Autodesk 3ds Max 3ds Max - 2009 User Manual

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Space Warps and
Particle Systems

Space warps and particle systems are additional modeling tools. Space warps are “force fields”
that deform other objects, creating the effect of ripples, waves, blowing wind, and so on.
Particle systems generate particle sub-objects for the purpose of simulating snow, rain, dust,
and so on. (You use particle systems primarily in animations.)

See also:

■ Space Warp Objects on page 2685

■ Particle Flow on page 2795

■ Non-Event-Driven Particle Systems on page 3002

14

Space Warp Objects

Create panel > Space Warps

Space warps are nonrenderable objects that affect the appearance of other objects.
Space warps create force fields that deform other objects, creating the effect of
ripples, waves, blowing wind, and so on.

Space warps behave somewhat like modifiers, except that space warps influence
world space, rather than object space, as geometric modifiers do.

When you create a space warp object, viewports show a wireframe representation
of it. You can transform the space warp as you do other 3ds Max objects. The
position, rotation, and scale of the space warp affect its operation.

2685

Surfaces deformed by space warps

Left: Bomb

Right: Ripple

Rear: Wave

A space warp affects objects only when the objects are bound to it on page

2691. The warp binding appears at the top of the object's modifier stack. A space
warp is always applied after any transforms or modifiers.

When you bind multiple objects to a space warp, the space warp's parameters
affect all the objects equally. However, each object's distance from the space
warp or spatial orientation to the warp can change the warp's effect. Because
of this spatial effect, simply moving an object through warped space can
change the warp's effect.

You can also use multiple space warps on one or more objects. Multiple space
warps appear in an object's stack in the order you apply them.

NOTE You can take advantage of the AutoGrid feature to orient and position new
space warps with respect to existing objects. See AutoGrid on page 2597 for details.

2686 | Chapter 14 Space Warps and Particle Systems

Space Warps and Supported Objects

Some types of space warps are designed to work on deformable objects, such
as geometric primitives, meshes, patches, and splines. Other types of warps
work on particle systems such as Spray and Snow.

Five space warps (Gravity, PBomb, Wind, Motor, and Push) can work on
particle systems and also serve special purposes in a dynamics simulation. In
the latter case, you do not bind the warps to objects, but rather assign them
as effects in the simulation.

On the Create panel, each space warp has a rollout labeled Supports Objects
Of Type. This rollout lists the kind of objects you can bind to the warp.

Basics of Using Space Warps

Follow these general steps to use space warps:

1 Create the space warp.

2 Bind objects to the space warp.

Click Bind To Space Warp on the main toolbar (available from the
Select And Link flyout), and then drag between the space warp and the
object.

The space warp has no visible effect on your scene until you bind an

object, system, or selection set to it.

3 Adjust the space warp's parameters.

4 Transform the space warp with Move, Rotate, or Scale. The transforms

often directly affect the bound object.

You can animate space warp parameters and transforms. You can also animate
space warp effects by animating transforms of an object bound to the warp.

Particle Leakage and Deflector Space Warps

A deflector is a space warp that acts as a barrier to particles in particle systems.
Occasionally stray particles can leak through a deflector under the following
circumstances:

■ When a particle happens to hit the deflector too near the end or beginning

of a time interval, and numerical error in the solution doesn't report a hit

Space Warp Objects | 2687

■ When a particle hits too near the edge of a face referenced by a UDeflector,

and neither face finds it

■ When a particle is moving quickly and first appears too close to the

deflector, so the very first update cycle within the particle system takes it
past the deflector without the deflector ever seeing it

Often this isn't a problem because the particles bounce off solid objects, so
you don't see the errant particles. When it does cause problems, you can use
a planar deflector instead of a UDeflector, a collection of planars to
approximate the mesh, or a simple mesh to replace the planar. The solutions
vary, so where one has a glitch the other might work just fine.

If particles are moving fast and the deflector is in a particular position (for
example, it might be too close to the emitter) many particles can leak through
defectors. Sometimes you can fix this leakage by changing the particle system's
Subframe Sampling setting or the particle speed. Other times you must
reposition the deflector farther away from the emitter.

In addition, particles imbued with bubble motion on page 3067 can leak through
deflectors, particularly when set to high amplitudes. To avoid this, use
alternative methods of implementing bubble-like motion, such as varying
speed (see Particle Generation Rollout on page 3049), setting a higher angle for
the stream spread with spray systems (see Spray Particle System on page 3016,

Super Spray Particle System on page 3025), or using larger particles with an

animated texture map.

Space Warp Categories

There are four categories of space warps, available via the list on the Create
panel's Space Warps category.

Forces

These space warps are used to affect particle systems and dynamics systems.
All of them can be used with particles, and some can be used with dynamics.
The Supports Objects of Type rollout indications which systems each space
warp supports.

2688 | Chapter 14 Space Warps and Particle Systems

Motor Space Warp on page 2696

Push Space Warp on page 2691

Vortex Space Warp on page 2701

Drag Space Warp on page 2706

Path Follow Space Warp on page 2717

PBomb Space Warp on page 2712

Displace Space Warp on page 2727

Gravity Space Warp on page 2721

Wind Space Warp on page 2724

Deflectors

These space warps are used to deflect particles or to affect dynamics systems.
All of them can be used with particles and with dynamics. The Supports Objects
of Type rollout indicates which systems each space warp supports.

PDynaFlect Space Warp on page 2738

POmniFlect Space Warp on page 2732

SDynaFlect Space Warp on page 2745

SOmniFlect Space Warp on page 2743

UDynaFlect Space Warp on page 2748

UOmniFlect Space Warp on page 2746

SDeflector Space Warp on page 2751

Space Warp Objects | 2689

UDeflector Space Warp on page 2754

Deflector Space Warp on page 2757

Geometric/Deformable

These space warps are used to deform geometry.

FFD(Box) Space Warp on page 2760

FFD(Cyl) Space Warp on page 2767

Wave Space Warp on page 2777

Ripple Space Warp on page 2781

Displace Space Warp on page 2727

Conform Space Warp on page 2785

Bomb Space Warp on page 2789

Modifier-Based

These are space-warp versions of object modifiers (see Modify Panel on page

7633). Read more about these in Modifier-Based Space Warps on page 2793.

Bend Modifier on page 1208

Noise Modifier on page 1573

Skew Modifier on page 1668

Taper Modifier on page 1811

Twist Modifier on page 1837

Stretch Modifier on page 1752

Procedures

To create a space warp:

1 On the Create panel, click Space Warps.

The Space Warps panel is displayed.

2 Choose a category of space warp from the list.

3 On the Object Type rollout, click a space warp button.

2690 | Chapter 14 Space Warps and Particle Systems

TIP You can take advantage of the AutoGrid feature to orient and position
new space warps with respect to existing objects. For details, see AutoGrid
on page 2597.

4 Drag in a viewport to create the space warp.

See the topics for the various space warps for further details.

Bind to Space Warp

Main toolbar > Bind to Space Warp

Use the Bind to Space Warp button to attach the current selection to a space

warp on page 8132 or vice versa.

Procedures

To bind the current selection to a space warp:

1 Select an object

2 Click Bind to Space Warp.

Forces

3 Drag a line from the selected object to the space warp object. You can

also press H to select the space warp by name.

The space warp object flashes for a moment to show that the bind was
successful.

Push Space Warp

Create panel > Space Warps > Forces > Object Type rollout > Push

Create menu > Space Warps > Forces > Push

Bind to Space Warp | 2691

Push disperses a cloud of particles

The Push space warp applies a force to either particle systems on page 2795 or

dynamics systems on page 3852. The effect is slightly different, depending on

the system.

■ Particles: Applies a uniform, unidirectional force in a positive or negative

direction. A positive force moves in the direction of the pad on the
hydraulic jack. The breadth of the force is infinite, perpendicular to the
direction; you can limit it using the Range option.

■ Dynamics: Provides a point force (also called a point load) away from the

pad of the hydraulic jack icon. A negative force pulls in the opposite
direction. In dynamics, applying a force is the same as pushing something
with your finger.

2692 | Chapter 14 Space Warps and Particle Systems

Push viewport icon

Procedures

To create a Push space warp:

1 On the Create panel, click Space Warps. Choose Forces from the

list, and then on the Object Type rollout, click Push.

2 Drag in a viewport to define the size.

The Push warp appears as a hydraulic jack icon.

Forces | 2693

Interface

2694 | Chapter 14 Space Warps and Particle Systems

Timing group

On Time/Off Time The numbers of the frames in which the space warp begins
and ends its effect. Because Push moves the particles to which it's applied over
time, no keyframes are created.

Strength Control group

Basic Force The amount of force exerted by the space warp.

Newtons/Pounds This option specifies the units of force used by the Basic

Force spinner.

A pound is about 4.5 Newtons, and one newton is one
kilogram-per-second-squared. When Push is applied to particle systems, these
values have only subjective meaning because they depend on the built-in
weighting factors and time scaling used by the particle system. However, when
used in a dynamics system, the value listed is precisely the value used.

Feedback On When on, the force varies depending on the speed of the affected
particles relative to the specified Target Speed. When off, the force remains
constant, regardless of the speed of the affected particles.

Reversible When on, if the particle's speed exceeds the Target Speed setting,
the force is reversed. Available only if you turn on Feedback On.

Target Speed Specifies the maximum speed in units per frame before the
Feedback takes effect. Available only if you turn on Feedback On.

Gain Specifies how quickly the force adjusts to approaching the target speed.
If set to 100 percent, the correction is immediate. If set lower, a slower and
"looser" response occurs. Available only if you turn on Feedback On.

NOTE Setting Gain above 100 percent can result in over-correction, but is
sometimes necessary to overcome damping from other system settings, such as
IK damping.

Periodic Variation group

These settings introduce variations into the force by affecting the Basic Force
value randomly. You can set two waveforms to produce a noise effect.

Enable Turns on the variations.

Period 1 The time over which the noise variation makes a full cycle. For

example, a setting of 20 means one cycle per 20 frames.

Forces | 2695

Amplitude 1 The strength of the variation (in percent). This option uses the
same types of units as the Basic Force spinner.

Phase 1 Offsets the variation pattern.

Period 2 Provides an additional variation pattern (a second wave) to increase

the noise.

Amplitude 2 The strength of the variation of the second wave (in percent).
This option uses the same types of units as the Basic Force spinner.

