2009

Simple Constraints
The simple constraints provided with reactor are:
Spring on page 3930
Linear Dashpot on page 3934
Angular Dashpot on page 3939
Unlike cooperative constraints, the simple constraint does not require you to
add it to a Constraint Solver on page 3945 helper. Instead, reactor adds all valid
simple constraints in a scene to the simulation by default. A two-bodied simple
constraint is valid if it has two rigid bodies attached, while a single-bodied
simple constraint is valid if it has one rigid body attached.
Spring
Create panel > Helpers > reactor > Spring
Animation menu > reactor > Create Object > Spring
reactor toolbar > Create Spring button
The Spring helper lets you create a spring-like effect between two rigid bodies
in the simulation, or between a rigid body and a point in space. During the
simulation, the spring exerts forces on the attached bodies in an attempt to
maintain its rest length. So, for instance, if the objects are pulled apart so that
the spring attachment points are further apart than the rest length, the spring
works to bring them back together again.
You can configure a spring's behavior by specifying its stiffness, damping, and
rest length. reactor also lets you choose whether the spring acts under
extension (when the attachment points are pulled further apart) or
compression (when the attachment points are pushed closer together) or both
(the default). A spring that acts only on extension behaves as if the objects
were joined with a rubber band.
You do not have to add a Spring constraint explicitly to a simulation, as all
valid springs in a scene are added to the simulation by default. A two-bodied
spring is valid if it has two rigid bodies attached, while a single-bodied spring
is valid if it has one rigid body attached. When not selected, invalid springs
will be colored red in the viewport.
3930 | Chapter 16 reactor