9.5.2

20. F-Curve Manager
F-Curves, short for function curves, control the interpolation between keys. Since they have no xed
units, they can be used to control any parameter that can be interpolated.
F-Curves are shown only for those animated parameters that can be
interpolated. Parameters that cannot be interpolated — such as the Shadow
setting of lights — do not have F-Curves.
The way in which keys are interpolated has a major effect on animation. In Figures 1 and 2, below,
two F-Curves are shown whose keys are in identical positions. If these curves were to control the
position of an object, the object would start in the same position for both curves and it would also
end in the same position. The difference between the two curves only affects what happens to the
object between the start and the end.
Figure 1: Linear Interpolation. Figure 2: Ease In interpolation applied to right-
hand key.
Suppose the two F-Curves above control a car that stops at trafc lights at frame 90. In Figure 1, the car
moves at constant speed (indicated by a straight line) and comes to a sudden halt at the lights. There is
no deceleration phase at all, thus the motion is unrealistic. In contrast, the curve in Figure 2 attens out
as frame 90 is approached. This causes the car to slow down gradually as it approaches the lights, just
as though a driver is applying the brakes. The resulting motion is realistic.
F-Curves give you an easy way to ease motion in and out, helping you to improve the realism of your
animation. In addition, F-Curves give you a graphical way to control animation, using smooth curves
to avoid abrupt, unnatural changes.
CINEMA 4D creates an F-Curve automatically for each animated parameter that can be interpolated.
To access the F-Curve for a particular track in the Timeline, click the ‘+’ symbol next to the track name
(Figure 3, below). This allows you to edit F-Curves directly in the Timeline.