9

Special Features in reactor 713
Co operat ive Constraints
reactor includes a number of cooperative
constraints (page 2–735) that facilitate the
simulation of articulated bodies and machinery.
The Rag Doll constraint (page 2–737) allows the
simulation of constrained bodies with relative
rotation and twist angles limits similar to those
found in human and animal joints
The Hinge constraint (page 2–747) allows the
simulation of hinges (limited or not) and
hinge-like joints where movement is limited
around a specified axis, like elbows and knees
The Prismatic constraint (page 2–754) allows the
simulation of translation-only joints (limited or
not) like those found in robots and machinery
The Car-Wheel constraint (page 2–757) is
particu larly suited to the simulation of wheels
attached to a chassis. The wheels rotate (and can
be powered) about a given axis. Limited linear
motion relative to the chassis is allowed along a
user-defined suspension axis.
Using Point-Point constraint (page 2–750) with the
Limited option lets you limit the relat ive rotation
of the attached objects by a given degree around
each axis.
Using Point-Point (page 2–750) with the Stiff
Spr ing option constrains both objects as though
attached by a fixed-length bar (a very stiff spring).
Fr act u re Ob ject
The Fracture (page 2–770) object in reactor offers
excellen t usability and behavior. Objects inside
Fracture are standard Rigid Bodies and, as such,
you can add them to constraints, assigned initial
velocities, etc. You can tell pieces to break at a
specific time.
Constr a int M ani pula tion a nd Constr a int
Spaces
Constraints (page 2–724) in general restric t the
relative movement between two bodies (parent
and child) or between a body (child) and the
world, and use consistent, intuitive nomenclature
and setup metho ds. Springs, linear dashpots and
angular dashpots are referred as Simple Constraints
(page 2–727), while the other constraints (those
that are g rouped with a Constraints Solver (page
2–736)) are referred to as Cooperative Constraints
(page 2–735).