Phase 2 Offsets the variation pattern of the second wave.

Particle Effect Range group

Lets you restrict the Push effect's range to a specific volume. This affects particle
systems only; it has no effect on dynamics.

Enable When on, limits the range of the effect to a sphere, displayed as a
tri-hooped sphere. The effect falls off increasingly as the particles near the
boundary of the sphere.

Range Specifies the radius of the range of the effect, in units.

Display Icon group

Icon Size Sets the size of the Push icon. This is for display purposes only, and
does not alter the Push effect.

Motor Space Warp

Create panel > Space Warps > Forces > Object Type rollout > Motor

Create menu > Space Warps > Forces > Motor

2696 | Chapter 14 Space Warps and Particle Systems

Motor disperses a cloud of particles

The Motor space warp works like Push on page 2691, but applies rotational
torque to the affected particles or objects rather than a directional force. Both
the position and orientation of the Motor icon affect particles, which swirl
around the Motor icon. When used in dynamics, the position of the icon
relative to the affected object has no effect, but the orientation of the icon
does.

Forces | 2697

Motor viewport icon (with particle system on the left)

Procedures

To create a motor space warp:

1 On the Create panel, click Space Warps > Forces > Motor. Choose

Forces from the list, then on the Object Type rollout, click Motor.

2 Click and drag in a viewport to define the size.

The Motor warp appears as a box-shaped icon with an arrow indicating
the direction of the torque.

2698 | Chapter 14 Space Warps and Particle Systems

Interface

Timing group

On Time/Off Time The numbers of the frames in which the space warp begins
and ends its effect. Because Motor moves the objects to which it's applied over
time, no keyframes are created.

Strength Control group

Basic Torque The amount of force exerted by the space warp.

N-m/Lb-ft/Lb-in Specify the unit of measure for the Basic Torque setting,

using common world measurements of torque. N-m stands for Newton meters,
Lb-ft stands for pound-force feet, and Lb-in stands for pound-force inches.

Feedback On When on, the force varies depending on the speed of the affected
objects relative to the specified Target Speed. When off, the force remains
constant, regardless of the speed of the affected objects.

Reversible When on, if the object's speed exceeds the Target Speed setting,
the force is reversed. Available only if you turn on Feedback On.

Target Revs Specifies the maximum revolutions before the feedback takes
effect. Speed is specified in units traveled per frame. Available only if you turn
on Feedback On.

Forces | 2699

RPH/RPM/RPS Specifies the units of measure for Target Revs in revolutions
per hour, minute, or second. Available only if you turn on Feedback On.

Gain Specifies how quickly the force adjusts to approaching the target speed.
If set to 100%, the correction is immediate. If set lower, a slower and "looser"
response occurs. Available only if you turn on Feedback On.

NOTE Setting Gain above 100% can result in over-correction, but is sometimes
necessary to overcome damping from other system settings, such as IK damping.

Periodic Variation group

These settings introduce variations into the force by affecting the Basic Torque
value randomly. You can set two waveforms to produce a noise effect.

Enable Turn on to enable the variations.

2700 | Chapter 14 Space Warps and Particle Systems

Period 1 The time over which the noise variation makes a full cycle. For
example, a setting of 20 means one cycle per 20 frames.

Amplitude 1 The strength of the variation (in percent). This option uses the
same types of units as the Basic Torque spinner.

Phase 1 Offsets the variation pattern.

Period 2 The next two spinners provide an additional variation pattern to

increase the noise.

Amplitude 2 The strength of the variation of the second wave in (percent).
This option uses the same types of units as the Basic Torque spinner.

Phase 2 Offsets the variation pattern of the second wave.

Particle Effect Range group

Lets you restrict the Motor effect's range to a specific spherical volume. This
affects particles systems only; it has no effect on dynamics.

Enable When on, limits the range of the effect to a sphere, displayed as a
tri-hooped sphere. The effect falls off increasingly as the particles near the
boundary of the sphere.

Range Specifies the radius of the range of the effect, in units.

Display Icon group

Icon Size Sets the size of the Motor icon. This is for display purposes only,
and does not alter the Motor effect.

Vortex Space Warp

Create panel > Space Warps > Forces > Object Type rollout > Vortex

Create menu > Space Warps > Forces > Vortex

The Vortex space warp applies a force to particle systems on page 2795, spinning
them through a whirling vortex, and then moving them down a long, thin
spout or vortex well. Vortex is useful for creating black holes, whirlpools,
tornadoes, and other funnel-like objects.

The space warp settings let you control the vortex shape, the well
characteristics, and rate and range of particle capture. The shape of the vortex
is also affected by particle system settings, such as speed.

Forces | 2701

Particle stream caught in a vortex

Procedures

To create a Vortex space warp:

1 On the Create panel, click Space Warps. Choose Forces from the

list, and then click Vortex.

2 Determine which world axis you want the vortex to spiral around, and

then drag in the appropriate viewport to create the space warp. For
example, if you want the vortex to spin around the vertical world axis,
create the space warp in the Top viewport. You can rotate the warp later
to change the vortex direction, and animate the warp orientation.

2702 | Chapter 14 Space Warps and Particle Systems

The Vortex warp appears as a curved-arrow icon in the plane you drag
in, with a second, perpendicular arrow indicating the axis of rotation as
well as the direction of the well. This second axis is called the drop axis.

NOTE The position of the space warp plays an important role in the results.
The vertical position affects the shape of the vortex, and the horizontal
position determines its location. If you want the particles to spiral around the
particle emitter, place both at the same location.

Forces | 2703

Interface

Timing group

Time On/Time Off The frame numbers at which the space warp becomes
active and becomes inactive.

2704 | Chapter 14 Space Warps and Particle Systems

Vortex Shape group

Taper Length Controls the length of the vortex, as well as its shape. Lower
settings give you a "tighter" vortex, while higher settings give you a "looser"
vortex. Default=100.0.

Taper Curve Controls the shape of the vortex. Low values create a vortex
with a wide, flared mouth, while high values create a vortex with nearly vertical
sides. Default=1.0. Range=1.0 to 4.0.

Capture and Motion group

This group contains basic settings for Axial Drop, Orbital Speed, and Radial
Pull, with Range, Falloff, and Damping modifiers for each.

Unlimited Range When on, Vortex exerts full damping strength over an
unlimited range. When off, the Range and Falloff settings take effect.

Axial Drop Specifies how quickly particles move in the direction of the drop
axis.

Range The distance from the center of the Vortex icon, in system units, at
which Axial Damping has its full effect. Takes effect only when Unlimited
Range is turned off.

Falloff Specifies the distance beyond the Axial Range within which Axial
Damping is applied. Axial Damping is strongest at the Range distance, decreases
linearly out to the limit of the Axial Falloff, and has no effect beyond that.
Takes effect only when Unlimited Range is turned off.

Damping Controls the degree to which particle motion parallel to the drop
axis is restrained per frame. Default=5.0. Range=0 to 100.

For subtle effects, use values of less than 10%. For more overt effects, try using
higher values that increase to 100% over the course of a few frames.

Orbital Speed Specifies how quickly the particles rotate.

Range The distance from the center of the Vortex icon, in system units, at

which Orbital Damping has its full effect. Takes effect only when Unlimited
Range is turned off.

Falloff Specifies the distance beyond the Orbital Range within which Orbital
Damping is applied. Orbital Damping is strongest at the Range distance,
decreases linearly out to the limit of the Orbital Falloff, and has no effect
beyond that. Takes effect only when Unlimited Range is turned off.

Forces | 2705

Damping Controls the degree to which orbital particle motion is restrained
per frame. Smaller values produce a wide spiral, while larger values produce
a thin spiral. Default=5.0. Range=0 to 100.

Radial Pull Specifies the distance from the drop axis at which the particles
rotate.

Range The distance from the center of the Vortex icon, in system units, at
which Radial Damping has its full effect. Takes effect only when Unlimited
Range is turned off.

Falloff Specifies the distance beyond the Radial Range within which Radial
Damping is applied. Radial Damping is strongest at the Range distance,
decreases linearly out to the limit of the Radial Falloff, and has no effect beyond
that. Takes effect only when Unlimited Range is turned off.

Damping Controls the degree to which Radial Pull is restrained per frame.
Default=5.0. Range=0 to 100.

CW/CCW Determines whether particles rotate clockwise or counterclockwise.

Display group

Icon Size Specifies the size of the icon.

Drag Space Warp

Create panel > Space Warps > Forces > Object Type rollout > Drag

Create menu > Space Warps > Forces > Drag

The Drag space warp is a particle motion damper that reduces particle velocity
by a specified amount within a specified range. The damping can be applied
linearly, spherically, or cylindrically. Drag is useful for simulating wind
resistance, transfers into dense media (like water), impacts with force fields,
and other, similar situations.

With each damping type, you can control the damping effect along several
vectors. The damping is also affected by particle system settings, such as speed.

NOTE To create a uniform drag effect, the default value for all directional
parameters is 5.0%.

2706 | Chapter 14 Space Warps and Particle Systems

Drag slows down a stream of particles.

Procedures

To create a Drag space warp:

1 On the Create panel, click Space Warps. Choose Forces from

the list, and then click Drag.

2 Drag in a viewport to create the space warp.

The space warp appears initially as a box within a box, indicating that
it's using the default Linear Damping mode.

3 To apply the damping spherically or cylindrically, choose Spherical

Damping or Cylindrical Damping in the command panel.

Forces | 2707

NOTE The position and orientation of the space warp plays an important
role for all three damping types.

4 Change the settings for the current damping type as necessary.

2708 | Chapter 14 Space Warps and Particle Systems

Interface

Forces | 2709

Timing group

Time On/Time Off The frame numbers at which the space warp becomes
active and becomes inactive.

Damping Characteristics group

This group lets you choose Linear Damping, Spherical Damping, or Cylindrical
Damping, plus a set of parameters for each.

Unlimited Range When on, Drag exerts full damping strength over an
unlimited range. When off, the Range and Falloff settings for the current
damping type take effect.

■ Linear Damping Motion for each particle is separated into vectors for

the space warp's local X, Y, and Z axes. The area over which damping is
exerted for each vector is an infinite plane whose thickness is determined
by the corresponding Range setting.

X Axis/Y Axis/Z Axis

Specifies the percentage of particle motion along the local Drag space warp
axis that's affected by the damping.

Range

Sets the thickness of the "range plane," or the infinite plane perpendicular
to the specified axis. Takes effect only when Unlimited Range is turned
off.

