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336 Chapter 12: Animation
Use Cas es
Followingisabrieflistofexamplesofspecificuses
for the Limit controller:
• Select the Y Rotation tracks of all finger bones
in a character’s hands and assign a Limit
controller. Use Set Key mode to pose the fingers
at the extremes of their ranges of motion and
then use the right-click menu (page 2–340) >
Set Upper/Lower Limit commands to limit the
fingers’ motion.
Note: Limits are included for Set Key via the
Other category.
• You apply a Noise controller to the X Rotation
track of a window shutter object to make it
rattle, but the object intersects the building
at the lower end of its motion range. Apply a
Limit controller to the track and set the Lower
Limitvaluetopreventtheintersection.
• Following from the previous example, sa y
the wind tears the window shutter f rom the
building at fr ame 100. If the Noise controller
isinaFloatListwithaBezierFloat,youcan
weight the noise to 0 at frame 100, when
the shutter is torn from the building by the
w ind, at which point the animator will key the
animation. Limits are unnecessary after f r ame
100. At frame 99, you’d u se Set Lower Limit.
Then, at frame 100, you’d edit the Lower Limit
value to set the limit to much lower, essentially
removing the limit. Finally, you would set
keyframestoanimateitsmovementpastframe
100.
Limi tati ons of the L imit Controll er
It’simportanttobeawareofthefollowing
limitations of Limit controllers:
• Limit controllers do not limit IK joints. All IK
solvers use their own limits, and ignore Limit
cont rollers. Interactive IK uses the current
controllers,butitalsohasitsownlimits,so
using Limit controllers with inter ac tive IK will
produce unpredictable results.
• The Limit controller currently supports only
Float controllers. Thus, the Limit controller is
currently available only under the name Float
Limit.
• Upper and lower limits values are expressed
inthesameunitsorcoordinatesasthoseused
by the limited controller. Thus, for example,
Float limits on an X Position track are in local
coordinates, not in global coordinates.
Procedure
Example: To use the Limit controller:
1.
Startwithananimatedobject,andopenCurve
Editor.
In this example, the teapot position was
animated on the X axis between extents of
about - 45 to 40, and on the Y axis between
extents of about -80 and 54.
2. Assign the Float Limit controller to a track. In
this example, we’ll assig n it to the X Position
track.
This opens the Float Limit Controller dialog,
where you can set limits and other va lues, but
you mig ht find it easier to do this interactively,
so for now just accept the defaults by closing
the dialog.
The track retains its original name (X Position,
in this example), but the icon has changed to