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Deforming Meshes (Skin) 793
Advanced rollout
Internal Steps—Because deformable objects are
more complex to simulate, it is usually necessary
to perform more simulation steps (page 2–709) to
increase st ability. This parameter specifies how
man y steps will be taken internally to simulate
objectsinthiscollectionforeachsimulation
substep taken globally during the simulation. For
example, at 60 fps, simulating at one keyframe
(step) per frame, 10 substeps, at t hree internal
substeps for this collection, the objects in this
collect ion w i ll b e simulated using 60x10x3=1,800
steps every second , while the simulation in general
uses 60x10=600 steps per second. This allows the
objectsinthiscollectiontobesimulatedmore
accurately without slowing down the rest of the
simulation. In general terms, you c an think of it
this way:
• Precision (stability) of overall
simulation=Number of Substeps (as
specified in the Preview and Animation rollout
(page 2–806))
• Precision (stability) of objects in this
collection=Precision of overall simulation x
(multiplied by) Internal Substeps
Reset Default Values—Resets Internal Steps to its
default va lue.
Defor ming Meshes
A deforming mesh is a mesh whose vertices’
behavior has been key framed. The sk in of a
skinned character, where any deformation comes
from the underlying animated character rig, could
be used as a deforming mesh in reactor.
Why use deforming meshes? Firstly, rigid bodies
(page 2–716) and deformable bodies (page 2–777)
can collide with a deforming mesh as if it was
another reactor body. The deforming mesh
won’tbeaffectedbythecollision,buttherigid
body/deformable body will. So, for instance, you
can create deformable clothes for a deforming
mesh that you can drape realistically around his
body, or you can cause environmental objects to
react to the deforming mesh.
Yo u c a n a l s o a t t a c h d e f o r m a b l e b o d i e s t o
deforming meshes. This allows you, for example,
to attach physically-simulated hair, gar ments, or
tentacles to a ke yframed character. When the
character moves, its simulated elements swirl,
sw ing, or slither (as appropriate) a long with it.
This is known as secondary motion, and is an easy
waytoaddrealismtoyourcharacterswithout
having to animate t he behavior by hand.
Unlike the other reactor deformable body types,
you do not need to apply a special modifier to a