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Particle Flow

Speed By Icon Operator

The Speed By Icon operator lets you use a special, non-rendering icon to control particle speed and direction.

When you add a Speed By Icon operator to the particle system in Particle View, the Speed By

Icon operator icon icon, or helper, appears in the scene at the world origin (0,0,0). When animated, the operator icon's motion is imparted to the particles. If you delete the icon, Particle

Flow also deletes the operator. To use the Speed By Icon operator:

1. Add a Speed By Icon operator to an event. Be sure to add it after any existing Speed

operators in the event. Alternatively, delete or turn off any existing Speed operators. The Speed By Icon operator icon appears at the world origin (0,0,0).

2. Animate the icon as you would any object. You can do this manually, or with a controller such as Path Constraint. See the following procedure for an example of this. The particles' motion is now under the influence of the animated icon.

3. Set the Speed By Icon parameters. With the icon selected, you can do this in the Modify panel. In general, the default Icon Animation Sync By setting, Event Duration, works

best. It causes the icon animation to be applied to the particles within the time frame of the event containing the Speed By Icon operator.

Example: To send particles along a path:

1. Reset 3ds Max, and then add a Particle Flow system in the Perspective viewport. 2. On the Create panel, click Shapes. Choose Splines, then on the Object Type rollout, click

Helix. In the Perspective viewport, at the center of the grid, create a helix shape. Then, on

the Parameters rollout, set the following: o Radius 1=100

o Radius 2=20 o Height=20 o Turns=3

o Bias=0 This will serve as the particle path.

3. Move and rotate the Particle Flow source icon so that it's at the start of the helical path, and aimed along the path, as shown. Get the base of the arrow as close as possible to the start of the path.

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1. Open Particle View (press 6).

2. In Event 01, click the Position Icon operator and set Location to Pivot. This causes the particles to be emitted in a thin stream.

3. Insert a Speed By Icon operator at the end of Event 01. The operator icon appears at the world origin.

4. Select the operator icon, and then, from the Animation menu, choose Position Controllers

Path Constraint. When you move the mouse cursor into the viewport, a rubber-band line joins the cursor to

the icon. 5. Click the Helix object.

The command panel switches to the Motion tab, and the controls indicate that 3ds Max

has applied a Position List controller to the icon, with the listed controllers being a Position XYZ and a Path Constraint. You can delete the former if you like, but it doesn't

make any difference for the purposes of this procedure. 6. Close Particle View, and then drag the time slider back and forth between its extents a

few times.

TipThe best way to view the results is from the Top viewport. The particles follow the path fairly closely, but diverge noticeably at the end of the path,

where the turns are tightest. Correcting divergence in tight turns typically requires an increase in the acceleration limit.

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1. Stop at frame 100. This will let you see the results of changing the Speed By Icon

parameters as you make the changes.

2. Go to the Modify panel. If necessary, select the Speed By Icon operator icon. The operator parameters appear on the Modify panel. This is the case with any action that uses a unique icon, and lets you adjust the parameters without using Particle View.

3. On the Parameters rollout, use the Accel Limit spinner to slowly increase the value as you observe the changes to the particle path. As you approach a value of 150, the end of the

particle path comes closer and closer to the Helix. You shouldn't see much change above 150.

1. Drag the time slider again.

The particle path remains similar to that of the Helix for the entire duration of the

animation. With other setups, you might need to use different values for Influence %, and for paths with tight twists and turns, you might need to increase Accel Limit as well. You might be wondering why you didn't simply replace the default Speed operator with

the Speed By Icon operator. To see why not, try this: 2. Go to frame 100, open Particle View, and click the Speed 01 operator's icon to turn it off.

Play the animation. The entire particle path is offset from the Helix, so it's difficult to tell how closely it follows the latter's curves.

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3. Try adjusting the Speed By Icon's Accel Limit and Influence % setting to get the particles to follow the helical path more closely.

It's not easy. You get more reliable results using the Speed operator to set the initial speed, and then Speed By Icon to set the particle path.

To use the Use Icon Orientation option:

The Use Icon Orientation option applies arc-like motion to the particles based on rotation animation of the icon. To best understand how it works, it's necessary to isolate its influence by

eliminating any potentially conflicting factors. 1. Reset 3ds Max, and then add a Particle Flow system in the Perspective viewport. Set its

position to the world origin: (0,0,0).

2. Open Particle View and click the Birth operator. Set Emit Stop=0. This causes all particles to appear at frame 0.

3. Click the Speed operator and press the Delete key to delete it. 4. Drag a Speed By Icon operator from the Depot to the end of Event 01.

The Speed By Icon operator icon appears at the world origin.

5. Select the Speed By Icon operator icon, and then right-click the icon and choose Rotate

from the menu. Go to frame 20, turn on (Auto Key), and rotate the icon 180 degrees

about the X axis.

6. Turn off (Auto Key). 7. Drag the time slider.

The particles aren't affected by the icon animation. Because the Speed By Icon operator icon is selected, the operator's parameters appear on

the Modify panel. 8. On the Modify panel, turn on Use Icon Orientation. Drag the time slider again.

This time, the particles move in unison with the icon rotation, as if they were glued to an

infinite plane coincident with the icon. 9. Go to frame 10, select the Particle Flow source icon (not the Speed By Icon operator

icon), and then right-click the icon and choose Move from the menu. Move the icon straight up, on the Z axis, about 100 units. As you drag upward, the particles move away from the icon.

10. Drag the time slider again. This time the particles move in an arc around the icon. 11. Try moving and rotating the two icons, playing the animation each time you make a

change. Also set Emit Stop back to 30. As you can see, the possibilities with just this simple setup are myriad. In combination with the many other variables and options in Particle Flow, they're endless.

The user interface appears in the parameters panel, on the right side of the Particle View dialog. When the icon is selected, the parameters also appear on the Modify panel.

Accel(eration) Limit The maximum amount, in system units per second per second, by which the particles' speed can change in order to match the speed of the operator icon. Default=100.0.

If the operator icon changes speed or direction rapidly, increase this value to let the particles follow it more closely.

TipUse a lower Accel Limit value for smooth motion, and a higher value when greater accuracy is needed, such as when the particles should hit a small target. You can animate this setting (use Sync By Event Duration) to specify different appropriate values,

depending on the required results. Influence %

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Determines the mix of the previous speed with the speed of the operator icon. Default=100.0. Range=0.0 to 100.0.

