8

Edit Object Dialog 675
simulation. Objects included for collision in this
dialog can collide with the cu rrent object.
Note: For every potential collision, you should
explicitly specify both colliding objects. For
example, if you s pecify that Box01 is to collide
w ith Box02, you should also specify that Box02
is to collide with Box01. This is primarily for
keeping track of your simulation; if you specify the
collision for only one object, it works for the other
as well. While it is not necessary to specify that
Box02 collides with Box01, this is the only way to
update the Assign Object Collision list for Box02.
The Assign Object Effects dialog func tions
similarly to the
Edit Object List dialog (page
2–677)
.
Collision Tes t group
Specifies the type of boundary used for collision
testing.
Box—A bounding box is used to test collision.
This is the fastest method. If your object is a box
or close to a box shape, this option is both fast and
accurate.
Cylinder—A cylindrical form is used to test
collision. The "height" axis of the cylinder is
aligned with the local Z axis of the object.
Sphere—A spherical form is used to test collision.
Mesh—Uses the sur face of the object to c alculate
the collision. This option is the most accurate, but
also takes far longer to calculate than the previous
three metho ds. Use this only when your object is
too complex to work properly with the first three
options.
Recalculate Properties group
Specifies when to recalculate the properties of
an object that changes over the course of the
animation. Specifically, the properties refer to the
mass moment of the object. The mass moment of
anobjectcanbedefinedasthemeasureofhow
the mass in an object is distr ibuted with respect
to the center of mass of that object. Altering the
mass moment changes the way an object responds
to torque. If y our object is changing shape over
time, and you want to t ake this into account for the
simulation, you should recalculate the properties.
Never —No ca lculation is per formed beyond the
first calculation for the dynamics solution.
Ever y Fra me—Theobject’spropertiesare
recalculated for every frame.
Ever y Cal c I nterva l—Theobject’spropertiesare
recalculated at each "Calc Inter val." You set the
Calc Inter v al (interval of calculation) in the
Time Parameters rollout; it specifies how many
calculations are performed for each frame of the
simulation time range.
Material Editor Physical Properties group
Three of an object’s physical properties are taken
by default from its material: bounce, static friction,
and sliding frict ion; see
Dynamics Proper ties
Rollout (page 2–1320)
. Use these settings in
this group to accept or override the material’s
dynamics properties.
Bounce—Specifies how far the object bounces
after collision. Available only if Override Material
Bounce is on.
Override Material B ounce—Enables the Bounce
spinner when you want to use a specific value
that’s different than that assigned by the object’s
material. When using a multi/sub-object material,
you c an assign different Bounce va lues to the
sub-materials, and thus to different faces of an
object. But if you use an override value, it affects
the whole object only.
Copy to Obj ect’ s Ma terial —Copies the value in the
Bounce spinner to the material assigned to the
object.