Falloff

Specifies the distance beyond the X, Y, or Z Range within which Linear
Damping is applied. Damping is strongest at the Range distance, decreases
linearly out to the limit of the Falloff, and has no effect beyond that. While
Falloff takes effect only beyond the Range, it is measured from the center
of the icon, and always has a minimum value equal to the Range value.
Takes effect only when Unlimited Range is turned off.

■ Spherical Damping When Drag operates in Spherical Damping mode,

its icon is a sphere within a sphere. Particle motion is broken up into radial
and tangential vectors. Damping is applied for each vector within a
spherical volume whose radius is set by the Range setting, when Unlimited
Range is off.

Radial/Tangential

Radial specifies the percentage of particle motion toward or away from the
center of the Drag icon that's affected by the damping. Tangential specifies
the percentage of particle motion across the body of the Drag icon that's
affected by the damping.

2710 | Chapter 14 Space Warps and Particle Systems

Range

Specifies the distance from the center of the Drag icon, in system units,
within which damping is in full effect. Takes effect only when Unlimited
Range is turned off.

Falloff

Specifies the distance beyond the Radial/Tangential Range within which
Linear Damping is applied. Damping is strongest at the Range distance,
decreases linearly out to the limit of the Falloff, and has no effect beyond
that. While Falloff takes effect only beyond the Range, it is measured from
the center of the icon, and always has a minimum value equal to the Range
value. Takes effect only when Unlimited Range is turned off.

■ Cylindrical Damping When Drag operates in Spherical Cylindrical mode,

its icon is a cylinder within a cylinder. Particle motion is broken up into
radial, tangential, and axial vectors. Damping is applied within a spherical
volume for the radial and tangential vectors and on a planar basis for the
axial vector.

Radial/Tangential/Axial

Damping controls the percentage of particle motion toward or away from
the center of the circular portion of the icon (Radial), across the radial
vector (Tangential), or along the length of the icon's long axis (Axial) that's
affected by the damping, on a per-frame basis.

Range

Specifies the distance from the center of the Drag icon, in system units,
within which Radial and Axial damping are in full effect. Range also
specifies the thickness of the infinite plane that governs the range of Axial
damping. Takes effect only when Unlimited Range is turned off.

Falloff

Specifies the distance beyond the Radial/Tangential/Axial Range within
which Linear Damping is applied. Damping is strongest at the Range
distance, decreases linearly out to the limit of the Falloff, and has no effect
beyond that. While Falloff takes effect only beyond the Range, it is
measured from the center of the icon, and always has a minimum value
equal to the Range value. Takes effect only when Unlimited Range is turned
off.

Display group

Icon Size Specifies the size of the icon.

Forces | 2711

PBomb Space Warp

Create panel > Space Warps > Forces > Object Type rollout > PBomb

Create menu > Space Warps > Forces > PBomb

The PBomb space warp creates an impulse wave to blow up a particle system,
as distinguished from the Bomb space warp on page 2789, which blows up
geometry. The PBomb is particularly well suited to the Particle Array (PArray)
system with Particle Types set to Object Fragments. This space warp also applies
an impulse as a dynamics effect.

The general usage is as follows:

■ Create a particle system (recommended: a PArray system on page 3042 set

to Object Fragments).

■ Create a PBomb and use Bind to Space Warp on page 2691 to bind it

to a non-event-driven particle system. Be sure to bind the PBomb to the
particle system and not to the distribution object. Or, if using Particle Flow,
use a Force operator on page 2946 to apply the space warp to the particle
system.

■ Adjust the parameters of both the PBomb and the particle system.

Right: PBomb viewport icon

2712 | Chapter 14 Space Warps and Particle Systems

Above: PArray particle system

Below: Torus knot used as the PArray's distribution object

Effect of blowing up the torus knot

Procedures

Example: To use PBomb with PArray:

You can use the Particle Bomb bound to a Particle Array to blow an object
into fragments. The following steps demonstrate the basic setup.

Begin by binding a particle array to an object, and setting parameters.

1 Create the object you want to blow up.

2 Create a PArray and use Pick Object to assign the object to blow up as

the PArray object-based emitter.

3 In the Basic Parameters rollout > Viewport Display group, choose Mesh

to display the fragments as mesh objects in the viewports.

Forces | 2713

4 On the Particle Generation rollout of PArray, set Speed and Divergence

to 0.0. This prevents PArray from moving the particles, letting PBomb
do the work.

5 On the Particle Generation rollout, set Life to the length of the active

time segment, so that the fragments appear during the entire animation.

6 In the Particle Type rollout > Particle Types group, choose Object

Fragments. In the Object Fragment Controls group, choose Number of
Chunks, and set the Minimum to about 50, depending on your
distribution object and the effect you want.

Now create a particle bomb, and bind it to the particle array.

1 In the Space Warps panel > Particles & Dynamics category, click the

PBomb button and drag in a viewport to create the PBomb icon.

2 Use Bind to Space Warp to bind the PArray icon to the PBomb icon.

(Don't bind the distribution object by mistake.)

3 Select the PBomb icon and move to the Modify panel.

4 In the Explosion Parameters group, set Blast Symmetry to Spherical, Start

Time to 10, Duration to 1, and Strength to 1.0. Choose Linear, if it's not
already chosen.

5 Drag the time slider between frames 9 and 20 to see the effect.

6 Go to frame 12 and try out various settings. Notice that increasing

Strength expands the explosion effect at the current frame. If you decrease
Range enough, the bomb no longer affects all or part of the object
(depending on the placement of the PBomb icon). Test the three Blast
Symmetry settings by placing the bomb in the center of the object and
then seeing the different blast patterns.

Once you get an explosive effect you like, you can return to the PArray settings,
add spin or thickness to the fragments, and so on.

2714 | Chapter 14 Space Warps and Particle Systems

Interface

Blast Symmetry group

These options specify the shape, or pattern of the blast effect.

Spherical The blast force radiates outward from the PBomb icon in all
directions. The icon looks like a spherical anarchist's bomb.

Cylindrical The blast force radiates outward from and normal to the central
axis, or core of the cylindrical icon. The icon looks like a stick of dynamite
with a fuse.

Planar The blast force radiates both up and down, perpendicular to the plane
of the planar icon. The icon looks like a plane with arrows pointing up and
down along the direction of the blast force.

Chaos The blast forces vary for each particle or each frame, an effect similar
to Brownian motion, with a rate of change in the direction of force equal to

Forces | 2715

the rendering interval rate. Note: This setting is effective only when the
Duration spinner is set to 0.

Explosion Parameters group

Start Time The frame number at which the impulse forces are first applied to
the particles.

Duration The number of frames, beyond the first, over which the forces are
applied. This value should typically be a small number, such as between 0 and

3.

Strength The change in velocity along the blast vector, in units per frame.
Increasing Strength increases the speed with which the particles are blown
away from the bomb icon.

Unlimited Range The effects of the bomb icon reach all bound particles
throughout the scene. This option ignores the Range setting (which specifies
the distance of the PBomb effect).

Linear The impulse forces decay linearly between the full Strength setting to
a value of 0 at the specified Range setting.

Exponential The impulse forces decay exponentially between the full Strength
setting to a value of 0 at the specified Range setting.

Range The maximum distance, in units, over which the PBomb icon affects
the bound particle system. If the Range is large enough to reach only a portion
of the particle system, only that part of the system is affected.

If you turn on Range Indicator (see following), the extent of the range is
indicated by a tri-hooped sphere. If you choose Unlimited Range, this
parameter has no effect.

Display Icon group

These options affect the visual display of the PBomb icon.

Icon Size Alters the overall size of the PBomb icon.

Range Indicator Displays a wireframe sphere that indicates the volume of

the particle bomb's influence. If you choose Unlimited Range, turning this
on has no effect.

2716 | Chapter 14 Space Warps and Particle Systems

Path Follow Space Warp

Create panel > Space Warps > Forces > Object Type rollout > Path Follow

Create menu > Space Warps > Forces > Path Follow

Particles following a spiral path

The Path Follow space warp forces particles to follow a spline path.

Procedures

To create a Path Follow space warp:

1 On the Create panel, click Space Warps. Choose Forces from

the list, then on the Object Type rollout, click Path Follow.

2 Click and drag in a viewport to define the size.

The Path Follow warp appears as a box-shaped icon containing curved
lines that indicate hypothetical paths.

To set up and use Path Follow:

1 Create a shape consisting of a single spline. (You can use shapes with

multiple splines, but the software uses only one spline for the path.)

2 Create a particle system and set its parameters to emit particles over a

range of frames.

Forces | 2717

3 On the Create panel, click Path Follow, and drag in a viewport to create

the Path Follow icon (a cube with wavy lines). The display and position
of this icon don't affect the particles.

4 On the Basic Parameters rollout, click Pick Shape Object and select the

spline you created earlier.

5 Bind the Path Follow icon to the particle system.

6 Adjust the Path Follow parameters to create the particle movement you

want.

NOTE You can further animate the particle effect by animating the spline
vertices.

TIP To adjust the position of the path or particle system while maintaining
access to the Path Follow parameters, turn on Modifier Stack rollout > Pin
Stack while the Path Follow space warp is selected.

If the particles don't follow the emitter after it's moved, then change any
PathFollow parameter, and the motion will be corrected.

2718 | Chapter 14 Space Warps and Particle Systems

Interface

Forces | 2719

Current Path group

Lets you choose the path for the particles, and specify the range of influence
of the Space Warp.

Object Displays the name of the currently assigned path.

Pick Shape Object Click this, and then click a shape in the scene to select it

as a path. You can use any shape object as a path; if you select a multiple-spline
shape, only one the lowest-number spline is used. You can also use NURBS
curves as paths.

Unlimited Range When off, the range of influence of the space warp is limited
to the value set in the Distance spinner. When on, the space warp influences
all bound particles in the scene, regardless of their distance from the path
object.

Range Specifies the range of influence when Unlimited Range is off. This is
the distance between the path object and the particle system. The position of
the Path Follow space warp's icon is ignored.

Motion Timing group

These controls affect how long particles are influenced by Path Follow.

Start Frame The frame at which Path Follow begins to influence the particles.

Travel Time The time each particle takes to traverse the path.

Variation The amount by which each particle's travel time can vary.

Last Frame The frame at which Path Follow releases the particles and no

longer influences them.

