9

712 Chapter 13: reactor
9.8 m/s
2
.Otherwiseobjectsmightappeartofall
faster or slower than you expect.
Note: Due to CPU floating-point precision, a
physics engine is most acc urate when dealing with
numbers as close in magnitude to 1 as possible. In
other words, values like 10,000,000 work poorly, as
do values like 0.0000001. Therefore, for real-world
scenes, when creating objects of 1*1*1 s ize it is
most usef ul to be working in meters or feet, rather
than centimeters/inches or k ilometers/miles, in
that you most often simulate objects larger than
sugar cubes and smaller than football fields. It
is for this reason that t he default values in many
physics engines are usually specified in meters.
Sp ecia l Featur es i n rea ctor
A number of reactor features enhance speed and
usability. Thesoftwareletsyoucreatenewand
better animations that were virtually impossible
without reactor, and you can set up those
animations in an efficient, intuitive wa y. Here we
present s ome of the main features in reactor.
Two S imulation Engines
From the reactor utility interface, you can choose
to run your simulation with either of two engines:
Havok 1 or Havok 3.
If your reaction involves cloth, rope, or soft bodies,
you’ll need to stick with Havok 1, the version
included with previous releases of 3ds Max.
However, if you’re using rig id bodies only, you can
take advantage of the enhanced accuracy available
in Havok 3. For more information, see The reactor
Utility (page 2–805) and Havok 1 World/Havok 3
World Rollout (page 2–808).
Integr a ted User I nterf a ce
The reactor interface is f ully integrated in 3ds Max.
You can access funct ionality in reactor through
menus, quad menus and toolbars. All 2D and 3D
icons follow a consistent look and feel. The reactor
utility (page 2–805) parameters are arranged for
easy access.
Yo u c a n f i n d m o r e d e t a i l s i n :
• reactor (page 2–703)
• The reactor Utilit y (page 2–805)
Vertex Selection Inside reactor Modifiers
The reactor modifiers for deformable bodies
(page 2–777): C loth, Soft, and Rope, let you
select vertices and apply constraints (fix points,
keyframe points, attach to r igid b ody, attach to
deform ing mesh) to those vertices without leaving
the modifier or having to apply extra modifiers.
You can create and manipulate deformable
constraints (page 2–795) inside the modifier.