Link Controller (Animated Hierarchies)

The Link controller lets you animate the transfer of hierarchical links from one object to another. For example, you could have the same object passed from object to object.

Note: For the most predictable results, parent objects should be animated before the links are added to the controlled object. If the parent’s animation needs to be adjusted, the link should be deleted first, and then reassigned after the parent’s animation has been modified.

You access and assign the Link controller in the Motion branch.

Reference

Motion Panel/Link Parameters rollout:

Contains all the controls specific to the Link controller

Add Link: Select and then click the object that you want to act as hierarchical parent. The name of the selected object appears in the list window. The frame at which you add the link is the frame where the control is passed. You can adjust this with the Start Time spinner, described below. You can add the same object more than once as a link.

Delete Link: Select an object name from the list window, then click the Delete Link button.

List Window: Displays the objects used as links. Select them for use in conjunction with the Delete Link button and the Start Time spinner.

Start Time: Displays and lets you adjust the frame time at which the highlighted link object first takes control. Select one of the object names in the list window to enable this spinner and see the frame at which this object becomes parent. You can now adjust the value to change when the link transfer takes place.

PRS Parameters (rollout): Contains the same controls found in the standard PRS Transform controller.

Key Info (rollout): Provides the same controls as a standard Transform controller.

How To

To combine a Link controller and a Path controller:

You can’t directly use a Link controller to switch an object that’s already been assigned a Path controller. Instead, you use a dummy. Follow these steps to animate a sphere moving along a helix, and then transfer the sphere to a swinging arm.

1. Create a scene consisting of a helix (tapered, with a few turns), a small sphere, a dummy, and a cylinder for the swinging arm.
2. Assign a Path controller to the dummy, and assign the helix as the path.
3. The dummy moves along the helix.
4. Center the sphere on the dummy.
5. Select the sphere, go to the Motion panel, and open the Assign Controller rollout.
6. Assign a Link controller as the sphere’s Transform controller.
7. Go to frame 0, click Add Link, then click the dummy.
8. The name of the dummy appears in the list window. When you drag the time slider, the sphere moves up the helix along with the dummy.
9. Adjust the cylinder so that it points in from the side toward the helix. Rotate the cylinder back, and then animate it so that, at some mid-frame (40-60), the cylinder swings around and its tip coincides with the position of the ball traveling about midway up the helix. You’ll also need to reposition the cylinder’s height.
10. Go to the end of the animation, and rotate/animate the cylinder to continue the swing.
11. The sphere should be moving up the helix, and a cylindrical arm swinging in from the side, passing its tip near the sphere at the point where the sphere is about midway up the helix, and then the cylinder continuing its swing as the sphere continues up the helix.
12. Go to the frame where the tip of the cylinder comes closest to the sphere (The point where you want the transfer to take place.)
13. Select the sphere, click Add Link in the Motion panel, and then click the cylinder.

When you play the animation, the sphere moves up the helix, and then transfers to the tip of the cylinder, which swings it around.

Note: For the most predictable results, parent objects should be animated before the links are added to the controlled object. If the parent’s animation needs to be adjusted, the link should be deleted first, and then reassigned after the parent’s animation has been modified.