Particle Motion group

The controls in this area determine the motion of particles.

Along Offset Splines The distance between the particle system and the path
alter the effect of the particle motion. If the first vertex of the spline is at the
birthplace of the particle, the particle follows the spline path. If you move the
path away from the particle system, the particles are affected by the offset.

Along Parallel Splines Particles follow a copy of the selected path, parallel
to the particle system. In this mode, the position of the path relative to the
particle system does not matter. The orientation of the path, however, affects
the particle stream.

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Constant Speed When on, all particles travel at the same speed.

Stream Taper Causes particles to converge or diverge toward the path over

time, or to simultaneously converge and diverge. You specify the effect by
choosing Converge, Diverge, or Both (see following). This provides a tapering
effect over the length of the path.

Variation The amount by which Stream Taper can vary for each particle.

Converge When Stream Taper is greater than 0, the particles move in toward

the path as they follow the path. The effect is that the stream tapers from
larger to smaller over time.

Diverge Provides the opposite effect of Converge. The particles diverge from
the path over time.

Both Splits the particle stream, causing some particles to converge and others
to diverge.

Stream Swirl Specifies the number of turns by which particles spiral about
the path. In conjunction with Stream Taper, alters the diameter of the spiral.

Stream Swirl is generally more effective when you choose Along Offset Splines.

Variation The amount by which each particle can vary from the Spiral value.

Clockwise Particles spiral in a clockwise direction.

Counterclockwise Particles spiral in a counterclockwise direction.

Bidirectional The stream is split so that particles spiral in both directions.

Uniqueness group

Provides a seed number for unique generation of the particle pattern.

Seed Specifies the seed number for the current Path Follow.

Display Icon group

Affects the display of the Path Follow icon.

Icon Size Specifies the size of the Path Follow icon. Does not alter the Path
Follow effect.

Gravity Space Warp

Create panel > Space Warps > Forces > Object Type rollout > Gravity

Forces | 2721

Create menu > Space Warps > Forces > Gravity

Particles falling because of gravity

The Gravity space warp simulates the effect of natural gravity on particles
generated by a particle system. Gravity is directional. Particles moving in the
direction of the gravity arrow accelerate. Particles moving against the arrow
decelerate. In the case of spherical gravity, motion is toward the icon. Gravity
can also be used as an effect in dynamics simulations. See Dynamics Utility
on page 3852.

Gravity effect on snow

Procedures

To create gravity:

1 On the Create panel, click Space Warps. Choose Forces from

the list, then on the Object Type rollout, click Gravity.

2 Drag in a viewport.

2722 | Chapter 14 Space Warps and Particle Systems

The Gravity icon appears. For planar gravity (the default), the icon is a
wireframe square with a direction arrow on one side. For spherical gravity,
the icon is a wireframe sphere.

The initial direction of planar gravity is along the negative Z axis of the
construction grid that is active in the viewport where you drag. You can
rotate the gravity object to change the direction.

Interface

Force group

Strength Increasing Strength increases the effect of gravity; that is, how objects
move in relation to the Gravity icon's direction arrow. Strength less than 0.0
creates negative gravity, which repels particles moving in the same direction
and attracts particles moving in the opposite direction. When Strength is set
to 0.0, the Gravity space warp has no effect.

Decay When Decay is set to 0.0, the Gravity space warp has the same strength
throughout world space. Increasing the Decay value causes gravity strength
to diminish as distance increases from the position of the gravity warp object.
Default=0.0.

Planar Gravity effect is perpendicular to the plane of the Gravity warp object
throughout the scene.

Forces | 2723

Spherical Gravity effect is spherical, centered on the Gravity warp object.
This choice is effective for creating water fountain or planetary effects.

Display group

Range Indicators When on, and when the Decay value is greater than 0.0,
icons in the viewports indicate the range at which the force of gravity is half
the maximum value. For the Planar option, the indicators are two planes; for
use the Spherical option, the indicator is a double-hooped sphere.

Icon Size Size of the Gravity warp object icon, in active units. You set the
initial size when you drag to create the Gravity object. This value does not
change the gravity effect.

Wind Space Warp

Create panel > Space Warps > Forces > Object Type rollout > Wind

Create menu > Space Warps > Forces > Wind

Wind changing the direction of the spray of a fountain

2724 | Chapter 14 Space Warps and Particle Systems

The Wind space warp simulates the effect of wind blowing particles generated
by a particle system. Wind is directional. Particles moving in the direction of
the wind arrow accelerate. Particles moving against the arrow decelerate. In
the case of spherical wind, motion is toward or away from the icon. Wind is
similar in effect to the Gravity space warp, but has added parameters for
turbulence and other features characteristic of wind in the natural world.
Wind can also be used as an effect in dynamics simulations. See Dynamics

Utility on page 3852.

Wind effect on snow and spray

Procedures

To create wind:

1 On the Create panel, click Space Warps. Choose Forces from

the list, then on the Object Type rollout, click Wind.

2 Drag in a viewport.

The wind icon appears. For planar wind (the default), the icon is a
wireframe square with a direction arrow coming out of one side. For
spherical wind, the icon is a wireframe sphere.

The initial direction of planar wind is along the negative Z axis of the
construction grid that is active in the viewport where you drag. You can
rotate the wind object to change the direction.

Forces | 2725

Interface

Force group

These settings are comparable to the Gravity parameters.

Strength Increasing Strength increases the wind effect. Strength less than 0.0
creates a suction. It repels particles moving in the same direction and attracts
particles moving in the opposite direction. When Strength is 0.0, the Wind
warp has no effect.

Decay When Decay is set to 0.0, the Wind warp has the same strength
throughout world space. Increasing the Decay value causes wind strength to
diminish as distance increases from the position of the Wind warp object.
Default=0.0.

Planar Wind effect is perpendicular to the plane of the Wind warp object,
throughout the scene.

2726 | Chapter 14 Space Warps and Particle Systems

Spherical Wind effect is spherical, centered on the Wind warp object.

Wind group

These settings are specific to the Wind space warp.

Turbulence Causes particles to change course randomly as the wind blows
them. The greater the value, the greater the turbulence effect.

Frequency When set greater than 0.0, causes turbulence to vary periodically
over time. This subtle effect is probably not visible unless your bound particle
system generates a large number of particles.

Scale Scales the turbulence effect. When Scale is small, turbulence is smoother
and more regular. As Scale increases, turbulence grows more irregular and
wild.

Display group

Range Indicators When the Decay value is greater than zero, icons appear in
the viewports that represent the range at which the force of wind is half the
maximum value. When you use the Planar option, the indicators are two
planes; when you use the Spherical option, the indicator is a double-hooped
sphere.

Icon Size Size of the Wind warp object icon, in active units. You set the initial
Icon Size value when you drag to create the wind object. This value does not
change the wind effect.

Displace Space Warp

Create panel > Space Warps > Geometric/Deformable > Object Type rollout >
Displace

Create menu > Space Warps > Geometric/Deformable > Displace

Forces | 2727

Displace used to change the surface in the container

The Displace space warp acts as a force field to push and reshape an object's
geometry. Displace affects both geometry (deformable objects) and particle
systems. There are two basic ways to use the Displace space warp:

■ Apply the gray scale of a bitmap to generate the displacement amount.

Black areas of the 2D image are not displaced. Whiter areas push outward,
causing a 3D displacement of geometry.

■ Apply displacement directly by setting displacement Strength and Decay

values.

The Displace space warp works similarly to the Displace modifier, except that,
like all space warps, it affects world space rather than object space. Use the
Displace modifier when you need to create detailed displacement of a small
number of objects. Use the Displace space warp to displace particle systems,
a large number of geometric objects at once, or an object relative to its position
in world space.

For geometry, the detail of the displacement depends on the number of
vertices. Use the Tessellate modifier to tessellate faces you want to show in
greater detail.

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Displace space warp on a patch and the bitmap it uses

Procedures

To create a Displace space warp:

1 On the Create panel, click Space Warps. Choose

Geometric/Deformable from the list, and then on the Object Type rollout,
click Displace.

2 Drag in a viewport to create the Displace warp object, which appears as

a wireframe. Its shape depends on the active mapping parameter settings.
Regardless of the mapping, a single drag creates the space warp.

3 Bind the space warp to an appropriate object.

To assign a bitmap to a displace space warp:

1 Select the Displace warp object.

2 In the Parameters rollout > Displacement group, click the Bitmap button

(labeled "None" by default). Use the selection dialog to choose a bitmap.

3 Set the Strength value. Vary the strength of the field to see how the bitmap

displaces the object's geometry.

Forces | 2729

Interface

Displacement group

These are the basic controls for Displace space warps.

2730 | Chapter 14 Space Warps and Particle Systems

Strength When set to 0.0, the Displace warp has no effect. Values greater than

0.0 displace object geometry or particles away from the position of the Displace
space warp object. Values less than 0.0 displace geometry toward the warp.
Default=0.0

Decay By default, the Displace warp has the same strength throughout world
space. Increasing Decay causes displacement strength to diminish as distance
increases from the position of the Displace warp object. Default=0.0

Luminance Center By default, the Displace space warp centers the luminance
by using medium (50%) gray as the zero displacement value. Gray values
greater than 128 displace in the outward direction (away from the Displace
warp object) and gray values less than 128 displace in the inward direction
(toward the Displace warp object). You can adjust the default using the Center
spinner. With a Planar projection, the displaced geometry is repositioned
above or below the Planar gizmo. Default=0.5. Range=0 to 1.0.

Image group

These options let you choose a bitmap and map to use for displacement.

Bitmap (Labeled "None" by default.) Click to assign a bitmap or map from a
selection dialog. After you choose a bitmap or map, this button displays the
bitmap's name.

Remove Bitmap Click to remove the bitmap or map assignment.

Blur Increase this value to blur or soften the effect of the bitmapped

displacement.

Map group

This area contains mapping parameters for a bitmapped Displace warp. The
mapping options are comparable to those options used with mapped materials.
The four mapping modes control how the Displace warp object projects its
displacement. The warp object's orientation controls where in the scene the
displacement effect will appear on bound objects.

Planar Projects the map from a single plane.

Cylindrical Projects the map as if it were wrapped around the cylinder.

Spherical Projects the map from a sphere, with singularities at the top and

bottom of the sphere, where the bitmap edges meet at the sphere's poles.

Shrink Wrap Truncates the corners of the map and joins them all at a single
pole, creating one singularity.

