Graphics Programs Reference
In-Depth Information
Now, if you feel you're having a hard
time wrapping your mind around this prob-
lem, don't feel bad; you're not alone. Even
the best IK solving engines have a difficult
time with this.
When the rotation axis that is recorded
second
(pitch) nears/exceeds +/- 90°, IK
can start to have problems. As the pitch
angle nears/exceeds +/- 90°, the item can
instantly “spin” around to face the opposite
direction. Often, this will happen suddenly,
over the course of a single frame. This is
called
flipping
.
At the bottom of the Bone | Properties win-
dow, LightWave has a set of Muscle Flexing
and Joint Compensation settings for each
bone. These help LightWave preserve the
volume of the character's joints as bones
bend and the object's mesh (or “skin”)
flexes.
Figure 16-24
Here, you see the difference between the
character's hand when Muscle Flexing and
Joint Compensation are active for the bones
of the fingers, and when they are not.
The important thing to know about Mus-
cle Flexing and Joint Compensation is that
these functions
only work with the bones'
pitch axis
!
Note
There are as many ways of setting up a
character rig as there are people to do the
setups. Everyone will find his own sets of
rules that work for him.
Over the course of your career, you will
hear many opinions as far as the “best” way
of doing things. In my experience, there is
no “best way.” There are only ways that
work more easily for the ways in which your
mind solves problems. Try what sounds
interesting, keep it if it works for you, and
always
keep your mind open to finding new
and better ways of working!
Joint Compensation and Muscle
Flexing
Note
This section on joint compensation and mus-
cle flexing gets into some pretty heavy-duty
LightWave and mathematical concepts. If
you're just starting out, or if you have little
desire to get into the “hard-core” aspects of
character rigging, please feel free to skip
this section, moving on to the next section,
called “Flipping.”
Figure 16-25
