8

602 Chapter 12: Animation
A mixdown can correct two types of problems
during transitions between foot-based motions:
• A foot sliding as it transitions from one planted
motion to another.
• A leg extending completely straight
(hy per-extending) unnaturally to reach a
planted position.
The mixdown options on the Mixer
Preferences dia log (page 2–628)
can help correct
these problems. To access this dialog, click
Preferences on the Motion Mixer toolbar.
To have an effect on a mixdown, these options
must b e set before the mixdown is computed. If
Prompt for options at each Mixdow n is tur ned
on, you will be prompted to set these options
each time you compute a mixdown. Otherwise,
the mixdown uses the settings on the Mixer
Preferences dialog.
The options in the Mixdown Options group
determine if and how the mixdown affects
transitions between clips w ith planted feet.
Enforce IK Constraints affects planted feet, while
Filter Hyper-Extended Legs affects unnaturally
straig ht legs. Turn on Prompt for options at
each Mixdown if you want to be asked for these
settings each time you do a mixdown. For
more information on these options, see
Mixer
Preferences Dialog (page 2–628)
.
Tip: You should not rely on the mixdown process
to correct extreme problems with clips or
transitions. For the best results, adjust t ransit ions
before a mixdow n to minimize sliding feet
and hyper-extending legs. See
Working with
Transitions (page 2–592)
.
Procedures
To perform a mixdown and copy it to the biped:
1.
SelectthebipedintheMotionMixerby
clicking the biped name at the upper left of the
trackgroup set.
2. FromtheMotionMixermenu,chooseBipeds
>ComputeMixdown.
If Prompt for options at each Mixdown is
turned on in the Mixer Preferences dialog , you
will be prompted for mixdown options. Click
OK to start the mixdown.
A progress bar at the bottom of the Mixer shows
the progress of the mixdown process. After a
fewmoments,anewtrackcalledMixdownis
created as the last track in the biped’s mix.
You can turn the track on and off by clicking
the track. When the track is solid, the Mixdown
track is on (active), and the biped performs
the animation in the mixdown. When the
track appears with hatchmarks, the tr ack is
off (inactive), and the biped performs the
animation in the raw mix.
3. Click the Mixdown track to make it active.
4. Scrub the time slider or play the animation to
check the transitions. If they need correction,
turn off the Mixdown track, correct the
transitions, and compute the M ixdown again.
Repeat until the transitions are correct.
5. With the Mixdown track ac tive, choose Bipeds
menu > Copy Mixdown to Biped.
6. Tur n off Mixer Mode if it is on.