At the default value of 100, the speed is controlled only by that of the icon. At 0, the icon speed doesn't affect particle speed at all. At in-between values, the mix proportion is determined by the Influence % value.

Speed Variation Enables random variation of the particles' speed, so they don't all move at exactly the

same rate as the icon. Turn this on, and then set the minimum and maximum percentages of variation. Default=off. Using Speed Variation can help keep the particles from bunching up as they travel along

the animation path. Note, however, that each individual particle's speed doesn't vary; it travels at a constant speed.

Min %/Max % Set the minimum and maximum percentages, respectively, of particle speed variation. Default=50.0 (Min %), 100.0 (Max %).

For example, if you set Min % to 50 and Max % to 200, the particles will vary in speed between half and two times the speed of the icon.

Use Icon Orientation Applies animation of the icon's orientation to the particles. By default, Speed By Icon controls particle motion only by animation of the icon's

position. If you turn on Use Icon Orientation, Particle Flow also applies rotation of the icon to the particle motion. In essence, this motion is circular, and its extent depends on the distance between each particle and the icon. Default=off.

The best way to understand how this works is by using it. To try out Use Icon Orientation, see this procedure.

Steer Towards Trajectory Particles farther away than the Distance value from the icon are moved directly toward the icon. Default=off.

Distance Sets the distance between the particles and the operator icon beyond which Steer Towards

Trajectory takes effect. Default=10.0. Parameters Animation group If you animate the operator settings, Particle Flow can begin applying this animation to all

particles as of the start frame of the animation or the first frame of the current event, or to each particle based on its age. For instance, if you set Sync By to Particle Age, and set Speed

Variation keys at frames 0 and 30, then Particle Flow will animate the speed variation for each particle born while the event is active between its birth and its 30th frame of existence. Alternatively, if you set Sync By to Absolute Time, the speed variation is animated from frame 0

to frame 30 of the animation, even if no particles are in the event at that time. Or, if you set Sync By to Event Duration, the speed variation animation is applied to each particle as of the time that

it enters the event. For further information, see Animation Offset Keying group. Sync By

Choose the time frame for applying animated parameters:

Absolute TimeAny keys set for parameters are applied at the actual frames for which they're set.

Particle AgeAny keys set for parameters are applied at the corresponding frames of each particle's existence.

Event DurationAny keys set for parameters are applied to each particle relative to

the frame at which it first enters the event.

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Icon Animation group Particle Flow can begin applying animation of the Speed By Icon operator icon to all particles as

of the start frame of the animation or the first frame of the current event, or to each particle based on its age. Sync By

Choose the time frame for applying animation of the icon to the particles: Absolute TimeAny keys set for icon motion are applied at the actual frames for

which they're set. Particle AgeAny keys set for icon motion are applied at the corresponding frames

of each particle's existence.

Event DurationAny keys set for icon motion are applied to each particle relative to the frame at which it first enters the event.

Icon Size Sets the size of the operator icon. This setting is for visibility only; it doesn't affect particle behavior.

Uniqueness group The Uniqueness setting enables randomization of the speed variation range.

Seed Specifies a randomization value.

New

Calculates a new seed using a randomization formula. Particle Paint Helper

The Particle Paint helper enables you to apply particle seeds with a specific pattern and timing

onto the surface of one or more objects. Particle seeds painted with the Particle Paint helper are not particles, but are seeds that can be

turned into particles with the Birth Paint or Placement Paint operators in Particle Flow. You can spray particle seeds with a freehand painting tool, or by using 3ds Max splines to define the pattern. Particle Paint works in any orthogonal viewport such as a Front or Top view. It

sprays directly into the viewport (that is, perpendicular to the plane of view), and plants particle seeds on the surface of first object that it hits.

Particle Paint Icon

To create the Particle Paint icon, click Create panel Helpers Particle Flow Particle Paint, and

then drag in a viewport. The Particle Paint icon is composed of two parts: a circle and a spray can icon.

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The Particle Paint helper uses the metaphor of a real-world airbrush to spray-paint particle seeds onto a surface. When you use the Freehand paint tool, particle seeds are sprayed through a virtual

nozzle, as with an airbrush. The circle in the Particle Paint icon represents the size of the nozzle. If, on the other hand, you use stroke splines, the particle seeds are sprayed along the spline. The Particle Paint icon does not have to sit in front of or on the objects on which you plan to

paint particle seeds, nor does it have to be created in the viewport in which you plan to paint. Deleting the Particle Paint icon deletes all particle seeds and strokes associated with it.

Strokes The Particle Paint helper works with particle groupings called strokes. With a real-world airbrush, each time you depress the nozzle, spray, then release the nozzle, you create a stroke.

With the freehand tool, you can drag across objects several times to create strokes. With the spline method, you can pick several splines to create different strokes.

Each set of strokes stored with the Particle Paint helper can be used as a series of birth instructions with the Birth Paint and Placement Paint operators in Particle Flow. You can work with each stroke separately to adjust its timing, delete some of its particles, and perform other

operations. To edit particle seeds and strokes after creating them, select the Particle Paint helper and then access the Editing rollout on the Modify panel.

You can undo the creation of strokes, and you can also delete particle seeds or change particle seed timing with the options on the Editing rollout. You can also restart by deleting the Particle Paint helper and creating a new one.

Procedures Example: To create strokes with freehand painting:

1. Create a sphere in the Top viewport.

2. Click Create panel (Helpers). Choose Particle Flow, then on the Object Type rollout, click Particle Paint. Drag in any viewport to create the Particle Paint helper.

3. With the Particle Paint helper selected, go to the Modify panel. 4. On the Setup rollout, click Freehand Paint.

5. In the Front viewport, position the mouse cursor over the sphere. A set of nozzle crosshairs appear, indicating that Particle Paint is ready to paint. NoteYou can create freehand strokes only in orthographic viewports.

6. Drag the nozzle crosshairs over the sphere for a few seconds, then release. After you release, the particle seeds appear as +-shaped tick marks on the object surface.

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You have just created one stroke. 7. Move the time slider to a later frame.

8. Drag the nozzle over a different part of the sphere to create another stroke. 9. Click the Freehand Paint button to turn it off. 10. On the Editing rollout, turn on Show Particle Timing.

