Graphics Reference
In-Depth Information
as having movement that relates to those things. In general terms, the
movement of text on a screen usually conforms to simple activity. Movements
that relate to and demonstrate such qualities as weight or balance come
under the next category of animation: action.
Action
The
action
classification of animation relates to the identifiable movements of
an object or image that are natural to that object. The nature of the animation
that falls under this classification depends on a number of factors, principally
the nature of the object itself. The material the object is made of will influence
the action. The reason a tennis ball bounces more than a cannonball is due,
at least in part, to the material of which it is made, which allows for more
bounce; it is more flexible, being made of rubber rather than the metal of a
cannonball. We can all easily recognize the flexible movement of wooden
planks in a footbridge, though the flexibility is less evident in shorter and
thicker pieces of wood; we understand how cloth flutters when made into
a flag that hangs at the top of a flagpole and how it is less prone to flutter
when made into garments. We know that flesh is soft and metal is hard, that
concrete crumbles but does not do so as readily as biscuits.
Now consider the movement of the flame of a candle, smoke billowing up
from a garden fire, waves on water, leaves on a tree blowing in the breeze, and
thousands of other examples. All may be said to possess the kind of dynamic
range that can be attributed to those known objects and that the actions are
recognized by the viewer as belonging to those objects. There is even more
to take into consideration in animating subjects with an attributed action.
Objects not only demonstrate an action determined by their material or their
shape and size; their actions are also demonstrated by the external forces that
act on them. Gravity will impart an action; air resistance and wind power may
FIG 3.2
The movement of the candle
flame, the flaring match, and the water
droplets are classified as “action” within
the four A's of animation.
