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932 Chapter 14: Character Studio
Bones That Compress
Onewaytouseboneswiththebipedisto
use the Select and Link tool on the 3ds Max toolbar
to link the root of the bone to one part of the biped
andhavetheboneEndEffectorfollowanother
part of the biped. As the biped moves these bones
compress and expand.
In the im age of the mechanical leg, piston objects
are linked to the bones. As the bones compress
and expand, they also animate the linked piston
assembly. Asthebonescompressandexpand
in the abdominal area in the bottom im age, the
envelopes created by Physique for the bones
compress and expand to animate this area on the
mesh.
IK Solution
In the IK Controller Parameters rol lout, you
specify the accuracy of the IK solution and the
frame duration of the solution. For bones that
compress, you generally want an accurate solution
toensurethatthebonefollowstheendeffector
perfectly, without any dr ift. In the image of the
rollout Position has a value of 0, the least amount
ofallowabledistance(Rotationisatitsdefault
value of 1, the Rotation End Effector is not used in
this example). Iterations is set high, ensuring that
that the solution is accur ate, even if the character
is scaled down a great deal. Start and End Time
should span the animation.
Therearemanywaystouseboneswiththebiped.
You could automatically animate the bending of
a hose that is attached to a character’s shoulder
and mouth when the biped head rotates, for
example. Bones attached to the biped create links
and envelopes when Physique is applied; these
extra Physique links offer localized skin control if
necessar y.
Procedures
To mak e compressible bones (bones with end
ef fectors) :
1.
Create a bones system with end effectors.
2. Link the root of the bone to the appropriate
biped object.
3. On the Motion Panel specify an End Effector
Parent.
4. Specify another part of the biped.
5. On the Motion Panel set the Position Threshold
to 0.
6. On the Hierarchy panel > IK > Sliding Joints
rollout, turn on all the sliding parameters.
7. Animate the character.
The bones expand and compress with the
motion of the character.
To add a bone after Physique is applied using
Reinitialize:
1.
Tur n on Fig ure
mode.