9

Hinge Constraint 747
A. Twist Axis
B. Plane Axis
C. Twist X Plane Axis
Back to Rag Doll Constraint (page 2–737).
Hinge Constra int
Create panel > Helpers > reac tor > Hinge
Menu bar > reactor > Create Object > Hinge Constraint
reactor toolba r > Create Hinge Constraint button
The Hinge constraint allows you to simulate a
hinge-like action between two bodies. reactor
lets you specif y an ax is in local space for each
body, with a position and a direction. During the
simulation, the two axes attempt to match po sit ion
and direct ion, thereby creating an axis around
which the two bodies can rotate. Alternatively, you
canhingeasinglebodytoanaxisinworldspace.
You can also limit the rotation between the
attachedobjectsrelativetothehingeaxis,allowing
you, for instance, to create a door that can
open only to a specified extent. You define this
limitation with respect to an axis perpendicular to
the hinge axis for each body.
A Hinge constraint is simulated only if it has the
correct number of rig id bodies attached and is
included in a valid Constraint Solver (page 2–736).
When not selected, an invalid Hinge is red in the
view por t.
Procedures
To create a Hinge constraint:
• Chooseoneoftheaboveoptions,andthenclick
in any viewport to add the Hinge constraint.
Note: The icon’s position has no effect on the
constraint’s behavior.
To a ttach objects to the H inge:
1.
Create the Hinge and the objects to connect
using it.
2. On the Hinge’s Properties rollout, click the
Childpickbutton,andthenselecttheobjectto
use as the child object in one of the viewports.
By default, this attaches the constraint so that
itsaxisgoesthroughthechildbodypivotpoint
and the axes are aligned with the child bo dy’s
local space. The constraint axis is aligned with
the child’s Z axis, and the perpendicular axis
used for rotation limits is aligned to the child’s
Xaxis.
3. If you do not want to assign a second b o dy
totheHinge,turnofftheParentcheckboxif
necessar y.
4. If the Hinge is to be two-bodied, repeat step 2,
usingtheParentpickbuttontosetParentfor
the Hinge.