Attachment Controller

The Attachment controller is a Position controller that attaches an object's position to a face on another object (the target object doesn't have to be a mesh, but must be able to convert itself to a mesh).

By keying different attachments over time, you can animate the position of an object over the irregular surface of another object, even if that surface is changing over time.

Parameters for this controller are available in Motion Panel/Parameters, after the controller has been assigned.

Reference

Motion Panel/Parameters/Attachment Parameters rollout:

Attach To area

Object Name text: The name of the target object to which the source object is attached.

Pick Object: Select and pick the target object in the viewports to perform the attachment.

Align to Surface: Fixes the orientation of the attached object to the face where it’s assigned. When this is clear, the orientation of the attached object is not affected by the orientation of the face on the target object.

Update area

Key Info area

Current Key: Displays the current key number and lets you move to another key.

Time: Displays the current frame, and lets you move the current key to a different frame.

Position area

Face: The index of the face where the object is attached. (Spinner Value: int, 0 to 268435455 (FFFFFFF hex)

A: and B: The barycentric coordinates defining the position of the attached object on the face. (Spinner Value: float, -999,999 to 999,999)

Display window: Shows the position of the source object within the attachment face. You can drag within this window to adjust the position of the object relative to the face.

Set Position: Adjusts the placement of the source object on the target object. Drag over the target object to specify a face, and a position within the face. The source object moves accordingly over the target object.

TCB area

All of the items in this area are the same as in other TCB controllers. The orientation of the source object is also interpolated and affected by these settings.

Tension: (Spinner Value: float, 0 to 50)

Continuity: (Spinner Value: float, 0 to 50)

Bias: (Spinner Value: float, 0 to 50)

Ease To: (Spinner Value: float, 0 to 50)

Ease From: (Spinner Value: float, 0 to 50)

How To

To attach a cone to a bending cylinder:

Create the two objects, and animate the cylinder:

1. Create a cylinder in the Perspective viewport, with a Radius of 20, a Height of 10, and 10 Height Segments.
2. Create a cone in the Perspective viewport, with a Radius 1 of 15, a Radius 2 of 5, and a Height of 30.
3. Select the Cylinder, apply a Bend modifier, and set the Bend Angle to -70 degrees. Turn on Animate, move to frame 100, and set the Bend Angle to 70 degrees.

The cylinder bends from one direction to the other over 100 frames.

4. 4 Turn off the Animate button.

Now, assign the Attachment controller, and adjust the cone:

1. Select the cone.
2. In the Motion panel, open the Assign Controller rollout, click the Position track, click the Assign Controller button, and choose the Attachment controller.

The cone moves to the origin of the scene, and the Attachment Parameters rollout appears.

3. Click the Pick Object button, and then click the cylinder.

The name of the cylinder appears above the Pick Object button.

Go to frame 0, and Arc Rotate the Perspective viewport so you can see the top surface of the cylinder.

Note: The following step creates a key at whichever frame you’re on. If you perform it at a non-zero frame, a single key is created at that frame, and not at frame zero, so no animation results, unless you perform the step again at a different frame.

4. Click the Set Position button, and drag the mouse over the faces on the top surface of the cylinder.

The cone jumps to the top of the cylinder. As you drag the mouse, it jumps to whichever face you drag over.

5. Release the mouse when the cone is on the top surface of the cylinder.

Adjust the position of the cone, relative to the face:

1. Drag in the face display window to position the red x relative to the triangle representing the face. (Because of the radial arrangement of cap faces in a cylinder, the upper-left corner of the displayed triangle is the center of the cylinder cap. You can turn off Edges Only for the cylinder to see this, if you want.)
2. Try adjusting the A and B spinners to move the cone across the surface of the face.
3. Drag the time slider to various frames.

As the cylinder bends back and forth, the cone remains attached to its upper surface. You can continue adjusting the A and B spinners, as well as dragging in the face display window to adjust the cone’s position.

4. Remember the number in the Face spinner, and then lower the spinner value until the cone leaves the cylinder cap and begins jumping around various areas of the cylinder.

The Face spinner specifies which face the cone is attached to. As you change its values, the cone moves to different faces on the cylinder.

5. Reenter the original value in the Face spinner to return the cone to the top of the cylinder.
6. Play the animation.

The cylinder bends back and forth with a cone glued to its upper cap.