8

Path Constraint 383
the Pat h Parameters rollout with the constraint
settings, double-click Path Constraint in the list.
Add Path—Adds a new spline path that influences
the constrained object.
Delete pa th—Removes a p ath f rom the target list.
Once removing the path target, it will no longer
influence the constrained object
Weig h t—Assigns and animates weight values for
each target.
%AlongPath—Sets the percent that the object is
positioned along the path. This duplicates the
Value spinner in the track Properties dialog for the
Percent track in Track View. If you want to set keys
toplaceanobjectatacertainpercentalongthe
path,turnonAutoKey,movetotheframewhere
you want the key set, and adjust the % Along Path
spinner to move the object.
Note: The % Along Path value is based on the
parameterization of the spline path’s U value. A
NURBS curve might not have an evenly spaced
Uvalue,soavalueof50%AlongPathmightnot
translate visually to 50 per cent of the NURBS
cur ve’s length.
Follow—Aligns the object to the trajectory as it
follows the contour.
Bank—Allows the object to bank (roll) as it
negotiates the curves of the spline.
B ank Amount—Adjusts the amount of the banking
to one side or the other, depending on whether the
value is positive or negative.
Smoothness—Controls how rapidly the roll angle
changesastheobjectmovesthroughbendsinthe
trajectory. Smaller values will make the object
more responsive to subtle changes in the curve,
whilelargervaluessmoothoutjerking.Thedefault
value is a good value for general damping along
the curve. Values below 2 tend to make the action
jerky, but values a round 3 can be very usef u l for
simulating a certain deg ree of realistic instability.
Allow Upside Down—Turn on to avoid the situation
in which an object flips when going around a
vertically oriented path.
Constant Velocity—Provides a constant velocity
along the path. When off, the velocity of the object
along the path varies depending on the distance
between the vertices on the path.
Loop—By default, when the constrained object
reaches the end of a path it c a n no longer move
past the end point. The loop option changes this
behavior so that when the constrained object
reaches the end of the path it loops back to the
starting point.
Relative—Turn on to maintain the original
position of the constrained object. The object will
followthepathwithanoffsetdistancebasedonits
original world space position.
Axis—Defineswhichaxisoftheobjectisalignedto
the trajectory of the path.
Flip—Turn on to flip the direction of the axis.
The following controls are located on the
Hierarchy panel while the IK button is active:
Active—Activatesanaxis(X/Y/Z).Allowsthe
selected object to animate along the activated path.
Limited—Limits the r ange of motion allowed on
an active path. Use in conjunction with the From
and To spinners.
Ease—Causes a joint to resist motion as it
approaches its From and To limits. Simulates an