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728 Chapter 13: reactor
Note:
The icon’s position has no effect on the
constraint’s behavior.
To a ttach obj ects to the spr ing:
1.
Create the Spring and the object(s) to connect
using it.
2. If you do not want to assign a second body to
the spring, turn off the Parent check box on the
spring’s Prop erties rollout if necessary.
3. Click the Child pick button and then select the
object to use as the child object in one of the
viewports. This attaches the Spring to the bo dy
at the body’s pivot point.
4. Ifthespringistwobodied,repeatstep2,using
the Parent pick button to set the parent object
for the spring.
To create the spr ing and attach t he objects in a single
step:
•SeetheScripts (page 2–817) topic.
To change the atta chment positions for the bodies:
1.
With the Spring constraint selected, open the
Modify panel.
2. In the modifier stack, open the Spring’s
sub-object list.
3. Highlight the option corresponding to the
object whose attachment point you want to
move: Parent Space or Child Space. If t he
Spring is single-bodied, Parent Space allows
you to move the world attachment position.
4. The appropriate space becomes active in the
viewport and can be move d using the Move
tool. The attachment point maintains its
position relative to its corresponding object; for
example, if you move the child object, its space,
and hence its attachment point, moves with it.
The attachment point doesn’t actually have to
be on the object.
If you move the attachment points s o that
they’re inside or beyond the Spring rest length,
you will see the attachment points represented
bylargeboxmarkersandtherestlength
denoted by small box markers. The difference
between the two is displayed in red.
5. To reset the attachment point to the object’s
pivot, reattach the o bjec t to the Spring.
Alternatively, if you click the Align Spa ces To
Each Body button, both attachment points will
be reset to their respective body’s pivot.
To ali gn the par ent and child constrai nt spa ces:
1.
Ensure that the constraint is selected in one of
the view ports.
2. In the Align Spaces To group, click the button
for your chosen alignment. You can find out
more about the alignment options in the
Working With Constraint Spaces (page 2–726)
section.
Interfa ce
Modifier Stack
Child Space—At this sub-object level, you can
select and move the constraint space for the child
object, including the point relative to the child
where the Spring is attached to it. When you
assign a child b ody to the Spring, the Child Space
attachment point is set to the child’s pivot point.
If you alter the posit ion of the attachment point,
it maintains its new position relative to the child
during the simulation.