11. Drag the time slider to see the particle timing. As you drag the time slider, the particle seeds change color as they become eligible for

birth. You will see the second stroke begin at the frame to which you moved the time slider before making the stroke.

To create strokes with splines:

1. Create a 3D object in any viewport. 2. In the Front viewport, create two splines, such as a line and a circle. Place the splines so

they overlap the 3D object when viewed in the Front viewport. The splines don't have to actually be in front of the 3D object in 3D space. But because Particle Paint will project the splines onto the object to create particle seeds, the splines

must overlap the 3D object when viewed in the viewport. 3. Click Create panel Helpers. Choose Particle Flow, then on the Object Type rollout, click

Particle Paint. Create the Particle Paint helper in any viewport. 4. With the Particle Paint helper selected, go to the Modify panel. 5. On the Setup rollout, click Pick Stroke Spline.

6. Activate the Front viewport. 7. With the time slider at frame 0, click one of the splines in the Front viewport.

This creates the first stroke.

8. Move the time slider to a later frame, and click another spline. This creates a second stroke, starting at the current frame.

9. Click Pick Stroke Spline again to turn it off. 10. On the Editing rollout, turn on Show Particle Timing. 11. Drag the time slider to see the particle timing.

As you drag the time slider, the particle seeds change color as they become eligible for birth. You will see the second stroke begin at the frame to which you moved the time

slider before picking the second spline. The controls on the Setup, Orientation, and Mapping rollouts set parameters for particle seeds upon creation. These settings go into effect when you create the particle seeds with the freehand

or spline tool. Changing the parameter values after you create particle seeds has no effect on the seeds. After particle seed creation, you can change some aspects of seeds and strokes with the

Editing rollout settings. The Particle Paint rollouts are as follows: Setup Rollout (Particle Paint)

The parameters on the Setup rollout determine the density and placement of particle seeds as well as stroke timing.

ImportantFor these parameters to affect the strokes or seeds, you must set them before you create particle seeds. Changing values after creating particle seeds has no effect on the existing strokes or seeds.

Freehand Paint Activates a freehand paint tool, allowing you to drag anywhere in an orthographic

viewport to set particle seeds. The timing of the drag across an object determines the base timing for particle birth when used with the Birth Paint or Particle Paint operators. This option is available only on the Modify panel.

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ImportantTo use the freehand paint tool, you must work from one of the orthographic viewports such as Top or Front. You cannot use this tool in Perspective, Camera, or

Spotlight viewports. Each time you release the mouse while using this tool, you create an individual stroke. You can create as many strokes as you like for each Particle Paint helper. Particle timing

and other options for each stroke are governed by the other settings on the Setup rollout. To stop creating strokes, right-click in the active viewport or click the Freehand Paint

button again. Pick Stroke Spline

Allows you to pick one or more standard splines as paths for the particle seeds. Particles

are then placed along this spline, but are projected on to 3D surfaces into the orthogonal viewport. The splines do not have to be in front of the surfaces in the orthographic

viewport; Particle Paint will project from splines to surfaces as if the splines were in front of the objects regardless of their actual positions in 3D space. The picked splines can be either open or closed splines. NURBS curves cannot be used as

spray splines. You can pick as many splines as you like, and each spline picked is considered to be a

separate stroke. The stroke starts from the spline's first vertex, and continues along the spline until it reaches the end of the spline (or the first vertex, in the case of closed splines).

Total Particle Seeds The total number of particle seeds that have been generated.

Strokes

The number of strokes created by the Particle Paint helper. Brush Radius

Adjusts the spray emitter's nozzle size. The change in size is reflected in the Particle Paint icon. This value determines the distance around the center of the nozzle by which particle seeds spread when using either method to generate particle seeds. This value can be

animated over time. Paint Density group

These controls set the particle seeds' area of distribution within the emitter nozzle. Center (%)

Percentage of particle seeds that spray at the center of the nozzle.

Sides (%) Percentage of particle seeds that spray at the edges of the nozzle. Higher percentages

result in wider bands of particles. Paint Flow Rate group These controls determine how many particle seeds are emitted and how fast they are emitted over

the course of a single stroke. For the freehand paint method, a stroke is defined by the time you press the mouse button to start the stroke, until you release the mouse button. For a spline, one

stroke is distributed over each spline picked. Stroke Limit

Sets the overall number of particle seeds that can be emitted per stroke when using the

freehand or spline methods. So if Seeds p/sec is 25.0 and Stroke Limit is 100.0, you can spray for four seconds before running out of particle seeds with that one stroke. This

parameter is overridden by the Stroke spray rate type, selected under Type (see following).

Type

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Sets the spray rate type. The available choices are Time, Length, and Stroke. Each one works with one of the later parameters to set the spray rate.

TimeSets the spray rate by particle seeds per second. LengthSets the spray rate by spatial movement of the nozzle. StrokeSets the spray rate with a specific number of particle seeds per stroke,

regardless of stroke length. This option overrides the Stroke Limit parameter (see preceding).

[rate value] Depending on the Type setting (see preceding), one of these is available to set the number of seeds created when painting.

Seeds p/secThe number of particle seeds emitted per second as you draw in viewports. Higher values cause more seeds to be emitted. This option is available

only for the Time spray rate type (see preceding). Paint StepThe distance the nozzle center must move between emitting individual

particle seeds. Higher values cause fewer seeds to be emitted during a stroke. This

option is available only for the Length spray rate type. Total AmountDetermines the total number of particle seeds per stroke, regardless

of the stroke length in units or time. Seeds are evenly distributed over the stroke time. This option is available only for the Stroke spray rate type.

Brush Adjustment group

These controls are used for fine-tuning the Brush Radius and Flow Rate with regard to stroke timing. Radius

Provides for varying the seed-painting radius over the course of each stroke. Alternatively, you can animate the Brush Radius parameter to vary the brush size, but that

animation occurs in absolute time (that is, within a specific frame range). Use this option to adjust the brush radius within a single stroke regardless of its start and end times. Clicking Radius opens the Brush Radius Graph (Particle Paint). The settings on the graph

are in effect when the Radius option is on. Rate

Provides for varying the seed-painting rate over the course of each stroke. Alternatively, you can animate the Seeds p/sec parameter to vary the rate, but this animates the rate in absolute time (that is, within a specific frame range). Use the Rate option to adjust the

seed painting rate within a single stroke regardless of its start and end times. Clicking Rate displays the Paint Flow Rate Graph (Particle Paint). The settings on the

graph are in effect when the Rate option is on. Display Type

This drop-down list gives you the choice of how to display the particles in the viewports.

