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Surface Constraint 379
Surface Constraint
Animation menu > Constraints > Surface Constraint
Animation menu > Track View > New/Open Track View
> Select a position track in Track View Hierarchy. > Track
Viewtoolbar>AssignController>Surface
Surface constraints position the weather symbol s on the
globe.
The Surface constraint positions an object along
the surface of another object.
Thetypeofobjectthatcanbeusedasthesurface
object is limited to those whose surfaces can
be represented parametrically. Use the Surface
constraint w ith the follow ing types of objects:
•Sphere
•Cone
•Cylinder
•Torus
• Quad Patches (single quad patches)
•Loftobject
•NURBSobject
The su rface used is a "virtual" parametric surface,
and not the actual mesh surface. Objects with
a low number of segments mig ht have a mesh
surface quite different than the parametric surface.
The parametric surface ignores Slice and
Hemisphere options. So if the object is sliced, for
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
conver ts the objec t to a mesh, the constraint wi ll
no longer work. For example, yo u 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.
In the Top viewport, create a cylinder and a
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 Assign 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. Use the V Position spinner to move the sphere
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.
Tu rn off Auto Key and play the animation. The
sphere moves over the surface of the cylinder
inahelicalpath.