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932 Glossary

Dynamics

Biped Dy namics (page 3–916) calculate a biped’s

airborne trajector y, the b ending of its knee or

knees on landing, and the biped position so it

maintains balance when the spine is rotated. When

parameters change, dynamics cause the biped to

adapt.

Dynamics Blend

A parameter in the Body sec tion of the Key Info

rollout (page 2–954),usedwithfr eeform animation

(page 3–945). Blends between biped and spline

dynamics. Select the Body Vertical track (the

vertical track of the biped’s center of mass), and

use Dynamics Blend to control the amount of

gravity in an airborne period, such as in a running

or jumping gait. Dynamics Blend has no effect on

awalkingmotionwherefootstepsoverlap.

Ease Cur ve

Ease curves vary the t iming of a function curve.

An unaltered function curve charts the value of

an animated parameter over time. An ease cur ve

charts changes to the timing of the function curve.

Changing ease curve values shifts the time of the

original t r ack left or rig ht.

The horizontal scale of an ease curve represents

normaltime,justasitdoesforallfunctioncurves.

The vertical scale of an ease curve represents the

time scale of the func tion curve the ease curve is

applied to. Changing the shape of an ease curve

changes the way time is interpreted by the affected

function curve.

Thevalueoftheeasecurveataparticularframeis

a f rame value from the original track. For example,

iftheeasecurveis0atframe0and10atframe10,

the origi nal track plays at its original speed. If the

ease curve value at frame 10 increases to 20, the

original track plays to frame 20 by fr ame 10: it has

been sped up by a factor of two.

An Ease Cur ve Ex ample

Imagine you have animated a bird flying around

the sky. After viewing the animation you decide

that you want to change the position of the bird so

itmovesquicklyatthebeginningoftheanimation

and then slows to a leisurely pace toward the end.

You could accomplish this change by editing

position keys, ranges, and function curves but

it would require more work than using an Ease

curve. Applying an Ease curve to the Position

trackprovidesaquickandeasysolution.

Dragging the Ease curve causes time to compress

near the beginning of the animat ion and stretch

out near the end. You can tell that the bird’s

motion starts out fast and then slows down by

look ing at the effect the Ease curve has on the

P osition function curves.