Figure 5-2. The EaseBoth interpolator
A spline Interpolator can be used to create a number of different animations, by specifying different
parameters. In general a spline is a type of curve that is described by four points, a start point, an end
point, and two control points. For the sake of interpolation, the start and end points are considered
fixed, and what is specified when creating a spline interpolator are the control points.
Many drawing applications have a tool that allows the user to create a line and then adjust the curve
by moving the control points.
Figure 5-3 shows a spline curve that can be modified.