8

Working with Both Deformable and Rigid Envelopes 943
See also
Envelope Sub-Object (page 2–981)
Working with Both Deformable
and Rigid Envelopes
You can assign both Deformable and Rigid to a
given link. For example, you might assign both
to the shins, and size the envelopes differently to
gain the benefits of both.
First, size the deformable e nvelope to affect the
whole lower leg area and smoothly transition
into the thigh and ankle areas. Next, you define
a s maller rigid envelope to encompass the stiff
unbendable section of the shin. Increase the
weight of the rigid envelope to balance its effect
against that of the deformable envelope.
Some users might use both envelopes as a way to
have a bone affect two completely separate regions
of a mesh. The envelop es are sca led so that the
deformable envelope influences certain vertices on
onesideofthelinkandtherigidenvelopeaffects
the other side.
See also
Envelope Sub-Object (page 2–981)
Adjusting Link Par ameters
Physique creates a continuous spline through
eachofthejointsinthehierarchy. Thesplineis
represented by an orange line within the object.
It maintains continuity through each joint: as a
joint angle changes, the spline passing through the
joint remains a smooth curve. Physique relies on
the deformation spline to obtain smooth bends of
the skin object. Physique offers bias and tension
controls to adjust the shape of the deformation
spline.
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 2–986)
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 par a meters (page
2–987)
:
• Bend parameters affect the curvature of the
deformationsplinethroughthejointatagiven
link. As a result the skin deformation can range
from more angular at the joint to more like a
stiff rubber tube.
• Twist parameters control how the sk i n 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 the
twist is distributed along the link and across
the joint.
Twist parameters apply to link rotat ion whose
axis is the same as the axis a long 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