8

1320 Chapter 16: Material Editor, Materials, and Maps
depending on the current shader (page 2–1310) .
The last four rows are always Bump, Reflection,
Refraction, and Displacement, in that order.
Note: The sub-material and sub-map buttons for
most materials and maps have check b oxes beside
each button. These turn that branch of the material
or map off or on. For example, in the Top/Bottom
material, the Top Material and Bottom Material
buttons each h ave check boxes. Similarly, the
Checker map has two map buttons, one for each
color. Each button has check box beside it that lets
you turn off that color’s map.
Ambient and Diffuse Map Lock
In the Maps r ollout, the lock button to the right
of the Diffuse Color map button locks ambient
mapping to diffuse mapping. It is on by default.
Usually it makes sense to use the same map for
the ambient and diffuse components. To use
different maps for ambient and diffuse, turn off the
lock button. The map button for Ambient Color
becomes available.
D yna mics Pr oper ti es R oll out
Material Editor > Standard material > Dynamics Properties
rollout
The Dynamics Properties rollout lets you specify
surfacepropertiesthataffecttheanimationofan
object upon collision with another object. If there
are no collisions in your simulation, these settings
have no effect. The dynamics properties are used
by the
Dynamics ut i lit y (page 2–663) .
Since the Dynamics P roperties rollout is available
at the top level of any material (including
submaterials), you can specify differen t surface
dynamic properties for each face in an object.
There are also controls in the Dynamics utility that
letyouadjustthesurfacepropertiesattheobject
level, but only the Materials Editor lets you alter the
surface properties at the sub-object level, through
use of a
Multi/Sub-Object material (page 2–1403) .
As a default, the values in the Dynamics Properties
rollout provide a surface that’s similar to
Teflon-coatedhardenedsteel.
Interfa ce
B ounce Coeffi cient—Sets how far an object bounces
after hitting a surface. The higher the value, the
greater the bounce. A value of 1 represents a
"perfectly elastic collision," or a bounce in which
no kinetic energy is lost. D efault=1.0.
If you’ve seen the desktop toy with four ball
bearings swinging back and forth on strings and
hitting one another, you’ve seen an example t hat
comes very close to a b ounce coefficient of 1.
Generally, hardened steel or a super ball have a
bounce near 1, while lead has a bounce near 0.
Static Friction—Sets how difficult it is for the object
to start moving along a surface. The higher this
value, the more difficult. Default=0.0.
If something weigh s ten pounds and sits on Teflon
(a st atic fric tion of near 0), it takes almost no force
to make it move sideways. On the other hand, if it
sits on sandpaper, then the static frict ion might
be very hig h, on t he order of 0.5 to 0.8. A static
friction near 1 is ver y difficult to create in the real
world without adhesives or friction material.
Sliding Friction—Sets how difficult it is for the
object to keep movi ng over a surface. The higher
this value, the more difficult for the object to keep
moving. Default=0.0.
Once two objects begin to slide over one another,
static frict ion disappears and sliding friction t a kes