You can choose Ticks or Flags as the display type. The Flags type gives more information about each seed’s rotational data. The pole of a flag marker is aligned with its seed’s local

Z axis, while the banner points in the direction of the local X axis. Particle Size

Sets the size of the flag markers. Available for the Flags type only.

Stroke Start group The settings in this group determine the start frame for particle seeds generated by a stroke. These

timing values can be used later by the Birth Paint and Placement Paint operators for precise timing of every particle emitted. Stroke Start

Choose either of the following:

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Current FrameStarts the stroke timing at the current frame. FixedStarts the stroke timing at the indicated frame.

Stroke Stop group These settings specify the method for determining the duration or stop frame of the stroke. Stroke Stop

Choose one of the following: Real-Time OffsetDefines stroke time by the actual time taken for drawing the

stroke. If you created a stroke by picking a spline, then the default time for the stroke is one second. Use the Time Scale % parameter to define the correspondence between the

animation time (frames of animation) and the real-world time when a stroke is drawn. For example, a value of 100.0 means that one second of actual time

corresponds to 30 frames of animation (for NTSC), while a value of 50.0 means that one second of stroke drawing corresponds to 15 frames of animation. NoteAdjusting the Time Scale % value changes the effective flow rate of the

painting, since the Seeds p/sec parameter uses animation time, not drawing time. FixedStops the stroke at the specified frame, in absolute time.

DurationSets the stroke length in frames. Auto Adjust Current Frame

Aligns the start of each successive stroke automatically with the stop time of the previous

one. If you turn on this option for an exsisting stroke, the time slider is adjusted to the stop moment of the stroke. This option is available only if Stroke Start is set to Current Frame and Stroke Stop is set to either Real-Time Offset or Duration.

Auto Adjust Global Timing Adjusts emission timing of the related Birth Paint operator automatically.

The Birth Paint operator has its own parameters that define when particles start and stop emission. When this switch is off, Particle Flow fits the timing of the strokes into the Birth Paint operator’s Start/Stop interval. However, when this option is on, Particle Paint

allows the related Birth Paint operator to adjust its emission timing to the timing of the strokes.

Icon Size Adjusts the overall size of the helper icon, but does not affect the nozzle radius.

Paint Spread Uniqueness group

These settings randomize particle-seed distribution over a stroke. If you pick the same spline for a stroke, the helper generates the same placement for seeds. To generate varied particle

placement for the same spline, change the Seed value. Seed

Specifies a randomization value. Not otherwise related to particle seeds.

New Generates a new Seed value.

Layout Rollout (Particle Paint) The settings on this rollout determine how the particles are placed on objects in the scene. The Layout settings affect all particle seeds associated with the Particle Paint helper, either before or

after they are created. Interface

[paint option]

Choose a painting option:

Paint on All ObjectsAllows particle painting on any object in your scene.

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Paint on Objects ListedAllows particle painting only on listed objects. Click Add to pick objects from viewports, or By List to choose from a dialog. The names of

paintable objects appear in the list. To delete an object from the list, highlight it and then click Remove.

Animated Objects

If the object on which particle seeds are placed is animated, the original stroke placement might not be at the same place as the animated surface at the time particles are born. If

you want particles painted on animated objects to be born from the animated surface regardless of the surface's position, orientation, or shape by the time the particles are born, turn on this option.

The Particle Paint helper works with any animated object, whether animated by transforms or another method, such as sub-object animation, morphing, or skinning

operations. If the surface animation involves a change in the number of faces (as with the Optimize modifier), Particle Paint might fail because the seeds are linked to specific faces by face indices.

Include Children Allows painting on linked children of listed objects.

Include Group Members For groups in the list, allows painting on all group members.

Use Mask Objects

Lets you use a mesh or patch object as a mask or frisket to block particles from being sprayed in that area. Click Add to pick objects from viewports, or By List to choose from a dialog. The names of selected objects appear in the list. To delete an object from the list,

highlight it and then click Remove. NoteMask objects block painting only where their geometry is above (or closer to the

viewpoint than) the painted surface in the viewport in which the painting occurs. Also, mask objects cannot receive particle seeds.

Include Children

Linked children of listed objects also mask the painting. Include Group Members

For groups in the list, all group members mask the painting. Selection Filter

Restricts painting to selected areas of geometry. Choose one of the following:

NoneNo restriction. Selected Faces OnlyPaints particle seeds only at the geometry's selected faces.

Soft SelectionUses Soft Selection on a selection of the geometry's vertices or faces. Fewer particle seeds will be placed areas where the selection falls off.

Particle Location group

These controls determine how to distribute particle seeds on the geometry. Particle Location

This drop-down list lets you choose where particle seeds will be deposited. The choices are:

At SurfaceParticle seeds will reside on the surface of any objects on which they

are painted. Above SurfaceParticle seeds will be placed above the surface of objects on which

they are painted. Set the distance above the surface with the Distance parameter. Below SurfaceParticle seeds will be placed below the surface of any objects on

which they are painted. Set the distance below the surface with the Distance

parameter.

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Above And Below SurfaceParticle seeds will be placed both above and below the surface of any objects on which they are painted. Set the distance from the surface

with the Distance parameter. Distance

The distance above or below the surface that particles seeds are placed. This value is

expressed in units. Variation

Adds variation to the distance from the surface that particle seeds are placed. Separation

When on, Particle Paint attempts to keep particle seeds apart by the specified distance,

expressed in 3ds Max units. Max Attempts

When Separation is on, Particle Paint attempts to separate particles by generating seeds repetitively until the desired separation is achieved. The Max Attempts parameter sets the number of times Particle Paint will generate seeds to attempt separation. If the Distance

value is low and Separation is high, the desired separation might not be achieved even after many attempts. In this case, turn on Stack Up For Separation (see following).