Forces | 2731

Length, Width, Height Specify the dimensions of the bounding box of the
space warp gizmo. Height has no effect on planar mapping.

U/V/W Tile The number of times the bitmap repeats along the specified
dimension. The default value of 1.0 maps the bitmap once; a value of 2.0 maps
the bitmap twice, and so on. Fractional values map a fractional portion of the
bitmap in addition to copies of the whole map. For example, a value of 2.5
maps the bitmap two and one-half times.

Flip Reverses the orientation of the map along the corresponding U, V, or W
axis.

Deflectors

POmniFlect Space Warp

Create panel > Space Warps > Deflectors > Object Type rollout > POmniFlect

POmniFlect is a planar version of the omniflector type of space warp. It
provides enhanced functionality over that found in the original Deflector
space warp, including refraction and spawning capabilities.

2732 | Chapter 14 Space Warps and Particle Systems

POmniFlect viewport icon

Procedures

To create a POmniFlect space warp:

1 On the Create panel, click Space Warps. Choose Deflectors

from the list, then on the Object Type rollout, click POmniFlect.

2 Drag in a viewport to create the planar icon.

NOTE Because particles bounce off the icon, the size of the icon affects

particle deflection.

3 Apply the deflector to the particle system using the appropriate method:

■ If using Particle Flow on page 2795, specify the deflector in the Collision

test on page 2960 or Collision Spawn test on page 2964 parameters.

■ If using a non-event-driven particle system on page 3002, bind

on page 2691 the particle system to the deflector icon.

Deflectors | 2733

4 Position the POmniFlect icon to interrupt the particle stream.

5 Adjust the POmniFlect parameters as necessary.

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Interface

Deflectors | 2735

Timing group

The two spinners specify the start frame and end frame of the deflection effect.

Time On/Off Time On specifies the frame at which the deflection begins,
and Time Off specifies the frame at which the deflection ends.

Reflection group

These options affect the reflection of particles from the space warp. The
POmniFlect can reflect or refract particles, or perform a combination of the
two.

Reflects Specifies the percentage of particles to be reflected by the POmniFlect.
See also Refracts, later in this topic, for methods of combining the two effects.

Bounce This is a multiplier that specifies how much of the initial speed of
the particle is maintained after collision with the POmniFlect. Using the default
setting of 1.0 causes the particle to rebound with the same speed as it collides.
A real-world effect would usually be less than 1.0. For a “flubber” effect, set
greater than 1.0.

Variation Specifies the variation of Bounce applied to the range of particles.
For example, a Variation of 50% applied to a Bounce setting of 1.0 would
result in randomly applied Bounce values ranging from 0.5 to 1.5.

Chaos Applies a random variation to the bounce angle. When set to 0.0 (no
chaos), all particles bounce off the POmniFlect surface perfectly (like banking
pool balls). A non-zero setting causes the deflected particles to scatter.

Refraction group

These settings are similar to those in the Reflection group, but these affect the
refraction of particles as they pass through the POmniFlect, causing the direction
of the particles to change.

Refracts Specifies the percentage of particles not already reflected that will be
refracted by the POmniFlect.

NOTE The Refracts value affects only those particles not already reflected because
the reflected particles are processed before the refracted particles. Thus, if you set
Reflects to 50% and Refracts to 50%, you would not get a 50/50 split of particles.
Rather, half the particles would be reflected, and then half the remainder (25% of
the total) would be refracted. The remaining particles either pass through without
being refracted or are passed on to Spawn Effects.

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To get a 50/50 split of reflection and refraction, set Reflects to 50% and Refracts
to 100%.

Pass Vel Specifies how much of a particle’s initial speed is maintained after
passing through the POmniFlect. The default setting of 1 retains the initial
speed is retained, so there’s no change. A setting of 0.5 reduces the speed by
half.

Variation Specifies the variation of Pass Velocity applied to the range of
particles.

Distortion Controls the angle of refraction. A value of 0 means there’s no
refraction. A value of 100% sets the angle of the particles to be parallel with
the POmniFlect surface. A value of −100% sets the angle perpendicular to the
surface. The Distortion effect is reversed when particles strike the POmniFlect
from the back side.

NOTE Distortion and Refraction do not work properly when particles strike the
POmniFlect surface at exactly 90 degrees. In this case, any positive Distortion
settings cause a scattering of particles, while negative values have no effect.

Variation Specifies a range of variation of the Distortion effect.

Diffusion Applies a diffusion effect to the refraction by randomly modifying

each particle’s Distortion angle by the Diffusion angle. This effectively scatters
the particles into a hollow cone.

Variation Specifies a range of variation of the Diffusion value.

Common group

Friction The amount by which particles are slowed as they move along the
deflector surface. A value of 0% means they're not slowed at all. A value of
50% means they're slowed to half their original speed. A value of 100% means
they stop moving when they strike the surface. Default=0%. Range=0% to
100%.

TIP To have particles slide along a deflector surface, set Bounce to 0. Also, unless
influenced by a force such as Wind or Gravity, particles meant to slide should strike
the surface at an angle other than 90 degrees.

Inherit Vel (Velocity Inheritance) Determines how much of a moving
POmniFlect’s speed is applied to reflected or refracted particles.

Deflectors | 2737

For example, if Inherit Vel is 1.0, particles with no motion that are hit by a
moving PomniFlect inherit the speed of the POmniFlect at the point of
collision.

Spawn Effects Only group

These settings affect only particles set to Spawn On Collision that do not either
reflect or refract from the omniflector. See Particle Spawn Rollout on page 3069.
The Spawns percentage spinner works like the Reflects and Refracts percentage
spinners, but is the third in line to be processed. Thus, if either Reflects or
Refracts are set to 100%, no particles are affected by these settings. Note also
that reflective or refractive particles spawn upon collision, regardless of the
settings in this group.

Spawns Specifies the percentage of particles that can use spawn effects.

Pass Vel Specifies how much of the particle’s initial speed is maintained after

passing through the POmniFlect.

Variation Specifies the variation of the Pass Velocity setting applied to the
range of particles.

Display Icon group

Width/Height Specify the width and height of the POmniFlect icon. This is
for display purposes only and does not influence the deflector effect.

PDynaFlect Space Warp

Create panel > Space Warps > Deflectors > Object Type rollout > PDynaFlect

PDynaFlect (planar dynamics deflector) is a planar version of the dynaflector,
a special class of space warp that lets particles affect objects in a dynamics
situation. For example, if you want a stream of particles to strike an object
and knock it over, like the stream from a firehose striking a stack of boxes,
use a dynaflector.

NOTE You use dynaflectors in the same way as omniflectors; that is, you can use
them as deflectors alone, with no dynamics simulation. Because they take physics
into account, dynaflectors are slower than omniflectors. Therefore, it is
recommended that you use dynaflectors only when a dynamics simulation is
involved.

2738 | Chapter 14 Space Warps and Particle Systems

PDynaflect viewport icon

Procedures

Many dynaflector parameters are the same as those for omniflectors. However,
the procedure of associating the dynaflector with both the particle system
and the object to be affected is more complex than the simple binding used
by omniflector.

To create a particle/dynamics system:

1 Create or load a scene containing a non-event-driven particle system on

page 3002 and an object to be affected by the particles (hereafter called "the
object"). Position and orient the two as desired so that the particles strike
the object.

■ The icon for the particle system must be visible in at least one

non-disabled viewport.

■ On the Basic Parameters rollout of the particle system, set Percentage

of Particles to 100%. Otherwise, only those particles displayed in the
viewport will be calculated.

Deflectors | 2739

2 On the Create panel, click Space Warps. Choose Deflectors

from the drop-down list, and then click one of the dynaflector buttons
(PDynaFlect, SDynaFlect, or UDynaFlect). Drag in a viewport to create
the deflector.

3 Do either of the following:

■ If using a PDynaFlect or SDynaFlect, position the space warp icon

where the particles strike (or will strike) the object. Resize and orient
it as needed.

Also, link the PDynaFlect or SDynaFlect as a child of the object.
This step isn't absolutely necessary, but allows the deflector to follow
the object as it moves.

■ If using a UDynaFlect, go to the Modify panel > Parameters rollout,

click the Pick Object button, and then select the object. The position
of the space warp icon doesn't matter, and it's not necessary to link
the two.

4 Bind the particle system to the dynaflector using the toolbar Bind

to Space Warp button on page 2691.

5 Go to the Utilities panel and open the Dynamics utility.

6 On the Dynamics rollout, click New to create a new simulation.

7 Click Edit Object List, and add the object to the dynamics simulation.

8 Click Edit Object. On the Edit Object dialog, click Assign Object Effects

and assign the dynaflector to the object.

9 On the Dynamics rollout, turn on the Update Display w/Solve check box

above the Solve button.

10 Solve the simulation.

2740 | Chapter 14 Space Warps and Particle Systems

Interface

Timing group

The two spinners specify the start frame and end frame of the deflection effect.

Deflectors | 2741

Time On/Off Time On specifies the frame at which the deflection begins,
and Time Off specifies the frame at which the deflection ends.

Particle Bounce group

These settings affect the reflection of particles from the space warp.

Reflects Specifies the percentage of particles to be reflected by the PDynaFlect.

This affects both the particles and the dynamics reaction of the object struck
by the particles. The more particles that strike the affected object, the more
force applied to that object. If set to 0.0, the particles have no effect on the
object.

Bounce This is a multiplier that specifies how much of the initial speed of
the particle is maintained after collision with the PDynaFlect.

Using the default setting of 1.0 causes the particle to rebound with the same
speed as it collides. A real-world effect would usually be less than 1.0. For a
"flubber" effect, set greater than 1.0.

Variation Specifies the variation of Bounce applied to the range of particles.

For example, a Variation setting of 50% applied to a Bounce setting of 1.0
would result in randomly applied Bounce values ranging from 0.5 to 1.5.

Chaos Applies a random variation to the bounce angle.

When you set Chaos to 0.0 (no chaos), all particles bounce off the PDynaFlect
surface perfectly (like banking pool balls). A non-zero setting causes the
deflected particles to scatter.

Friction The amount by which particles are slowed as they move along the
deflector surface. A value of 0% means they're not slowed at all. A value of
50% means they're slowed to half their original speed. A value of 100% means
they stop moving when they strike the surface. Default=0%. Range=0% to
100%.

