Graphics Reference
In-Depth Information
impart another kind of action, as will rain. The action of a bouncing ball on
a street will be very different from a bouncing ball on the moon or the same
ball at the bottom of the ocean. The one thing all of these “naturalistic” actions
have in common is that they are all subject to the same laws of physics.
The nature of movement is inextricably linked to the nature of the subject.
Boulders roll down a hill in the way they do because they are made of rock,
they are heavy, and more often than not they are uneven in shape. Leaves fall
to earth from a tree because they have been blown by the wind, but they do it
in a particular way due to their weight, shape, and size as well as the material
of which they are made. These characteristics give these objects a particular
and recognizable action. The key point here is that all of the subjects we have
covered move without the
intention
to move at all, let alone in any given way;
it is simply in their nature to move the way they do. The movement that we
witness demonstrates only those actions that are related to the object itself
and the forces acting on it. The intention to move is the topic that takes us
one step higher in the hierarchy of action.
Animation
The
animation
level of action classification describes all the movements,
naturalistic or not, that are generated from within an object or image
itself. Although these images or objects are still subject to external forces
acting on them, the motivating factor behind this movement comes from
within. A bouncing ball from our earlier example does not generate its own
movement; external forces do that. The external force made the ball move in
the first place; gravity causes it to fall, and the surface it hits and the material
properties of the ball determine the bounce. In contrast, cats and dogs and
mice all move as a result of their
intention
to move.
The complexity and range of dynamic possibilities of the various kinds
of movement are almost endless. If we simply look at the various types
of locomotion, we can see how they relate to the varying nature of the
structures that undertake locomotion; fish swim, birds fly, frogs hop, and
humans walk upright. The various types of physiognomy of the subjects—
some with legs (of varying numbers), some with fins, some that are smaller
than a pinhead, some larger than a London bus—determine the various
types of movements they make. Not all fish swim in the same manner,
and not all birds fly using the same flying technique. Some variations are
down to the choices the animal makes; other differences are a result of
physical and behavioral dissimilarities. These differences, along with the
various influences (physical and psychological) by which the creatures are
motivated, simply determine the type of action. Big or small, swimming
or flying, living creatures and their various movements have one thing in
common: They demonstrate a choice in their movement, and that is the
key to animation in this context:
intention
. A flag does not intend to wave, it
does so because of its nature and the forces that apply to it under any given
circumstance. However, a spider does intend to crawl across the floor, a lion
