2009
NOTE If there is not enough gravitational acceleration or time in the air to account
for differences in vertical height (such as a biped falling from footsteps on a ledge
in slow motion), the biped is placed on the ground at the touchdown frame,
causing a discontinuity. You can fix this by either increasing GravAccel or increasing
the amount of time between footsteps in Track View. See
Editing Footstep Timing
on page 4200.
Touch and Lift Dynamics
When footsteps are activated for a footstep pattern that includes airborne
periods, Body Vertical keys are set at each Touch and Lift keyframe.
Based on the time in the air and the biped's height, character studio calculates
the height to which the biped will jump. From this, the software figures out
how hard the biped's legs would have to push at 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 frame. 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's legs at Touch and Lift
frames with the Ballistic Tension parameter.
Ballistic Tension
Ballistic tension refers 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
parameter
on page 4367 changes the biped's motion only when it is set for
footsteps immediately preceding or following an airborne 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
Track Selection rollout on page 4348, Body Vertical must be selected
and a key must be present at the current frame. With footsteps, a Body Vertical
key is always set automatically at the landing footstep's Touch frame and the
takeoff footstep's Lift frame.
Ballistic Tension can range from 0 to 1, with 0.5 as the default value. Increasing
Ballistic Tension to 1.0 makes the legs stiffer at takeoff or landing. Decreasing
the tension to 0.0 makes the legs springier and less stiff.
4222 | Chapter 17 character studio