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Edit Object Dialog 699
Density setting, the Mass value changes (when its
automatic value is not overridden).
Mass—Te c h n ically, m a ss i s t h e m e a sure o f h ow
many subatomic particles are in an object. In
3dsMax,it’scalculatedasaresultofdensity
times volume. Mass can is the resistance to
acceleration given a constant force. The greater
themass,themoreresistance. TheMassvalue,
when not overridden, is derived f rom the density
and volume, and the volume, w hen autom atica lly
calculated, is affected by the Calculate Properties
Using option.
Override Automatic Mass—Enables the Mass
spinner so you can specify the object’s mass.
When you override the automatic value, the Mass
value is no longer affected by the D ensit y or
Vo lu m e v a lue s .
Mass is affected by the Ca lculate Prop erties Using
options.
Volume—Thevolumeoftheobject,measuredin
cubic centimeters. When automatically calculated,
this va lue depends on the option chosen under
Calculate Properties Using.
Overr ide Automatic Volume—Enables the Volume
spinner so you can specif y the object’s volume.
When you override the automatic Volume value,
it’s no longer affected by the Calculate Properties
Using options, and it no longer affects the Mass
value.
Calculate Properties Using options
Specifies the type of geometry the simulation will
usetocalculatethemass,thevolume,andthe
mass moment. When the Mass and Volume values
are automatically calculated (their overrides are
turned off), changing these options affects the
volume, and thus the mass.
Vertices—Treats an object as a "poi nt cloud," or
a collection of vertices without segments. Each
vertex is given a mass of 1 gram, but the object
itself has no volume.
Surf ace—Treats the object as a hollow shell w hose
thicknessis1centimeter.Themassisderivedfrom
the surface area and the 1-centimeter thickness,
but the object has no volume.
Bounding Box—A bounding box surrounding the
exten ts of the object is used to calculate both the
volume(ofasolidboundingbox)andthemass
(based on the volume).
Bounding Cylinder—Similar to the Bounding Box
option, except that a bounding cylinder is used,
whose Z height axis is aligned with the local Z axis
of the object.
B ounding S phere—Similar to Bounding Box,
except that a bounding sphere is used.
Mesh Solid—The geometry of the object is used to
calculate both the volume and the mass, according.
Property Estimate Resolution options
Available only when the Mesh Solid option is
chosen. The Property Estimate Resolution settings
affect the accuracy with which the mass moment
is ca lculated. This determines how accurately the
rotation of the object responds to torque.
Gri d—A sample grid is used to calculate the mass
moment. The sma ller the cells in the grid , the
more accurate the calculation. The grid cells are
measured in centimeters, regardless of the current
display unit.
Overr ide Automatic Resolution—Lets the Dynamics
utility automatically set the grid size based on the
complexit y and size of the object. In addition, t he
lowest value that will b e automatically calculated
is plugged into the Grid spinner (which is also
unavailable). If you want to specify your own grid
valueusingtheGridspinner,butwantsomeidea
of where to start, turn off A utomatic Resolution
andthenturnitbackonagain.