9

Surface Constraint 397
example, the controlled object will position itself
as if the missing portion were still there.
Since the Surface constraint only works on
parametric surfaces, if you apply a modifier that
converts the object to a mesh, the constraint will
no longer work. For example, you can’t use it with
a cylinder with a bend modifier applied.
Procedure
Example: To animate a sphere over the surface of
a cylinder:
1.
IntheTopviewport,createacylinderanda
sphere.
2. Select the sphere, open the Motion panel,
expand the Assign Controller rollout, and then
expand the Transform heading in the list.
3. In the list window, click the Position item
and then click Assign Controller.
4. In the Assig n Position Controller dialog,
choose Surface and then click OK.
The Surface Controller Parameters rollout
replaces the Key Info rollout.
5. Click Pick Surface, and then select the cylinder.
6. TurnonAutoKey,andplacethetimesliderat
frame 0.
7. UsetheVPositionspinnertomovethesphere
to a starting position at the bottom of the
cylinder.
8. Place the time slider at frame 100.
9. Use the V Position spinner to place the sphere
at the top of the cylinder.
10. Set U Position to 300.
Turn off Auto Key and play the animation. The
sphere moves over the surface of the cylinder
inahelicalpath.
Interfa ce
The Surface Constraint Parameters rollout is on
the Motion panel.
Current Surface Object group
This group provides a metho d for selecting and
then displaying the selected surface object.
Text—Displaysthenameoftheselectedobject.
Pick Sur fa ce—Selects the object you want used as a
surface.
Sur face Options group
This group provides con trols for adjusting the
position and orientation of the object along the
surface.
U Position—Adjusts the posit ion of t he controlled
object along the U coordinates of the surface
object.
V Position—Adjusts the position of the controlled
object along the V coordinates of the surface
object.
No Alignment—When on, the controlled object is
not reoriented, regardless of its position on the
surface object.