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to accept the new bone and location.
Figure 9.4
shows this second bone.
Hit the E key again, and drag the tail
of this even newer bone up to the
base of the neck. Do it twice more,
pulling those bones to the top of the
neck and the top of the head.
Figure
9.5
shows the entire spine chain.
Yours probably won't look exactly
like that, but in rigging, positioning
is crucial. The joints between the
bones will be the actual pivot points
for your character. Having them at
the wrong place will produce unre-
alistic deformations, and you will
find yourself fighting with your rig
just to get things to look right. So,
using RMB selection and the G key,
try to get your rig in side view to
look just like the one in
Figure 9.5
,
paying special attention to both ver-
tical and horizontal positioning rela-
tive to the neck and head, and the front and back of the rib cage.
Figure 9.4
A second bone.
Figure 9.5
The entire spine chain.
Notice that when you select a single joint with the RMB and move it, both of the attached bones on
either side move to follow. This is because these joints are a single bone element that consists of the head
of one and the tail of another. Additionally, if you grab an entire bone that is a part of this chain and
move it, then both of the bones on either side of it will adjust their size and orientation to keep everything
connected. Each of these bones that you extruded from a previous bone's tail are called
connected chil-
dren
of the bone from which they “grew”—their parent bone. The parent-child relationships of bones
within an armature are the basic way that bones relate to and affect each other. In the same way that
moving your own arm at the shoulder makes the lower portion of your arm come along for the ride, so
too do parent-child bones work.
However, when dealing with bones, there are two kinds of parenting:
connected
and
disconnected
. The
bones you have just created for the spine, neck, and head are all connected—the tails and heads are com-
bined into a single unit. When you're animating, you'll find that connected children can rotate on their
own, but their head cannot translate away from the tail of their parent bone.
The other type of parenting is disconnected. The child bone comes along for the ride with any transfor-
mation that the parent has, but it is free to translate wherever it likes.
Figure 9.6
shows both kinds of
parenting, as well as two unrelated bones.
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