Graphics Programs Reference
In-Depth Information
Before discussing the technical parts, let's first ask ourselves—what is the purpose of
performing all these adjustments to the armature? The answer can be summarized as—
sharpening the axe before cuing a tree. The armature is already the structure that will
drive the mesh when animaing, so it is important that we can really have control over
it. The purpose is twofold—avoiding undesired behaviors (for example, a knee bending
backwards), and giving the animator a lot of control over the armature (and thus, the
mesh) without having to perform complex tricks. As the desired scenario is having a very
flexible rig and making life easy for animators, we must resort to some technical methods
for solving diferent kinds or problems, and the soluion ofered by Blender allows us to
create special relaionships (parening and constraints) between diferent bones. Playing
with these "building blocks", we can construct very complex rigs that have a lot of animaion
funcionality emerging directly from the setup, thus fulilling the purpose of aiding the
animator. It's true that in this project we are using a very simple setup, but the whole idea is
the same, no mater how complex the setup is.
Parenting
For one part, we have parening. Parening is the most common relaionship that we can
establish between two or more objects in a 3D package, not only when talking about
animaion, but also for other purposes.
The idea behind parening is geing the child object to "follow" the transformaions of its
parent. If the parent moves, the child element moves along with it, if the parent is scaled,
the child item will also be scaled accordingly. This creates the idea of dependency, which
is the whole goal. Parening is what allows us to create a strong dependency upon another
object's state. Noice, though, that this dependency is quite simplisic: All transformaions of
a parent (move, scale, and rotate) affect its children.
Constraints
For the more complex aspects, we have constraints. Constraints are a mechanism to create
different kinds of dependencies between objects, some of them simple (for example
Copy
Location
) and some of them complex (for example
Inverse Kinematics
). The useful thing
about constraints is that they ofer many parameters, which come with their own disinct set
of problems. These problems can be resolved by using them with the correct tweaks to their
parameters. A good example is the
Copy Location
constraint: It can be used to transfer the
enire locaion from the target object to the constrained one, or it can only be applied to one
of the coordinates.
The
Inverse Kinematics
constraint that we are using in our setup is one that allows us to
easily control the feet of our character, thus helping a lot to get the normal behavior of feet:
Once they hit the ground, they stay quiet, no mater how much other parts of the body
move. The
Inverse Kinematics
constraint achieves this by adjusing muliple properies of
the bones of the chain automaically for us.
