9

Bones System 405
a con tinuous skin mesh. You can animate bones
with forward or inverse kinematics. For inverse
kinematics, bones can use any of the available IK
solvers (page 2–440),orthroughInteractive (page
2–480) or applied IK (page 2–481).
Dinosaur character modeled using bones
Bones are renderable objects. They hav e several
parameters, such as taper and fins, that can be
usedtodefinetheshapethebonerepresents.The
finsmakeiteasiertoseehowtheboneisrotating.
For animation, it is very important that you
understand the str ucture of a bone object. The
bone’s geometry is distinct from its link. Each link
hasapivotpointatitsbase.Thebonecanrotate
about this pivot point. When you move a child
bone, you are really rotating its parent bone.
Itmightbeusefultothinkofbonesasjoints,
becauseitistheirpivotplacementsthatmatter,
more than the actual b one geometry. Think of the
geometry as a visual aid that is drawn lengthwise
from the pivot point to the bone’s child object.
The child object is usua lly another b one.
Bones s ystem seen alone and inside a wireframe model
Any hierarchy can display itself as a bone structure
(see Using Objects as Bones (page 1–410)), by
simplyturningonBoneOnintheBone Editing
Tools rollout (page 1–411).
See also
Bone Tools (page 1–411)
Cr e at i n g Bo n e s
You star t creating bones by clicking the Create
Bones button on the Bone Editing Tools rollout
(page 1–411),orbyclickingtheBonesbuttonin
the Systems category on the Create panel.
To create bones, do the following.
1. Your fi rs t click in a viewport defines the start
jointofthefirstbone.
2. The second click in a vie wport defines the start
joint of the next bone. Visually only one bone
is drawn at this point because bones are visual
aids drawn b etween two pivot points. It is the
actualpivotpoint’splacementthatisimportant.
3. Each subsequent click defines a new bone as
a child of the previous bone. The result of
multiple clicks is a single chain of bones.
4. Right-click to exit bone creation.
This creates a small “nub” b one at the end of
the hierarchy, which is used when assigning an