Stack Up For Separation When on, instead of using repetitive seed generation to attempt to separate particles, the separation conflict is resolved by moving the conflicting seed away in the direction of the

surface normal. Orientation Rollout (Particle Paint) The Orientation rollout controls the way particle seeds are oriented on surfaces. The orientation

information can be used by the Birth Paint and Placement Paint operators to rotate particles in space. These options are useful when you plan to use instanced shapes with a visible orientation

as particles. ImportantTo have these settings affect the particle seeds, set these parameters before you create the seeds. Changing these parameter values after creating particle seeds has no effect on the

existing seeds' orientation. Interface

Generate Rotational Comp. Enables control over the orientation of particle seeds. The remaining settings on this rollout are available only when this check box is on.

X-Axis and Z-Axis groups Priority Axis

Sets the axis as the primary axis. When the X axis is chosen as the Priority Axis, each particle first aligned by its local X axis in the manner specified in the drop-down list, and then the local Z axis is used. If the Z axis is chosen as the Priority Axis, each particle is

aligned first by its local Z axis, and then its X axis. Reverse

Reverses the direction of the Priority Axis. This has the effect of rotating particles by 180 degrees so they point in the opposite direction.

[orientation list]

Use this drop-down list to specify how Particle Flow orients particles with respect to the surface of the painted object.

RandomOrients the particles on the surface at random, according to the chosen axis.

Align to Surface NormalAligns particles to the surface normal of the object upon

which they were painted. For example, if X is selected as the Priority Axis, the

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local X-axis for a particle is aligned with the surface normal. This option is suitable for placing instanced grass or hair objects on a surface.

Align to World X/Y/Z-AxisAligns the particles along the respective world axis. Look at ViewportForces all particles to align with the active viewport. Look at Particle Paint IconForces all particles to face the Particle Paint Icon.

Follow StrokeAligns particles along the spray path in the direction in which the stroke was drawn.

Align to U/V/W Map VectorAligns particles along the U/V/W mapping direction on the surface of the painted object.

Divergence

Sets the maximum degree of variation off the chosen Priority Axis, expressed in degrees. Mapping Rollout (Particle Paint)

The Mapping rollout determines how particles are mapped. To use mapping with particle seeds, add a Material operator to the event, and assign a material that has mapping. ImportantTo have these settings affect the particle seeds, set these parameters before you create

the seeds. Changing the parameter values after creating particle seeds has no effect on existing seeds' mapping.

Interface Acquire Sub-Material Index

Causes each particle seed to acquire the sub-material index (Material ID) of the nearest

point of the surface painted. Generate Mapping Coords.

Creates mapping coordinates for each particle seed according to the Type selection. If you

use this option, do not use a Mapping operator with the Birth Paint or Placement Paint operator, because doing so will override the mapping generated by the Particle Paint

helper. Assign To Mapping Channels

Defines the mapping channels to which mapping values are assigned. You can choose

more than one channel for assignment. Available only when Generate Mapping Coords. is on.

Type Lets you specify how Particle Paint assigns mapping to particles. These mapping types work with numeric parameters to set mapping on particle seeds. For example, with a

planar map the bottom-left corner has UVW values of 0,0,0, while the top-right corner has UVW values of 1,1,0. These mapping types correlate these values to the stroke.

Stroke DependentSpreads mapping values from the Start Value to the End Value over the course of the stroke. The first particle in the stroke receives the Start Value, the last particle of the stroke receives the End Value, and intervening particles receive values interpolated between the two.

The same value is assigned to U, V, and W. Time DependentAssigns mapping values according to time. The first particle in the stroke is

given the Start Value, and the timing of each successive particle (in relation to the first particle) receives an incremented value according to the Offset p/Sec parameter and the number of seconds elapsed. For example, if Offset p/Sec is 0.25 (the default value), then a four-second

stroke covers the 0-1 range of UV mapping values. Index DependentAssigns mapping values incrementally regardless of the stroke time. The first

particle in the stroke is given the Start Value, and each successive mapping value increments by the Offset p/Particle value. For example, if Offset p/Particle is 0.01 (the default value) and a stroke has 101 particles, then particles in the stroke receive the incremental mapping values 0.0,

0.01, 0.02, 0.03, ... 0.98, 0.99, 1.0.

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From Object PaintedParticle seeds take their mapping from their placement on the painted object. A particle acquires the mapping values at the nearest point of the object surface. To acquire

mapping values from several mapping channels of the object, activate multiple buttons in the Assign To Mapping Channels group. Editing Rollout (Particle Paint)

The Editing rollout lets you delete unwanted particle seeds or whole strokes, adjust stroke/particle timing, and select particles/strokes and pass the selection data to the Birth Paint

and Placement Paint operators. You cannot directly manipulate selected particle seeds with standard 3ds Max tools such as Move and Rotate. This rollout appears only on the Modify panel.

Two levels of sub-objects are available for selection: Particles and Strokes. The As with other sub-object types in 3ds Max, each level remembers its selection. Selected particles are red.

Particle Lets you select particle seeds by clicking them or dragging a region.

Event

Lets you select entire strokes. At this level, you can select all particle seeds in one or more strokes with standard selection methods.

Show Particle Timing When on you can scrub the time slider to see particle timing in the viewports. Particles start out with the color specified by the Show Particle Timing color swatch. As you scrub

the time slider, each particle turns white when it reaches its emission time. The particle timing displayed with this option is taken from the current stroke timing settings stored in the Particle Paint helper. This timing might differ from the timing set by

a Birth Paint operator. Available only when not at a sub-object level (Particles or Strokes).

Delete Selected Items Deletes selected particles or strokes. You can also use the Delete key.

Combine Into Single Stroke

Combines selected strokes into a single stroke. The particle seeds are intermixed according to their relative timing. You can use this tool to combine short or single-particle

strokes into a larger stroke. Available only at the Stroke sub-object level when multiple strokes are selected.

Equalize Particle Timing

Evens out the distribution of particle timing within a stroke. This tool is useful for evening out strokes where some particles have been deleted.

Available only at the Stroke sub-object level. Auto Sync Timing by Sel.

When on, sets Start At, Stop At, and Duration (see following) to the current start frame,

stop frame, and duration of the currently selected stroke. This option takes effect only if a single stroke is selected.

Current Start Shows the start frame of the currently selected stroke(s). If multiple strokes with different start times are selected, then the value shown is <multiple>.

Start At The start time for selected strokes. If you change this value, the new time goes into effect

when you click Adjust Stroke Timing. Current Stop

Shows the end frame of the currently selected stroke(s). If multiple strokes with different

end times are selected, then the value shown is <multiple>.

