Apple Motion 3 - Manual (Page 459)

Chapter 5 Using Behaviors 459
Important: Several Simulation behavior parameters contain object wells into which
target objects used as attractors, repellers, orbiters, and so on, are dragged. Dragging
an object to a well may be tricky—be sure to click the object name in the Layers tab
and immediately drag the object to the object well (without releasing the mouse
button). The behavior must remain active even though you are dragging another
object in the Layers tab. If you click the object in the Layers tab and release the mouse
button, that object becomes selected, and the behavior’s parameters are no longer
displayed. This behavior is true of all wells, including mask source and image wells.
Align To Motion
The Align To Motion behavior changes the rotation of an object to match changes
made to its direction along an animation path. This behavior is meant to be combined
with Simulation behaviors that animate the position of an object or with a keyframed
animation path you create yourself.
Note: The Align to Motion behavior does not work on objects animated using the
Motion Path behavior. Instead, use the Snap Alignment to Motion behavior (in the Basic
Motion subcategory).
Unlike the Snap Alignment to Motion behavior, which produces absolute changes in
rotation that precisely match changes in direction, Align To Motion has a springy
reaction and creates a more lively effect.
In the above example, the fish travels along the keyframed animation path, but it isn’t
aligned to the animation path (notice the rotation handle). Using the Align To Motion
behavior, its angle of rotation moves so that it points in the direction of the animation
path. By adjusting the Drag parameter, you can make it careen wildly about its anchor
point as it goes around curves in the animation path.
HUD Control
The HUD has controls for the Rotation Axis, Axis, Invert Axis, Spring Tension, and Drag
parameters. When applied to a group or layer that contains multiple objects (such as
particles, text, or a replicator), the Affect Subobjects checkbox also appears in the HUD.
Before using Align To Motion After using Align To Motion