TIP To have particles slide along a deflector surface, set Bounce to 0. Also, unless
influenced by a force such as Wind or Gravity, particles meant to slide should strike
the surface at an angle other than 90 degrees.

Inherit Vel (Velocity Inheritance) Determines how much of a moving
PDynaFlect’s speed is applied to reflected or refracted particles.

For example, if Inherit Vel is 1.0, particles with no motion that are hit by a
moving PDynaFlect inherit the speed of the PDynaFlect at the point of
collision.

2742 | Chapter 14 Space Warps and Particle Systems

Physical Properties group

These options let you set the mass of each particle.

Mass Specifies the mass based on the chosen unit.

gram One gram equals 1/1000 kg or 22/1000 Lbm at a gravity of 1.0.

Kg One kg (kilogram) equals 1000 grams or 2.2 Lbm at a gravity of 1.0.

Lbm One Lbm (pounds-mass) equals 5/11 kg or 454 5/11 grams at a gravity

of 1.0. (Pounds-mass, the amount of mass in one pound of weight, is dependent
on gravity. For pounds-mass values at a gravity other than 1.0, multiply the
pounds-mass value by the gravity factor.)

Display Icon group

Width/Height Specify the width and height of the PDynaFlect icon. This is
for display purposes only and does not influence the deflector effect.

SOmniFlect Space Warp

Create panel > Space Warps > Deflectors > Object Type rollout > SOmniFlect

SOmniFlect is the spherical version of the omniflector type of space warp. It
provides more options than the original SDeflector. Most settings are the same
as those in POmniFlect on page 2732. The difference is that this space warp
provides a spherical deflection surface rather than the planar surface. The only
settings that are different are in the Display Icon area, in which you set the
Radius, instead of the Width and Height.

Deflectors | 2743

NOTE Opposite sides of the deflectors reverse the distortion effect. Thus, a refracted
particle passing through the SOmniFlect hits its outside surface first, and then its
inside surface. A positive Distortion value warps the particles toward the
perpendicular; then, as the particles pass through the inside surface, the same
positive Distortion value warps them toward the parallel.

SOmniFlect viewport icon

Procedures

To create an SOmniFlect space warp:

1 On the Create panel, click Space Warps. Choose Deflectors

from the list, then on the Object Type rollout, click SOmniFlect.

2 Drag in a viewport to create the spherical icon.

NOTE Because particles bounce off the icon, the size of the icon affects

particle deflection.

2744 | Chapter 14 Space Warps and Particle Systems

3 Apply the deflector to the particle system using the appropriate method:

■ If using Particle Flow on page 2795, specify the deflector in the Collision

test on page 2960 or Collision Spawn test on page 2964 parameters.

■ If using a non-event-driven particle system on page 3002, bind

on page 2691 the particle system to the deflector icon.

4 Position the SOmniFlect icon to interrupt the particle stream.

5 Adjust the SOmniFlect parameters as necessary.

SDynaFlect Space Warp

Create panel > Space Warps > Deflectors > Object Type rollout > SDynaFlect

The SDynaFlect space warp is a spherical dynamics deflector. It’s like the

PDynaFlect on page 2738 warp, except that it’s spherical, and its Display Icon

spinner specifies the icon's Radius value.

SDynaFlect viewport icon

Deflectors | 2745

UOmniFlect Space Warp

Create panel > Space Warps > Deflectors > Object Type rollout > UOmniFlect

UOmniFlect, the universal omniflector, provides more options than the original
UDeflector. This space warp lets you use any other geometric object as a particle
deflector. The deflections are face accurate, so the geometry can be static,
animated, or even morphing or otherwise deforming over time.

NOTE Some particle “leakage” can occur with this deflector, particularly when
you use many particles and a complex deflector object. To avoid this, perform a
test render to check for leaking particles, and then add POmniFlects to catch the
strays.

UOmniFlect viewport icon

2746 | Chapter 14 Space Warps and Particle Systems

Procedures

To use the UOmniFlect space warp:

To use a universal omniflector, you need a minimum of three objects in the
scene:

1 The particle system

2 The UOmniFlect space warp

3 The object used as the deflector

4 Add or select an object used as the deflector.

5 Create a particle system whose particles intersect the deflector object.

6 On the Create panel, click Space Warps. Choose Deflectors

from the list, and then click UOmniFlect.

7 Click and drag in a viewport to place the space warp icon.

NOTE The size and position of the UOmniFlect icon do not alter the effect.

8 Apply the deflector to the particle system using the appropriate method:

■ If using Particle Flow on page 2795, specify the deflector in the Collision

test on page 2960 or Collision Spawn test on page 2964 parameters.

■ If using a non-event-driven particle system on page 3002, bind

on page 2691 the particle system to the deflector icon.

9 On the Modify panel > Parameters rollout > Object-Based

OmniFlector group, click Pick Object, and then select the object to use
as a deflector.

10 Adjust the particle system and UOmniFlect parameters as necessary.

Deflectors | 2747

Interface

Parameters rollout

The settings for the UOmniFlect are the same as those for POmniFlect on page
2732, with the following additions:

Object-Based OmniFlector group

Lets you choose the object to use as a deflector.

Item Displays the name of the selected object.

Pick Object Click this, and then select any renderable object to use as a

deflector.

Display Icon group

Icon Size Specifies the size of one side of the square UOmniFlect icon.

UDynaFlect Space Warp

Create panel > Space Warps > Deflectors > Object Type rollout > UDynaFlect

The UDynaFlect space warp is a universal dynamics deflector that lets you use
the surface of any object as both the particles deflector and the surface that
reacts dynamically to the particle impact.

The procedures and options for using UDynaFlect are the same as for

PDynaFlect on page 2738, with the following changes and additions.

2748 | Chapter 14 Space Warps and Particle Systems

UDynaFlect viewport icon

NOTE When you use UDynaFlect, you must indicate the object to be affected

with the Pick Object button. Linking is not necessary.

Deflectors | 2749

Interface

2750 | Chapter 14 Space Warps and Particle Systems

Object-Based DynaFlector group

Lets you choose the object to use as a deflector.

Item Displays the name of the selected object.

Pick Object Click this, and then select any renderable object to use as a

deflector.

Display Icon group

Icon Size Specifies the size of the UDynaFlect icon.

SDeflector Space Warp

Create panel > Space Warps > Deflectors > Object Type rollout > SDeflector

Create menu > Space Warps > Deflectors > SDeflector

The SDeflector space warp serves as a spherical deflector of particles.

SDeflector viewport icon (with particle system on the left)

Deflectors | 2751

SDeflector repelling particles

Procedures

To create an SDeflector:

1 On the Create panel, click Space Warps. Choose Deflectors

from the list, then on the Object Type rollout, click SDeflector.

2 Drag in a viewport to create the spherical icon.

NOTE Because particles bounce off the perimeter of the spherical icon, the

size of the icon affects particle deflection.

3 Apply the deflector to the particle system using the appropriate method:

■ If using Particle Flow on page 2795, specify the deflector in the Collision

test on page 2960 or Collision Spawn test on page 2964 parameters.

■ If using a non-event-driven particle system on page 3002, bind

on page 2691 the particle system to the deflector icon.

4 Position the SDeflector icon to interrupt the particle stream.

2752 | Chapter 14 Space Warps and Particle Systems

5 Adjust the SDeflector parameters as necessary.

Interface

Particle Bounce group

These settings determine how the deflector affects the bound particles.

Bounce Determines the speed with which particles bounce off the deflector.
At 1.0, the particles bounce at the same speed as they approach. At 0, they
don't deflect at all.

Variation The amount by which each particle can vary from the Bounce
setting.

Chaos The amount of variation from the perfect angle of reflection (found
when Chaos is set to 0.0). 100% induces a variation in reflection angle of up
to 90 degrees

Friction The amount by which particles are slowed as they move along the
deflector surface. A value of 0% means they're not slowed at all. A value of
50% means they're slowed to half their original speed. A value of 100% means
they stop moving when they strike the surface. Default=0%. Range=0% to
100%.

Deflectors | 2753

TIP To have particles slide along a deflector surface, set Bounce to 0. Also, unless
influenced by a force such as Wind or Gravity, particles meant to slide should strike
the surface at an angle other than 90 degrees.

Inherit Vel (Velocity Inheritance) When the value is greater than 0, the motion
of the deflector affects particles as well as the other settings. For example, to
animate the SDeflector passing through a passive array of particles, turn up
this value to affect the particles.

Display Icon group

This option affects the display of the icon.

Diameter Specifies the diameter of the SDeflector icon. This setting also alters
the effect of the deflection, because particles bounce off the perimeter of the
icon. The scale of the icon also affects the particles.

UDeflector Space Warp

Create panel > Space Warps > Deflectors > Object Type rollout > UDeflector

Create menu > Space Warps > Deflectors > UDeflector

2754 | Chapter 14 Space Warps and Particle Systems

Particles scatter when they strike a UDeflector object

The UDeflector is a universal deflector that lets you use any object as a particle
deflector.

Procedures

To create a UDeflector:

1 On the Create panel, click Space Warps. Choose Deflectors

from the list, then on the Object Type rollout, click UDeflector.

2 In a viewport, drag out a rectangle to add a UDeflector warp to the scene.

3 On the command panel, click the Pick Object button and select an object

to be a particle deflector.

Deflectors | 2755

4 Apply the deflector to the particle system using the appropriate method:

■ If using Particle Flow on page 2795, specify the deflector in the Collision

test on page 2960 or Collision Spawn test on page 2964 parameters.

■ If using a non-event-driven particle system on page 3002, bind

on page 2691 the particle system to the deflector icon.

5 Position the UDeflector icon to interrupt the particle stream.

6 Adjust the UDeflector parameters as necessary.

Interface

Object-Based Deflector group

Specifies the object to use as a deflector.

2756 | Chapter 14 Space Warps and Particle Systems

Item Displays the name of the selected object.

Pick Object Click this, and then click any renderable mesh object to be used

as a deflector.

Particle Bounce group

Bounce Determines the speed with which particles bounce off the deflector.
At 1.0, the particles bounce at the same speed as they approach. At 0, they
don't deflect at all.

Variation The amount by which each particle can vary from the Bounce
setting.

Chaos The amount of variation from the perfect angle of reflection (found
when Chaos is set to 0.0). 100% induces a variation in reflection angle of up
to 90 degrees.