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Stop At The end time for selected strokes. If you change this value, the new time goes into effect

when you click Adjust Stroke Timing. You can choose either this method or the Duration method for changing the length of the stroke.

Cur. Duration

Shows the duration of the currently selected stroke(s). If multip le strokes with different durations are selected, then the value shown is <multiple>.

Duration The duration of selected strokes. A change to this value goes into effect when you click Adjust Stroke Timing. You can choose either this method or the Stop At method for

changing the length of the stroke. Auto-Adjust Global Timing

When on, changing the stroke timing automatically changes the timing in any related Birth Paint operators in Particle Flow. This option has an effect only if a Birth Paint operator that references the Particle Paint helper is present in the scene.

Adjust Stroke Timing Adjusts the timing of selected strokes to match the values for Start At, and Stop At or

Duration. Total Particles

Displays the total number of particle seeds associated with the Particle Paint helper.

Total Strokes Shows the total number of strokes in the Particle Paint helper.

Selected Particles

Shows the number of selected particles. At the Particles sub-object level, it shows the number of selected particles. At the Strokes sub-object level, it show the total number of

particles in the selected strokes. At the object level, it displays the number of selected particles at the Particles sub-object level.

Selected Strokes

Shows the number of selected strokes. The value changes for different sub-object levels. At the Particles level it shows the number of strokes that have selected particles. At the

Strokes level it shows the number of directly selected strokes. At the Object level it shows the same amount as in the Strokes level.

Selected Stroke #

Shows the sequence number of the currently selected stroke. Strokes are stored in the order in which they are made.

Initial State Operator

The Initial State operator is a birth operator that uses a snapshot of another particle system or other events as a starting point for a new event. The particle system or events from which the

Initial State operator gets its snapshot must be different from those of the Initial State operator itself.

The Initial State operator can make use of an icon in the scene, whose default size is 0.0. The icon is visible only if the Icon Size parameter is greater than 0. You can also use the Initial State helper object (in the Particle Flow category) to create an Initial

State icon and a corresponding Initial State event at the same time. NoteTo avoid looping dependencies, create the Initial State operator after you create the particle

system or events from which it obtains its initial state. Initial State Usage The Initial State operator is particularly useful when a large number of particles are generated

before frame 0, and you want to use the state of particles at frame 0.

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In the following example, the left side of the image shows the original wiring without the Initial State operator. Because 1,000,000 particles are born starting at frame -750, a great deal of

calculation is required to calculate the particles at frame 0. In a particle system like this, you can save time by using the Initial State operator. In this case, you could set the Viewport Quantity Multiplier in the original system to 100%, and then let the

system calculate the particles at frame 0, which could take 15 minutes or more. Then you would use the Calculate Initial State function in the Initial State operator to acquire the starting state of

particles at frame 0. The first time you perform this operation, it will take as long as particle calculation without the Initial State operator. The advantage is that the initial particle state at frame 0 does not have to be calculated again unless you change parameters that affect the initial

state. The original system generates particles from frame -750 to 144, but the Initial State operator

captures the state at frame 0. Therefore, you would need an additional Birth operator to generate particles from frames 0 to 144. To determine how many particles to generate from frames 0 to 144, look at the Initial State operator to get the number of particles generated, and subtract this

number from the original total; the result is the number of particles should be generated with the new Birth operator. In the example shown above, the amount is 1,000,000–834,000 = 166,000.

If the original particle system has Position and Speed operators, be sure to instance them in the new event with the Birth operator. There is no need to instance these operators in the event that contains the Initial State operator, as this information is already included in the referenced event.

All other operators can go into a common event where the Birth and Initial State events merge. To use Initial State:

1. Create a particle system.

2. Go to the frame where the particle system is in the desired initial state. 3. Drag the Initial State operator to a blank area of Particle View to create a new, separate

event. Alternatively, you can use the Initial State helper to create an Initial State icon and a new event at the same time.

4. Decide if you want the whole particle system, or distinctive events for the initial state, and

choose the appropriate option in the Initial State From group. 5. Select the particle system or events.

6. Click Calculate Initial State. The Initial State UI makes a snapshot at the current frame, and also reports the number of the particles in the initial state and the amount of memory used.

7. At this point, you can disable the original particle system if you like. 8. Drag an Empty Flow to a blank area of Particle View to create a new global event.

9. Wire the new global event to the event that includes the Initial State operator. Interface Calculate Initial State

Creates a snapshot of a particle system or selected events at the current frame. The snapshot uses only particles visible in the viewport, and is reflected by the Amount and

the Memory Used statistics. This button becomes available after you specify a particle system or events. Initial State uses the Viewport % and Render % in the PF Source's Quantity Multiplier

group. If Viewport % is set to 100, all particles in the snapshot are used. If Viewport % is less than 100, then only some particles of the original initial state are used. If Viewport %

is greater than 100, the operator spawns particles from the original state to meet the percentage. The Initial State operator moves the particles apart in order to separate the spawns visually, and can modify the speed of the spawns.

Emit Time

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All particles in the initial state are generated at the Emit Time. Auto Sync Emit Time

Sets the Emit Time value to the current frame automatically when you click Calculate Initial State button. This action synchronizes the referenced particle system's timing with the operator.

Amount Read-only field shows the number of particles in the initial state, which is the number of

visible particles in the original particle system during the snapshot. Keep in mind that the operator grabs the viewport state of a particle system. What you have in the viewport at the snapshot frame is what you get for the initial state.

Memory Used Read-only field shows the amount of system memory used to keep the initial-state data

when the scene is saved into a file, in kilobytes. Initial State From

Choose a source option for the initial state and then make settings as appropriate.

Particle SystemLets you derive the initial state from an entire particle system. Click the button to choose the particle system. You cannot use the particle system

that contains the Initial State operator. Selected EventsLets you choose any number of events to use for the initial state.

To add events to the list, click Add. You cannot add the event the Initial State

operator is in. To remove an event from the list, highlight the event and click Remove.

Initial State Data group

The options in this group serve two purposes: Before you click Calculate Initial State, the settings define the types of data to get from

the particle system or events for the initial state. After you click Calculate Initial State, the settings define the data to be used during

particle generation.

