TYPE: Object State
TITLE: Dynamic Parent Operation

The Dynamic Parent operation allows you to do dynamically parent objects
over time. With it, you can easily pass child objects from one parent to
another (either within a single frame or over a range of frames). This
is done with the aid of a Blend object and several Null objects.

When you start this operation, you will be prompted to select the child
object which is to be passed between the parents. When you are done
selecting the child object, its wireframe will be drawn with a dotted
line for the duration of the operation.

Note: If the selected child object has no existing parents, then a Null
parent object (named 'start_null') will be created, and the child's
transformations will be transferred. This will modify any animation that
the child object may already have, so we recommend that the child object
only be animated after an start_null parent has been created for it.

Once the child object has been selected, the Operation controls toolbar
(above the Viewport) can be used to Add, Replace, or Snap transitions.

When you click the Add Transition button, the operation controls will
change to allow you to set the frame offset for the current transition.
You are also prompted to select the new parent to transition to.

If the frame offset is set to 0, then the transition will occur
instantaneously (i.e. at the current frame). If set to something larger
than 0, then the transition will occur over the specified number of
frames starting from the current frame. The transition is accomplished
by adding a special Null object named 'transition_null' to carry the
child object from the current frame to the destination frame (i.e.
current frame + frame offset) of the new parent.

Keys will be created in the Blend object's Sequence parameter, and in
the transition object's Transform parameters to accomplish the
transition.  These transition objects can then be animated to precisely
control the path of the child during the transition.

For transitions within a single frame (frame offset 0), special Null
objects named 'offset_null' are created to ensure there will be no popping
while  transitioning between parents. Also, special channel groups named
'Transition' are created to help manage the channels used.

The Replace Transition button will allow you to change an existing
transition (at the current frame) to the new parent. It modifies
existing keys at the starting and ending frames of the current
transition to do this.

The Snap Transitions button will go through all the keys of the Blend
object's Sequence parameter and snap the keys of the transition objects
to match the transitioning parents. This is often handy to fix the
transitions after the transitioning parents have had their animation
changed.

The Visibility button brings up a menu to control the display of the
transition objects associated with the currently attached child object.

See also: Blend
