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620 Chapter 12: Animation
a node at each end of each clip. A transition track
has no nodes by default.
Weight Curv e Evaluation
By default, each track’s weight curve is set to a
valueof1.0acrosstheentiretrack,whichuses
100% of the t rack’s mot ion in the mix. When
you change the curve to dip to a value below 1.0,
the motion on the tr ack is mixed with the motion
on the tra ck below it. For example, if you set the
weight curve for two tracks in a trackgroup to 0.5,
thetwoclipswillbemixedequally.
Several tracks can be stacked in a trackgroup with
vary ing weight curves on each one. For each frame
in the animation, the Motion Mixer evaluates the
cur ve on the topmost track. If its weight curve is
lessthan1.0atthatframe,theMixerevaluatesthe
next tr ack down, and so forth. The Motion Mixer
adds up the weight curve values until the sum
reaches 1.0, and disregards tracks below that point.
For Transition tracks, one weight curve is used for
theentiretrack.OnLayertracks,weightcurves
are set individually for each clip.
Procedure
To adjust a weight curve:
1.
Open the Mixer, add a biped to the Mixer, and
create two tracks for a tra ckgroup. See Filtering
Mixer Tracks (page 2–612).
2. Place different motion clips on the tracks.
3. For the topm ost track in the trackg roup,
click Weight Mode to the right of the track
display.
The weight curve tur ns red to indicate it can
be edited.
Youhavetodothenexttwostepsonlyifthe
weight curve has no nodes, or would like to
create more nodes.
4. Movethecursoroverthelineuntilasmall
arrow appears. Click to set a node.
5. Move the cursor and click to set more nodes on
the weig ht curve.
Tip: On a transition track, you would ordinarily
set a node at each end of the track, and at
intervals in between. The number of nodes you
setdependsonthetypeofcurveyouwantto
make.Makeasfewnodesaspossibletogetthe
curve required for your animation.
6. Move the cursor over an existing node until a
cross cursor appears.
7. Click and drag to move the selected node
down ward.
The Motion Mixer mixes the motions from the
topmost track with the track below it on that
frame. The motions are mixed to a greater or
lesser degree depending on how low you set the
weight curve value for the topmost track.
Adding T ime War ps
Select a biped. > M otion panel > Biped Apps rollout >
Mixer > Motion Mi xer menu bar > Clips > Add Time Warp
GraphEditorsmenu>MotionMixer...>Clips>AddTime
Warp
You can cause varying changes in speed
throughout a clip w ith a time warp. Adding a time
warp to a clip allows you visually to squash and
stretch time over different parts of the clip. You
can use a t ime warp to:
• Causetheobjecttodosomepartsofthemotion
quickly and others slowly.
• Cause a particular motion within the clip to
occur at a specific time.
You use a time warp by picking a time within the
motion clip and dragging that time’s motion to
another time in the same clip. T he overall time of
the clip is u nchanged, so the object takes the same