When you click Calculate Initial State, the operator reads the status of the check boxes in this group and acquires the indicated data from the particle system or events. If a check box is on and

the data corresponding to that checkbox is available from the particle system or events, the checkbox text is black. Otherwise, it is gray. You can toggle a check box whether its text is black or gray.

If the data is available (the checkbox text is black) and you turn off the check box, the data is not used when particles are generated.

Age When off, all particles are born with age 0. When on, each particle retains its age as of the moment of the snapshot.

Speed/Scale/Rotation/Spin/Shape When on, these options derive the corresponding type of data from the snapshot.

Mapping Takes data from a Mapping operator. To make this option work properly, turn on Show Map in Viewport for the original Mapping operator.

Material ID Takes the sub-material index assignment, To make this option work properly, turn on

Assign Material ID and Show in Viewport for all Material operators. Script Data

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Takes the Script Float, Integer, Vector and Matrix data created by Script operators. This data can be used later by Script operators as well as by the Script Vector option of the

Find Target test Point setting. Selection

Takes particle selection data. Any selections in the Initial State operator’s particle system

is overwritten by the snapshot selection. For Quantity Multiplier > 100% group

The options in this group have an effect on particles only if the Viewport % (or Render %) in the PF Source's Quantity Multiplier group is greater than 100%. To meet the requirement of the Quantity Multiplier, the operator has to spawn the acquired particles.

Position Variation Max. Spread The maximum offset of spawned particles’ placement from the original location.

Speed Variation Magnitude % Variation in the speed magnitude for spawned particles. The variation is defined as the maximum percentage change from the original speed. For example, if the original speed is

100 units per second and Magnitude is 20%, then the spawned particle may have any speed from 80 to 120.

Speed Variation Divergence Directional variation of the speed for the spawned particles, in degrees, with a range from 0 to 180.

Lock To Icon TM group The options in this group are used to link initial particle placement and speed to the operators 3D icon.

Position When on, you can modify the particles’ initial placement by moving, rotating, and scaling

the operator icon. Speed

Causes the particles’ initial speed after the snapshot to be affected by transform animation

of the operators icon. Icon Size

Sets the icon size. If you create the operator in Particle View, the default size is 0, and the icon is not visible in viewport. If you create the operator as a Particle Flow helper object, then the size is set when you drag in a viewport during the icon-creation process.

Color Coordinated When this option is turned on, the color of the 3D icon is synchronized with the color of

the Display operator in the same event. When this option is off, the icon has a standard Particle Flow operators color (blue).

Uniqueness Group of Controls

The Uniqueness setting enables changing the randomization of the position and speed variation when Quantity Multiplier is greater than 100% (see the For Quantity Multiplier 100% group).

Seed Specifies a randomization value.

New

Calculates a new seed using a randomization formula. Find Target Test

By default, Find Target sends particles to a specified target or targets. Upon reaching a target, the particles become eligible for redirection to another event. You can specify that the particles should use a particular speed or time frame in moving toward the target. You can also specify

where on the target the particles should go.

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Alternatively, you can use Find Target as a simple proximity test: If a particle comes within a certain distance of its target, it becomes eligible for redirection to the next event.

When you add a Find Target test to the particle system in Particle View, a spherical Find Target icon, or helper, appears in the scene at the world origin (0,0,0). You can use this icon as a target, or you can use one or more mesh objects in the scene as targets. To display the Find Target

parameters on the Modify panel, select the icon. If you delete the icon, Particle Flow also deletes the test.

Note: If you add Find Target from the Create panel, Particle Flow creates a separate event for the test in the particle diagram. Tip: In a particle loop, all particles end up at their respective starting positions, enabling seamless

repetition of the resulting animation. You can make particle loops with Particle Flow using a Script operator and a Find Target operator. At the start of the loop, the Script operator should

read all particle positions and write them into the MXS Vector channel. Then, at the end of the loop, set the Find Target operator to Control by Time, set Timing to Absolute Time, set Time to the end of the loop, and in the Target group, set Point to By Script Vector. Particle Flow will

direct particles to the previously cached position at the specified frame. The user interface appears in the parameters panel, on the right side of the Particle View dialog.

Control By ... The drop-down list at the top of the parameters panel lets you choose whether to send particles to a target by specifying the speed and acceleration, or by specifying the amount

of time they should take. Alternatively, by choosing No Control, you can test particles' distance from a target.

Control By SpeedSpecify speed and acceleration settings for the particles to

follow while traveling to the target. Use the Control By Speed group to set the parameters.

Control By TimeSpecify time-based settings for the particles to follow while traveling to the target. Use the Control By Time group to set the parameters.

No ControlWith this option, Find Target functions only as a proximity test. When

a particle comes within the specified distance of the target, the particles become eligible for redirection to the next event.

NoteWhen you choose No Control, the Find Target test does not affect particle speed or direction.

Test True If Distance To group

These settings let you choose which distance the Find Target test measures and specify the measured distance. You can choose Target Pivot or Target Point, and specify a distance with the

Is Less Than setting. Target Pivot

Measures the distance between the particle and the target pivot.

If the particles are directed to the outside of the target and the Is Less Than value is small, this condition might never be satisfied.

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Target Point Measures the distance between the particle and the target point.

Is Less Than When particles are closer than this distance from target pivot or point, they test True and become eligible for redirection to the next event. Measured in scene units.

NoteIf you set Is Less Than to 0, the particles might never test True. This might be desirable for an animation of, for example, bees buzzing around a flower but not landing

on it. In this case, you might want to use a low value for Accel Limit so the bees don’t circle too close to the flower.

Control By Speed group

Use these settings to specify speed and acceleration parameters when using Control By Speed or Speed Then Time. This group is available only when using Control By Speed.

Use Cruise Speed When on, Particle Flow gives you explicit control over particle speed and speed variation. When off, Particle Flow calculates particle speed automatically using the Accel Limit

value. Default=on. Speed

Particle speed in scene units per second. Default=300.0. Variation

The amount by which the actual Speed value can vary randomly. Default=0.0.

To obtain the actual speed for each particle, the system multiplies the Variation value by a random number between –1.0 and 1.0, and then applies the result as a percentage of the Speed setting. For example, if Speed=200 and Variation=10, then the actual speed for

each particle would vary randomly between 190 and 210. Accel Limit

Sets the acceleration limit. This value impacts the inertia and speed of the particles. Default=1000.0. The default acceleration limit value is based on the default Speed value of 300.0. If you

change the Speed value, it is recommended that you also change the Accel Limit value proportionately.

