you animate t he biped. The
balance fac tor can be animated to give the biped
different reactions to bending motions over the
course of the animation.
The Balance Factor parameter appears in the Key
Info rollout > Body section.
Procedure
To set the bal ance f actor:
1.
On the Motion panel
,turnoffFootstep
Mode if it is turned on.
Note: The Key Info rollout is accessible only
when Footstep Mode is turned off.
2. Expand the B ody bar on the Key Info rollout.
3. Go to the frame where you want to set the
Balance Factor.
4. Click Body Horizo
ntal to select this
track
(page 3–1117)
.
5. If no Body Horizon
tal key exists at the
frame where you want to set the Balance Factor,
createonebyclickingSetKeyintheKeyInfo
rollout.
6. Change the Ba lan
ce Factor parameter.
There is no need t
o click Set Key again after
setting the Balance Factor parameter.
7. Rotate the biped’s spine.
The biped’s hips and/or head shift position
based on the Balance Factor value.
Adjusting Vertical Motion
A
ballistic gait
is any footstep pattern in which
there are periods w ith no feet on the ground,
causing the biped to become airborne, or
ballistic
.
Running and jumping are ballistic gaits, while
walking is not.
WhenBipedDynamicsisturnedoninthe
Dynamics & Adaptat ion rollout (page 2–833)
and
you activate footsteps, the B ody Vertical keys that
are automatically generated during a ballistic gait
period will take grav ity and landing speed into
account. The parameters described in this sect ion
affect B o dy Vertical keys created in this m anner.
Air bor ne D yna mics
With footsteps, each air borne period always
begins and ends with Body Horizontal and Body
Vertical keys. These keys define the position of the
biped at lift-off and touchdown.
When the biped is airborne and Biped Dynamics
is turned o n, the vertical motion is governed by
physically based dynamics. Its airborne trajectory
is based on the current gr avity sett ing, the height
of the Bo dy Vertical key at lift-off and touchdown,
and the amount of time in the air.
By default, there is no Body Vertical key at the peak
of the biped’s trajectory; the biped’s peak airborne
height is calculated and enforced automatically.
You cannot, for example, set a Bo dy Vertical key
at the peak of an airborne trajectory and move
the biped up or down. If you attempt to do so,
the biped will snap back to its original airborne
height. Although this will cause a
Body Vertical
key (page 2–725)
to appear on the Track Bar and
in Track View, the key will have no effect on the
biped’s airborne height.