8
1024 Chapter 14: Character Studio
parameters, while suitable for birds, fish, insects,
and snakes, are not rich enough to animate the
microstructure of bipeda l motion. Therefore,
several features in Crowd are focused on the
special needs of bipeds.
In order to generate the required level of nuance,
animated motion clips form the basis for the
repertoire of biped movements. In other words,
during a Biped/Crowd simulation, the delegates
have no effect over the motion of the Biped, they
only set goals to be achieved using clips available
in the Motion Flow graph. With this approach,
known as
motion synthesis
,theanimatorcan
precisely control details in the motion either
byusinghandanimationoremployingmotion
capture to produce a set of clips that describe how
a member in the crowd behaves.
For example, if you wanted to animate a crowd
of marathon runners making their way through
the streets of a cit y, you would need motion clips
for various kinds of walking, running, jogging,
resting, drinking water, cheering, etc. In effect,
eachofthemotionsyoumightexpecttoseeina
marathon race could be represented as a clip. But
motion must be more than a fragmented collec tion
of clips. You must also consider how motions
might be sequenced. Which motion transitions
arepossiblefromagivenmotionclip?
To best u nderstand this process, study this topic,
read the procedure
Using bipeds in a crowd
simulation (page 2–1027)
, and then do the related
tutorials in the
character studio Tutorials
,in
the lessons Working with Crowd Animation >
Advanced Crowd/Bipeds and Crowd of Sw imm ing
Bipeds.
M oti on Flow Networ k a nd Poss i ble
Scripts
Biped’s
Motion Flow (page 2–894)
functionality
provides the mechanism for defining how separate
motions fit together into a fluid animation. In
effect, the motion flow network describes w h ich
motions can follow from other motions. Once the
motion flow network is defined, a broad set of
animatedactionsispossiblebyfollowingdifferent
paths through the network. In Biped, a path
through the network is called a motion flow scr ipt.
For example, shown below is a motion
flow network used in the sample file
walkers.max
.Youcanfindthisfileinthe
cstudio\tutorials\biped_crowds
folder in your
3dsMaxpath.ThisfolderalsocontainstheBIP
files used in the motion flow network. You can
access these files only if you have installed tutorials
on your hard disk. For information on installing
tutorials, see the
Installation Guide
.
This is a fairly simple network of possible motions,
because the characters can only start, stop, turn
at 90 degree angles left and right (
walk_L90
and
walk _R90
), and do an about-face (
walk_180
).
However , for more natural crowd interaction, it’s
advisable to expand the motion flow network
toincludeshorter,morefinelytunedvariations
such as turning at 45 degree increments, moving
in different directions whi le facing the same way,
loitering motions, and moving at different speeds.
The Biped Motion Library has a comprehensive
list of clips for you to experiment with.
Tip: You can create motion clips that curve
slightlytotheleftandrightbyapplyingBiped’s
footstep-b ending operation to straight-line