The smoothanim.Movie shows how the smooth animation curves button may be applied to automatically define apparently complex motion with just a few event markers (key frames).
Open the smoothanim.mdl to see how the button settings were made for this animation.
To set up the animation, Sphere 1 was positioned at each of the four corners to create
the first set of event markers. The smooth animation curve button defaults to curve in/out.
To make the next set of event markers, simply Option-drag the existing markers to the
new place in the timeline, and set the animation curve button as desired. Repeat for the
final set of event markers.
The Offset smooth-animation-curves button for Sphere 1 event markers are set as follows:
for time 1.05 to 4.00 the button is set to curve in/out at each of the markers.
for time 5.05 to 7.05 the button is set to straight in/out at each of the markers.
for time 9.00 to 11.00 the button is set to straight in/curve out at each of the markers.