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698 Chapter 12: Animation
the mass i n an object is d istributed with respect
to the center of mass of that object. Altering the
mass moment changes the way an object responds
to torque. If your object is changing shape over
time,andyouwanttotakethisintoaccountforthe
simulation, you should recalculate the properties.
Never—No ca lculation is per formed beyond the
first calculation for the dynamics solution.
Ever y Frame—Theobject’spropertiesare
recalculated for every frame.
Every Calc I nter va l—Theobject’spropertiesare
recalculated at each "Calc Interval." You set the
Calc Interval (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 Proper ties group
Three of an object’s physical properties are taken
by default from its material: bounce, static friction,
and sliding friction; see Dynamics Properties
Rollout (page 2–1479). Use these settings in
this group to accept or override the material’s
dynamics properties.
Bounce—Specifies how far the object b ounces
after collision. Available only if Override Material
Bounce is on.
Override M aterial 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.Whenusingamulti/sub-objectmaterial,
you can assign different Bounce values to the
sub-materials,andthustodifferentfacesofan
object. But if you use an overr ide va lue, it affects
the whole object only.
Co py to Objec t’s Material—Copies the value in the
Bounce spinner to the material assigned to the
object.
Static Friction—Specifies how hard it is to start
moving on a surface. Available only if Override
Ma terial Static Friction is on.
Override Material Static Friction—Enables the Static
Friction spinner when you want to use a specific
value that’s different than that assigned by the
object’smaterial.Whenusingamulti/sub-object
material, you can assign different Static Friction
values to the sub- materials, and thus to d ifferent
facesofanobject.Butifyouuseanoverridevalue,
it affects the whole object only.
Copy to Object’ s M ateri al—Copies the value in the
Static Friction spinner to the material assigned to
the object.
Sliding Friction—Sliding friction determines
how hard it’s for an object to keep moving over
a surface. Available only if Override Material
Bounce is on.
Override M aterial Sliding Friction—Enables the
Sliding Friction spinner when you want to
use a specific value t hat’s different than that
assigned by the object’s material. When using a
multi/sub-object material, you can assi gn different
Sliding Friction values to the sub-materials, and
thus to different faces of an object. But if you use
an overr ide value, it affects the whole object only.
Copy to Object’ s M ateri al—Copies the value in the
Sliding Friction spinner to the material assigned
to the object.
Physical Properties group
Provides controls that specify the physical
properties of the current object.
Density —Specifies the density of the object in
gramspercc.Asettingof1istheequivalentof
water, and useful for anything wooden, plastic, or
organic. The more dense an object, the slower it
will react to forces. There is a direct relationship
between density and mass, so when you alter the