Friction The amount by which particles are slowed as they move along the
deflector surface. A value of 0% means they're not slowed at all. A value of
50% means they're slowed to half their original speed. A value of 100% means
they stop moving when they strike the surface. Default=0%. Range=0% to
100%.

TIP To have particles slide along a deflector surface, set Bounce to 0. Also, unless
influenced by a force such as Wind or Gravity, particles meant to slide should strike
the surface at an angle other than 90 degrees.

Inherit Vel (Velocity Inheritance) When greater than 0, the motion of the
deflector affects particles as well as the other settings. For example, to animate
the SDeflector passing through a passive array of particles, turn up this value
to affect the particles.

Display Icon group

Icon Size This spinner displays and lets you change the size of the icon.

Deflector Space Warp

Create panel > Space Warps > Deflectors > Object Type rollout > Deflector

Create menu > Space Warps > Deflectors > Deflector

Deflectors | 2757

Two streams of particles striking two deflectors

The Deflector space warp acts as a planar shield to repel the particles generated
by a particle system. For example, you can use Deflector to simulate pavement
being struck by rain. You can combine a Deflector space warp with a Gravity
space warp to produce waterfall and fountain effects.

See also:

■ SDeflector Space Warp on page 2751

■ UDeflector Space Warp on page 2754

Procedures

To create a deflector:

1 On the Create panel, click Space Warps. Choose Deflectors

from the list, then on the Object Type rollout, click Deflector.

2 Drag in a viewport to define the deflection area.

2758 | Chapter 14 Space Warps and Particle Systems

The deflector appears as a wireframe rectangle.

3 Apply the deflector to the particle system using the appropriate method:

■ If using Particle Flow on page 2795, specify the deflector in the Collision

test on page 2960 or Collision Spawn test on page 2964 parameters.

■ If using a non-event-driven particle system on page 3002, bind

on page 2691 the particle system to the deflector icon.

Interface

The deflector's effect is controlled mainly by its size and orientation in the
scene, relative to the particle system that is bound to it. You can also adjust
how strongly the deflector deflects particles.

Bounce Controls the speed at which particles bounce off the deflector. At a
setting of 1.0, particles bounce off the deflector at the same speed they struck
it. At 0.0, particles do not bounce at all. At values between 0.0 and 1.0, particles
bounce off the deflector at a speed reduced from their initial speed. At values
greater than 1.0, particles bounce off the deflector at a speed greater than their
initial speed. Default=1.0.

Deflectors | 2759

Variation The amount by which each particle can vary from the Bounce
setting.

Chaos The amount of variation from the perfect angle of reflection (found
when Chaos is set to 0.0). 100% induces a variation in reflection angle of up
to 90 degrees

Friction The amount by which particles are slowed as they move along the
deflector surface. A value of 0% means they're not slowed at all. A value of
50% means they're slowed to half their original speed. A value of 100% means
they stop moving when they strike the surface. Default=0%. Range=0% to
100%.

TIP To have particles slide along a deflector surface, set Bounce to 0. Also, unless
influenced by a force such as Wind or Gravity, particles meant to slide should strike
the surface at an angle other than 90 degrees.

Inherit Vel (Velocity Inheritance) When the value is greater than 0, the motion
of the deflector affects particles as well as the other settings. For example, if
you want an animated SDeflector passing through an array of particles to
affect the particles, turn up this value.

Width Sets the deflector's width.

Length Sets the deflector's length.

Geometric/Deformable

FFD(Box) Space Warp

Create panel > Space Warps > Geometric/Deformable > Object Type rollout >
FFD(Box)

Create menu > Space Warps > Geometric/Deformable > FFD(Box)

Free-form deformations (FFDs) provide a method of deforming an object by
adjusting the control points of a lattice. The offset position of the control
points to the original lattice source volume causes the distortion of the affected
object.

The FFD(Box) space warp is a box-shaped lattice FFD object similar to the
original FFD modifiers. This FFD is available as both an object modifier and
a space warp. For information on the object-modifier version, see FFD

(Box/Cylinder) Modifiers on page 1460.

2760 | Chapter 14 Space Warps and Particle Systems

You create FFD space warps as separate objects similarly to the way you create
standard primitives: by dragging the mouse in the viewport. The result is a
lattice of control points. The source lattice of an FFD modifier is fitted to the
geometry it's assigned to in the stack. This might be a whole object or a
sub-object selection of faces or vertices.

Because FFD space warps are separate objects, they carry their own adjustable
dimension parameters among the creation parameters.

You can apply object modifiers to space warp objects. For example, you can
use the Linked XForm modifier with a space-warp FFD.

Geometric/Deformable | 2761

Object and object surrounded by an FFD lattice

2762 | Chapter 14 Space Warps and Particle Systems

Moving control points in the lattice deforms the object.

Procedures

To use the FFD(box) space warp:

1 On the Create panel, click Space Warps. Choose

Geometric/Deformable from the list, then on the Object Type rollout,
click FFD(Box).

2 Drag in a viewport to create the base. Release the mouse button, and then

move the mouse to define the height of the FFD lattice. Click to finish
the lattice.

3 Bind the lattice to the object you want to deform.

4 Determine the relative placement of the lattice to the object.

If the lattice is to be outside of the object, turn on All Vertices. To affect
only those vertices inside the lattice, choose Only In Volume, and position
the lattice accordingly.

Geometric/Deformable | 2763

5 In the modifier stack display, choose Control Points as the

sub-object level for FFD(box).

6 Adjust the control points.

NOTE The distortion effect of an FFD modifier is based on the positional

offset of the control points from their original positions in the source volume.
If you don't move control points, there is no effect on the target object. Keep
this in mind when using space-warp version of the FFD.

If you're using the Deform group > All Vertices option, once you've distorted
the object you can set the Falloff value to adjust how much the lattice affects
the object, based on distance. This is particularly useful if the lattice is animated
to approach or move away from the target object. When Falloff is set to 0, all
the vertices are affected, regardless of distance.

NOTE When you're at the base-parameters level of an FFD modifier in the Stack,
the Show End Result button is turned off and spring-loaded, as it is in an Edit Mesh
modifier.

2764 | Chapter 14 Space Warps and Particle Systems

Interface

Geometric/Deformable | 2765

This rollout lets you set the size and resolution of the lattice, and how it
displays and deforms.

Dimensions group

These options let you adjust the unit dimensions of the source volume, and
specify the number of control points in the lattice. Note that the point
dimensions are displayed beside the modifier name in the Stack list.

Length, Width, Height These three spinners display and let you adjust the
length, width, and height of the lattice. To create the space warp, you drag
the mouse in the same way that you would to create a standard Box primitive.
Note that these spinners don't exist in the object-modifier version of the FFD.

Label Displays the current number of controls points in the lattice (for
example: 4x4x4).

Set Number of Points Displays a dialog containing three spinners labeled
Length, Width, and Height, plus OK/Cancel buttons. Specify the number of
control points you want in the lattice, and then click OK to make the change.

NOTE Make changes to the dimensions before you adjust the positions of the
lattice control points. When you change the number of control points with this
dialog, any adjustments you've already made to the control points are lost;
however, you can undo this use of the dialog.

Display group

These options affect the display of the FFD in the viewports.

Lattice When turned on, lines are drawn connecting the control points to
make a grid. Although viewports can become cluttered when these extra lines
are drawn, they help to visualize the lattice.

Source Volume When on, the control points and lattice are displayed in their
unmodified state. This display is helpful when you're adjusting the source
volume to affect specific vertices that lie within or without it. See the All
Vertices and Only in Volume options, later in this topic.

Deform group

These options provide controls that specify which vertices are affected by the
FFD.

Only In Volume Only vertices that lie inside the source volume are deformed.
Vertices outside the source volume are not affected.

2766 | Chapter 14 Space Warps and Particle Systems

All Vertices All vertices are deformed regardless of whether they lie inside or
outside the source volume, depending on the value in the Falloff spinner. The
deformation outside the volume is a continuous extrapolation of the
deformation inside the volume. The deformation can be extreme for points
far away from the source lattice.

Falloff This spinner, enabled only when you choose All Vertices, determines
the distance from the lattice that the FFD effect will decrease to zero. When
this spinner is set to 0, it's effectively turned off, and there is no falloff; that
is, all vertices are affected regardless of their distance from the lattice. The
units of the Falloff parameter are specified relative to the size of the lattice: A
falloff of 1 means that the effect will go to 0 for points that are a lattice
width/length/height away from the lattice (depending on which side they are
on).

Tension/Continuity Lets you adjust the tension and continuity of the
deformation splines. Although you can't see the splines in an FFD, the lattice
and control points represent the structure that controls the splines. As you
adjust the control points, you alter the splines (which move through each
point). The splines, in turn, deform the geometry of the object. By altering
the tension and continuity of the splines, you alter their effect on the object.

Selection group

These options provide additional methods of selecting the control points. You
can toggle the state of any combination of the three buttons to select in one,
two, or three dimensions at once.

All X, All Y, All Z When one of these buttons is on and you select a control
point, all control points along the local dimension specified by the button
are selected as well. By turning on two buttons, you can select all control
points in two dimensions.

About Displays a dialog with copyright and licensing information.

FFD(Cyl) Space Warp

Create panel > Space Warps > Geometric/Deformable > Object Type rollout >
FFD(Cyl)

Create menu > Space Warps > Geometric/Deformable > FFD(Cyl)

Free-form deformations (FFDs) provide a method of deforming an object by
adjusting the control points of a lattice. The offset position of the control

Geometric/Deformable | 2767

points to the original lattice source volume causes the distortion of the affected
object.

The FFD(Cyl) space warp uses a cylindrical array of control points in its lattice.
This FFD is available as both an object modifier and a space warp. For
information on the object modifier version, see FFD (Box/Cylinder) Modifiers
on page 1460.

You create FFD space warps as separate objects similarly to the way you create
standard primitives: by dragging the mouse in the viewport. The result is a
lattice of control points. The source lattice of an FFD modifier is fitted to the
geometry it's assigned to in the stack. This might be a whole object or a
sub-object selection of faces or vertices.

Because FFD space warps are separate objects, they carry their own adjustable
dimension parameters among the creation parameters.

You can apply object modifiers to space warp objects. For example, you can
use the Linked XForm modifier with a space-warp FFD.

Procedures

Example: Create an animated tablecloth:

Finished tablecloth using FFD (Cyl) space warp

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This example shows how to use the FFD(Cyl) space warp to create a tablecloth
that flies in and drapes itself over a table.

