9

780 Chapter 13: reactor
Mass—
The Cloth object’s mass in kilograms. This
affects the behavior during collisions with other
objects, and also the stretching caused by attached
rigid bodies (page 2–798): the higher the mass of
the cloth, the less st retching induced by the r i gid
body.
Fr iction Thecoefficientoffrictionforthecloths
surface. As with rigid bodies, this affects how
smoothly the cloth moves relative to surfaces it
contacts. The Friction values for both objects in
contact combine to produce a coefficient for the
interaction.
Rel DensityCloth has no volume, so reactor
cannot calculate its density. Instead, reactor
providesabuoyancypropertyforClothobjects,
which reflects its relative density. The default value
is 1.0, the density of water. This value is important
only if you are going to float or immerse the cloth
in water.
Air R esist ance—Theextenttowhichtheclothloses
energy as it moves.
Force ModelChoose the way forces in the
simulation affect your cloth object:
Simple Force Model—This default method is
suitable for most situations.
StiffnessThe stiffness of the cloth.
Dampi ng—How quickly the cloth dissipates
energy as it changes shape.
Complex Force M odel—This more-accurate
model of cloth dynamics is mor e
computationally expensive to simulate.
It provides parameters to specify the shear
and stretch stiffness separately, as well as a
physically accurate out-of-plane bend property.
Stretch—The cloth resistance to stretching.
BendThe cloth resistance to bending.
Shear—The cloth resistance to shearing.
Dampi ng—How quickly the cloth dissipates
energy as it changes shape.
Fold S tiffness Fold stiffness gov erns the cloth
resistance to folding.
None—By default, Cloth objects have no fold
stiffness, and behave l ike a lo ose material such
as silk.
Unifor m Model This model adds fold stiffness
uniformly across the surface of the cloth,
regardless of its topology.
Stiffness—The fold stiffness value.
Spatial M odel—This more-complex model of
fold stiffness can be useful if you are simulating
a complicated piece of cloth, such as a dress. It
allowsyou,forinstance,toaddfoldstiffness
only to sec tions of the cloth t hat are flat.
Stiffness—The fold stiffness value.
Distance—Thedegreeoffoldstiffnessper
unit area. A Distance value of 2 refers to
tw ice the average triangle edge length in the
cloth, so a large Distance value results in a
large concen tration of fold stiffness per unit
area.
Spread Angle—Controls the degree to which
fold stiffness is added to cloth when it has
a non-flat shape. The angle relates to the
threshold angle between two parts of the
cloth, below which st iffness is added. If this
valueis0.0,foldstiffnessisaddedonlyto
flat parts of the cloth.
Split AngleThedegreetowhichfold
stiffness is added; specifically, how fold
stiffnessisconcentratedalongthegridlines
of the cloths original mesh.
Av o id Se lf - Inters e c ti o ns—When on, the cloth will
not intersect with itself during the simulation. This
results in a more realistic-looking simulation, but
canincreasesimulationtime.