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734 Chapter 13: reactor
Par ent S pa ce—
At this sub-object level, you can
select and rotate the offset rotation for the parent
bo dy. This is the rotation that the dashpot tries
to maintain for the parent body relative to the
child. When you assign the parent body to the
dashpot, this rotat ion is alig ned w ith the child
body’s local space. If you alter the rotation of this
sub-object, it m aintains its new rotation relative
to the parent. If the dashpot is single-bo d ied, this
rotation represents the world rotation to which the
dashpot t ries to align the Child Space axis.
Properties rollout
Par ent—When on, the dashpot has two bodies
and you can designate an object to be the parent
body. When off, the dashpot is s ingle-bodied and
the point o ccupied by the Parent Space sub-object
is the parent.
You assign the parent object by clicking this button
and then selecting a r igid body from any view port.
Thereafter the button displays the name of the
parent bo dy.
Child—Displays the name of the second rigid body
attached to the dashpot. You assign the child
object by clicking this button and then selecting a
rigid body from any viewport.
Align S paces To—Use these options to align the
bodies’ local constraint spaces. You can find out
more about each option in the Working With
Constraint Spaces (page 2–726) section.
Lock Rel a ti ve Tra n sf or m —When on, the relative
transform between the child and parent constraint
spaces is locked: If you move either space in the
viewport, the other space moves along with it.
Strength—Governs the size of the impulse the
dashpot will apply to each attached body, taking
into account the di fference in their relative offset
rotations(ChildSpaceandParentSpace).The
strength value is mass dependent – for example,
astrengthvalueof10willgenerateadifferent
behavior when connecting two 5 kg bodies than
whenconnectingtwo50kgbodies.Valuesgreater
than or equal to 0.0 are valid for this property.
Default=1.0.
Dampi ng—This value affects how quickly the
oscillation of the angular d ashpot settles down.
It governs the impulse applied to the connected
bodies due to their relative angular velocities.
Valid damping va lues are those greater than or
equal to 0. Default=0.1.
Tip: Typically,adampingvalueof1/10thofthe
stiffness yields good results.
Allow I nterpenetr ati on—When on, collisions are
disabled between the dashpot’s objects: During
the simulation, they can pass through each other.
Default=off
Disabled—When on, the d ashpot is not added to
the simulation.
Reset Default Values—Click this to set Strength,
Damping,andDisabledtotheirrespectivedefault
values.