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738 Chapter 14: Character Studio
GravAccel values increase height of ju m p.
(Left=500, M iddle=1000,Right=1500).
You can change GravAccel at any time during the
animation process to affect the biped’s vertical
airborne motion, both for keys already created and
for animation not yet created. This value cannot
be animated; t he current GravAccel value is used
throughout the biped’s footstep sequence.
Changes to the GravAccel parameter have no
effect whatsoever on the amount of time the biped
spends in the air.
Tip: If you want to change GravAccel back to its
default value but don’t remember what that was,
you can find out by creating another biped of the
same height and noting its GravAccel value.
Note: If there is not enough gravitational
acceleration or time in the air to account for
differences in vertical height (such as a biped
fallingfromfootstepsonaledgeinslowmotion),
the biped is placed on the ground at the touchdown
frame, causing a discont inuity. You can fix this
by either increasing GravAccel or increasing the
amount of time between footsteps in Track View.
See
Editing Footstep Timing (page 2–727) .
Touch a nd Lif t Dy na mics
When footsteps are activated for a footstep pattern
that includes airborne periods, Body Vertical keys
are set at each Touch and Lif t keyframe.
Basedonthetimeintheairandthebiped’sheight,
character studio calculates the heig ht to which the
biped will jump. From this, the software figures
outhowhardthebiped’slegswouldhavetopushat
the Lift frame to reach this height, and how much
the legs would have to bend to absorb the force of
the landing at the Touch fr ame. Body Vertical keys
are set at the Lift and Touch frames accordingly.
You can adjust the timing of touch and lift
dynamics by:
• Changing Body Vertical keys at the Touch and
Lift frames.
• Setting, changing or deleting Body Vertical
keys during a footstep.
• Changing the stiffness or springiness of the
biped’slegsatTouchandLiftframeswiththe
Ballistic Tension parameter.
B allistic Tension
Ballistic tension refe rs to the stiffness or
springiness of the biped’s landing at the end of
a jump, or takeoff at the start of a jump. The
Ballistic Tension p arameter (page 2–809) changes
the biped’s motion only when it is set for footsteps
immediately preceding or following an airb orne
period.
You can edit the Ballistic Tension parameter only at
Body Vertical keyframes where the body touches
down (a Touch key) or lifts off (a Lift key). On the
Motion panel
Tr ack Selection rollout (page 2–800) ,
Body Vertical must be selected and a key must
be present at the current frame. With footsteps,
a Body Ver tical key is always set automatically at
the landing footstep’s Touch f rame and the takeoff
footstep ’s Lift frame.