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Animation

Here we shall discuss only rigid motions. The motion could be applied to a visible object or to the camera (or both, though that is not preferable in the interest of clarity). Usually it better to to create an object hierarchy to orchestrate the animation better. For example, if an arrow is to turn around its base point, then it is a good idea to place a null object at the base, and make it the parent of the arrow (or of its components, if it is made of multile parts like the shaft and the tip). To create the effect of looking at the object while walking around it, you should add a null object at the centre, and make the camera its child.

So we shall pretend that you have a hierarchy A > B > C > ..., and you are moving A. Open the time line. The time position should be at 0.0. Now we shall alternate two steps that we shall call snap and move.

Snap: Select all the objects in the hierarchy, and hit ctrl-shift-A to select all the tracks and then hit ctrl-k to create a key frame in each with the current configurations.

Move: Move the time indicator to the next position (say 1.0), and select only the top of the hierarchy $A.$ Move it as you please using the orbit tool. If needed you may also move objects down the hierarchy.

Keep on appying the two steps alternately, until you get all the keyframes necessary.

By default the keyframes are interpolated with splines. This naturally produces a pleasing ease-in and ease-out effect. However, for academic animations this may not be desirable. So we need to use (piecewise) linear interpolation instead. This is achieved by selecting each track individually and choosing "Edit track" from the right click menu. (The item will be disabled if multiple tracks are selected.) Now choose "Linear" from the drop down menu.