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1092 Chapter 14: character studio
Links depicted by deformable spline.
Yo u c a n u s e c o n t r o l s a t t h e Link sub-object level
(page 2–1135) to adjust the skin behavior about a
given link. These link parameters define how the
skin deformation behaves, relative to the motion
of the underlying skeleton.
There are four kinds of link parameters (page
2–1136):
• Bend parameters affect the curvature of the
deformationsplinethroughthejointatagiven
link.Asaresulttheskindeformationcanrange
from more angular at the joint to more like a
stiff rubber tube.
• Twist parameters control how the skin deforms
when a joint rotates along its length, as in
turning a doorknob. Consider, for example,
winding up the rubber band on a toy airplane
propeller; Twist parameters determine how t he
twistisdistributedalongthelinkandacross
the joint.
Twist parameters apply to lin k rotation whose
axis is the same as the axis along the length of
the link.
• Sliding parameters control how the skin moves
along the length of a link as a joint rotates. On
theoutside,thesidewheretheangleisgreater
than 180 degrees, the skin moves toward the
joint. On the inside, the side where the joint
angle is less than 180 degrees, the skin moves
away from the joint.
The sliding effect tightens the outside to keep
detail at the joint and prevent the facets of the
mesh from moving apart. It relaxes the inside to
prevent the mesh from bunching up at the joint.
• Radial Scale parameters affect the influence on
the skin caused by scaling links of the skeleton.
Cert ain settings, such as Breathe and Stretch,
react to scaling of the skeleton, but only with
standard 3ds Max b ones or a 3ds Max hierarchy.
Note: Bipeds and 3ds Max IK con trollers don’t
support scaling.
Link Scale provides a way to g lobally scale
all the vertices influenced by the link. CS
Amplitude scales the effect of bulge cross
sections across the entire link. It can be used
for animated scaling of the bones or for general
mesh adjustments. The intent is not to edit the
character itself, but rather the effect the bones
have on it.
You set Link parameters at the sub-object level, in
the Physique Link Settings rollout (page 2–1136).
Par tial Blending and Weight
Assignments
Most often, you will want to use envelopes to
correct the way skin behaves as the biped moves.
However, you can override envelopes by manually
assigning vertex properties. For example, you can
removetheinfluenceofinappropriatelinksfrom
selected vertices. You can also change the weight
distribution between link s for a single vertex by
using typ e-in weights.