Begin by creating the table and tablecloth.

1 Create a table from two cylinders. Make the table top with a radius of 30

units, and a height of 2 units. Make the "table stand" cylinder with a
radius of 3 and a height of 60.

2 Make a tablecloth from a box 100 units square and 0.5 units in height.

Increase Length and Width Segments to 30, and keep Height Segments
at 1.

3 Position the tablecloth so it's level with or slightly above the table top,

and a little less than 100 units to the left of the table edge, as seen from
the Top view.

4 Apply a nice wood grain to the table, and a checker to the tablecloth.

(Set the checker tiling to about 15x15, and choose any color for the
checkers.)

Now, set up a cylindrical FFD space warp that will form the drape of the
tablecloth over the table.

1 From the Create panel > Space Warps > Geometric/Deformable, choose

FFD(Cyl).

2 In the Top viewport, create a cylindrical FFD space warp, centered on the

table top, with a radius of 45 and a height of 5.

3 Click the Set Number of Points button and, in the Set FFD Dimensions

dialog, set Side points to 12, Radial points to 5, and Height points to 2.

4 Move the entire FFD lattice up until it's just over the surface of the table,

as seen from the Front viewport.

Geometric/Deformable | 2769

Next, adjust the control points of the lattice to drape over the table.

1 Zoom Extents All Selected.

2 On the Modify panel, in the stack display (below "Modifier List"), click

the FFD(cyl) item so it turns yellow. This means you've enabled direct
access to the FFD space warps control point sub-objects.

3 In the FFD Parameters rollout > Selection group, turn on All X. This lets

you select control points around the perimeter of the FFD cylinder.

4 In the Top viewport, use the Select and Move tool on page 959 and

region-select the two visible control points of the two outer rings of
control points at the nine-o'clock position. (This is easier shown than
described. You can actually region-select any number of vertices in the
two outer concentric rings of vertices. Because All X is on, all control
points for the two rings will be selected.)

5 On the status bar, click the Selection Lock Toggle button to lock

the selection. In the Front viewport, drag the selected points halfway
down the height of the table.

6 Unlock the selection, and then region-select any control point in the

outer ring to select all points in the outer ring.

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7 Lock the selection and, in the Front viewport, drag the outer ring of points

down to the floor.

You now have a truncated cone shape over the table.

8 Unlock the selection. In the Top viewport, again select all the control

points in the two outer rings.

9 Scale the selected control points in, until the radius of the inner ring of

points is slightly larger than the table top.

10 Select only the outer ring of points, and scale them so their radius is

slightly larger than the inner ring.

If necessary, move the points, as seen from the Front viewport, down to
touch the floor again.

You now have a lattice of control points draped over the table.

In this next series of steps, you'll bind the tablecloth to the FFD lattice, and
then animate it to move over the table.

1 In the stack display, click the FFD(cyl) entry again to exit the sub-object

level. It turns gray.

2 In the main toolbar, click the Bind to Space Warp button, and

drag between the FFD and the tablecloth.

Geometric/Deformable | 2771

3 Select the FFD lattice.

4 Choose Deform group > All Vertices.

The tablecloth is immediately deformed because all vertices are now
affected, including those outside the lattice volume, and Falloff is set to

0. A falloff value of 0 means that the distance of the vertices from the
lattice doesn't matter. Any number greater than 0, however, limits the
effect.

5 Set the Falloff spinner to 0.4.

No longer influenced by the FFD space warp, the tablecloth returns to
its square shape.

6 Turn on Auto Key, and go to frame 100.

7 In the Top viewport, select the tablecloth, and move it until it's centered

over the table.

8 As the tablecloth nears the table, it droops down to the floor, sweeps up

and over the table, and finally drapes itself over the table.

9 As you move the time slider back and forth and examine the animation,

you might find that the bottom of the tablecloth is deformed to the point
where it's hanging below the floor. To fix this, turn off Auto Key, go to
frame 100, select the lower ring of control points, and move them up

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until the tablecloth is at the height you want it. You can also adjust the
position of the other control points to create drapes, and so on.

10 On the Display command panel > Hide by Category rollout, turn on

Space Warps to hide the FFD space warp.

11 Set up appropriate lights and a camera, and play your animation.

Geometric/Deformable | 2773

Interface

2774 | Chapter 14 Space Warps and Particle Systems

This rollout lets you set the size and resolution of the lattice, and how it
displays and deforms.

Dimensions group

These options let you adjust the unit dimensions of the source volume, and
specify the number of control points in the lattice. Note that the point
dimensions are displayed beside the modifier name in the Stack list.

Radius, Height These two spinners display and let you adjust the length,
width, and height of the lattice. To create the space warp, drag the mouse in
the same way that you would to create a standard Cylinder primitive. Note
that these spinners don't exist in the object-modifier version of the FFD.

Label Displays the current number of controls points in the lattice (for
example: 4x8x4).

Set Number of Points Displays a dialog containing three spinners labeled
Side, Radial, and Height, plus OK/Cancel buttons. Specify the number of
control points you want in the lattice, and then click OK to make the change.

Side The number of control points around the perimeter of the lattice.

Radial The number of control points, radially, from the center to the outer

perimeter of the lattice.

Height The number of control points along the height of the lattice.

NOTE Make changes to the dimensions before you adjust the positions of the
lattice control points. When you change the number of control points with this
dialog, any adjustments you've already made to the control points are lost;
however, you can undo this use of the dialog.

Display group

These options affect the display of the FFD in viewports.

Lattice When on, lines are drawn connecting the control points to make a
grid. Although viewports can become cluttered when these extra lines are
drawn, they help to visualize the lattice.

Source Volume When on, the control points and lattice are displayed in their
unmodified state. This display is helpful when you're adjusting the source
volume to affect specific vertices that lie within or without it. See the All
Vertices and Only in Volume options, later in this topic.

Geometric/Deformable | 2775

Deform group

These options provide controls that specify which vertices are affected by the
FFD.

Only In Volume When on, only vertices that lie inside the source volume
are deformed. Vertices outside the source volume are not affected. This is the
default choice.

All Vertices When on, all vertices are deformed regardless of whether they
lie inside or outside the source volume, depending on the value in the Falloff
spinner. The deformation outside the volume is a continuous extrapolation
of the deformation inside the volume. Note that the deformation can be
extreme for points far away from the source lattice.

Falloff This spinner, enabled only when you choose All Vertices, determines
the distance from the lattice that the FFD effect will decrease to zero. When
this spinner is set to 0, it's effectively turned off, and there is no falloff; that
is, all vertices are affected regardless of their distance from the lattice. The
units of the Falloff parameter are specified relative to the size of the lattice: A
falloff of 1 means that the effect will go to 0 for points that are a lattice
width/length/height away from the lattice (depending on which side they are
on).

Tension/Continuity Lets you adjust the tension and continuity of the
deformation splines. Although you can't see the splines in an FFD, the lattice
and control points represent the structure that controls the splines. As you
adjust the control points, you alter the splines (which move through each
point). The splines, in turn, deform the geometry of the object. By altering
the tension and continuity of the splines, you alter their effect on the object.

Selection group

These options provide additional methods of selecting control points. You
can toggle any combination of the three buttons to select in one, two, or three
dimensions at once.

All X, All Y, All Z When one of these buttons is on and you select a control
point, all control points along the local dimension specified by the button
are selected as well. By turning on two buttons, you can select all control
points in two dimensions.

About Displays a dialog with copyright and licensing information.

2776 | Chapter 14 Space Warps and Particle Systems

Wave Space Warp

Create panel > Space Warps > Geometric/Deformable > Object Type rollout >
Wave

Create menu > Space Warps > Geometric/Deformable > Wave

The Wave space warp creates a linear wave through world space. It affects
geometry and behaves the same as the Wave modifier on page 2000. Use the
Wave space warp when you want the wave to affect a large number of objects,
or to affect an object relative to its position in world space.

Geometric/Deformable | 2777

Using a wave to deform a box

See also:

■ Ripple Space Warp on page 2781

Procedures

To create a Wave space warp:

1 On the Create panel, click Space Warps. Choose

Geometric/Deformable from the list, then on the Object Type rollout,
click Wave.

2 Drag in a viewport to define the initial size of the wave object icon.

The icon is displayed as a flat mesh wireframe.

3 Release the mouse button to set the icon size; then move the mouse to

define the initial amplitude of the wave.

4 Click to set the wave amplitude.

2778 | Chapter 14 Space Warps and Particle Systems

Interface

The initial amplitude sets both Amplitude 1 and Amplitude 2. Set these
parameters to unequal values to create a cross wave.

Wave group

These options control the wave effect.

Amplitude 1 Sets wave amplitude along the wave warp object's local X axis.

Amplitude 2 Sets wave amplitude along the wave warp object's local Y axis.

Amplitude is expressed in units. The wave is a sine wave along its Y axis and
parabolic along its X axis. Another way to think of the difference between the
amplitudes is that Amplitude 1 is at the center of the wave gizmo and
Amplitude 2 is at the edge of the gizmo.

Wave Length Sets the length of each wave along the wave's local Y axis, in
active units.

Geometric/Deformable | 2779

Phase Offsets the phase of the wave from its origin at the wave object's center.
Whole values have no effect; only fractional values do. Animating this
parameter makes the wave appear to travel through space.

Decay When set to 0.0, the wave has the same amplitude or amplitudes
throughout world space. Increasing the Decay value causes amplitude to
diminish as distance increases from the position of the wave warp object.
Default=0.0.

Display group

These options control the geometry of the Wave warp gizmo. In some cases,
such as when the two Amplitude values differ, they change the effect of the
wave.

Sides Sets the number of side segments along the wave object's local X
dimension.

Segments Sets the number of segments along the wave object's local Y
dimension.

Divisions Adjusts the size of the wave icon without altering the wave effect
as scaling would.

Flexibility parameter (Modify panel)

The Wave space warp also has a Flexibility parameter that you can adjust
individually in each bound object's stack, at the Wave Binding level. The
parameter belongs to each binding; it doesn't appear with the Wave warp
parameters.

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Flexibility Makes the bound object more or less responsive to the wave by
multiplying the amplitude by this value.

Ripple Space Warp

Create panel > Space Warps > Geometric/Deformable > Object Type rollout >
Ripple

Create menu > Space Warps > Geometric/Deformable > Ripple

Geometric/Deformable | 2781