Graphics Programs Reference
In-Depth Information
•
Pre Behavior
and
Post Behavior
tell
LightWave what to do
before
it reaches the
item's first keyframe and
after
it reaches its
last keyframe (respectively).
•
Constant
(as shown in the figure)
holds the value of the
first key
for
“infinity” before the first keyframe
begins and/or the value of the
last key
for “infinity” after the last keyframe.
•
Reset
sets the value of the graph
to 0 when it has no more keys with
which to work.
•
Repeat
plays the series of keys
over and over again,
ad infinitum
.
•
Oscillate
“ping-pongs” the anima-
tion set by the keys, reversing it when
it reaches the end and playing it for-
ward once again when it returns to the
beginning.
•
Offset Repeat
repeats the motion
but with everything shifted by the dif-
ference between the first and last keys
(this would make our curve here into
an infinite set of “stairs”).
•
Linear
continues the curve
infinitely, projecting it at an angle
established by the last two keys (or
first two keys, if we're talking about
Pre Behavior).
•
Incoming Curve
tells LightWave how
to handle the curve segment that is directly
to the
left
of the selected key.
•
TCB Spline
is LightWave's de-
fault setting, and it gives good results
most of the time, without having to
worry about tweaking the curves
much. (Tension, Continuity, and Bias all
affect the shape of the curve, based on
values from -1 to +1. Of these, I have
only ever found myself needing to use
Tension, and then only to put in a value
of +1 to get an item to ease into or out
of its keyed position.)
•
Hermite Spline
gives you little
“handles” that extend from the key,
allowing you to visually control the
shape of the curve. (It isn't quite as
controllable as a bezier spline.)
Alt-
dragging
on one of these handles will
let you split it from its partner, so it is
not a mirror of the handle on the other
side of the key.
Double-clicking
on a
handle that has been split will get it to
once again mirror the angle of the han-
dle on the other side of the key.
•
Bezier Spline
also gives you han-
dles, but you can move the position of
these handles a great distance relative
to their respective keys, giving you a
lot more control. (
Alt-dragging
and
double-clicking
on these handles splits
and reunites the handles with their
partners, just as with Hermite Spline
handles.)
•
Linear
gives you a straight line
inbetween from the previous keyframe.
•
Stepped
holds the value of the
previous key until the moment before
the stepped key, so it goes right from
one value to the next without any kind
of inbetweening (like what a traditional
animation “pencil test” looks like
before it goes to the assistant anima-
tors who put in the “missing” frames).
•
The
Footprints
drop-down (located
along the top row of pop-up menus) lets you
choose among several options: Leave Foot-
print, Backtrack Footprint, and Pickup
Footprint. Leave Footprint places a bit of a
“ghosted” image of how your curve looked
when you left the footprint. You can use this
as a visual reference to help you as you
tweak. If you totally mangle things, you can
use Backtrack Footprint to get back to the