TipUse a lower Accel Limit value for smooth motion, and a higher value when greater accuracy is needed, such as when the particles should hit a small target. You can animate

this setting (use Sync By Event Duration) to specify different appropriate values,

depending on the required results. Ease In %

Controls the rate by which particles slow down when it approaches the target point. Particle Flow calculates the final speed with this formula: (100% – Ease In) * Speed.

Therefore, if the Ease In value is 100%, a particle should approach the target with a speed of 0, and if Ease In is 0%, the particle doesn't slow down at all when approaching the target. At intermediate values, the speed is calculated according to the distance to the

target point, as linear interpolation between the initial (cruise) speed, and the final speed. When a particle enters the event, the distance to the target point is calculated and later

used for the interpolation. Default=0.0. Sync By

Choose the time frame to use when animating Speed, Variation, and Accel Limit:

Absolute TimeAny keys set for parameters are applied at the actual frames for which they're set.

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Particle AgeAny keys set for parameters are applied at the corresponding frames of each particle's existence.

Event DurationAny keys set for parameters are applied to each particle starting when it first enters the event.

Control By Time group

Lets you specify the amount of time particles should take to reach the target. This group is unavailable when using Control By Speed.

Timing Determines how Particle Flow applies the specified timing, defined by the Time and Variation values. The possible options are:

Absolute TimeTime refers to the overall time of the system. Each particle will reach its target at the frame number specified by Time.

Particle AgeTime refers to the time elapsed since the birth of the particle. Each particle will reach its target when its age reaches the value specified by Time.

Event DurationTime refers to the time elapsed since the particle entered the

current event. Each particle will reach its target when it has been in the current for the number of frames specified by Time.

Time The number of frames particles should take to reach the target. Default=60.

Variation

The number of frames by which Time can vary randomly. Default=5. To obtain the actual time to the target for each spawned particle, the system multiplies the Variation value by a random number between –1.0 and 1.0, and then adds the result to the

Time value. For example, if Time=60 and Variation=20, then the time to target for each particle would be between 40 and 80 frames.

Subframe Sampling Turning this on helps avoid particle "puffing" by timing particles at a much higher subframe resolution (that is, throughout each frame), rather than using the relatively

coarse frame resolution. Default=on. "Puffing" is the effect of clustering particles, rather than producing a continuous stream.

This effect is especially noticeable when the emitter is animated. Use Docking Speed

Lets you specify particles' speed when they reach the target.

A particle might be required to reach the target from a specific direction at a specific speed. When Use Docking Speed is off, Particle Flow calculates a path for particles to

reach the target in the shortest distance with the least acceleration along the path. When Use Docking Speed is on, Particle Flow calculates particles' final speed when they reach the target using the Speed and Variation parameters. Therefore if you want a “smooth

landing,” set Speed to 0.0. Default=off. Speed

The speed of particles when they reach the target in scene units per second. Default=100.0.

Variation

The amount by which the actual Speed value can vary randomly. Default=0.0. Target group

By default, Find Target uses its own target icon, but you can use these controls to designate other scene objects as targets instead. Icon

Use the Find Target icon as the target.

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Each Find Target test has its own target icon. Even if you don't use it as a target, it still influences particle behavior if you set the docking type to Parallel, Spherical, or

Cylindrical. Mesh Objects

Use one or more scene mesh objects as targets. Choose this to make the list and list-

management buttons available. If you designate more than one target, the target used by each particle is determined by

the choice in the Object drop-down list in this group. [list]

Shows the mesh objects used as targets. If more than three target objects apply, a scroll

bar appears at the right side of the list. Add

Click this button, and then select a mesh object in the scene to add it to the list as a target. By List

Click this button, and then use the Select Target Objects dialog to add one or more mesh

objects to the list. The objects must already exist in the scene, and the dialog shows only eligible objects.

Remove To remove a target object from the list, first highlight it and then click this button. Any removed objects remain in the scene.

Sync By Choose the time frame to use when sending particles toward animated objects when using Animated Shape or Follow Target Animation:

Absolute TimeAnimation derived from the target is applied to particles immediately.

Particle AgeAnimation derived from the target is applied to particles at the corresponding frames of each particle's existence.

Event DurationAnimation derived from the target is applied to particles is applied

to each particle starting when it first enters the event. Animated Shape

Turn on to allow particles to target the surface of an object whose form is animated by scaling, by morphing, or with modifiers. This requires more computation, because the destination must be updated at every integration step.

Follow Target Animation Turn on to allow particles to follow a moving target; that is, a target whose location is

animated. This requires more computation, because the destination must be updated at every integration step.

Point

Lets you specify where on its target a particle should land. RandomEach particle targets a random point on the target.

Closest SurfaceEach particle targets the nearest point of the target’s surface. By Script VectorThe target point or points are defined using a Script operator that

defines values in the particleVector channel. The Script operator can be anywhere

upstream of the Find Target test. NoteWhen using By Script Vector to target absolute positions, such as vertex

locations, be sure to set Target to Icon. If you set it to Mesh, the positions specified by the script will be relative to the position of the mesh object. This latter option is useful for placing scripted targets on the surface of a moving

object.

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Object With multiple mesh targets, lets you specify how Particle Flow should choose among

them. Available only when targeting more than one object. RandomFor each particle, Particle Flow chooses a target object at random. Closest PivotFor each particle, Particle Flow chooses as its target the object whose

pivot is nearest to the particle. Closest SurfaceFor each particle, Particle Flow chooses as its target the object

whose surface is nearest to the particle. Least DeviationFor each particle, Particle Flow chooses as its target the object that

requires the least change in its current direction (or resteering) to reach.

By Script IntegerFor each particle, the choice of a targeted object is defined by a script operator that sets an index. This index corresponds to a target-object entry

position in the target list. See Script Operator Example. Lock On Target Object

When on, Particle Flow calculates each particle's target object once: when the particle

enters the event. Thereafter, the particle is “locked on” to its target object. When off, Particle Flow can continually recalculate the target object for each particle. Available only

when multiple target objects are designated. For example, if you set particles to target the closest surface, due to the target animation and particle movement, the definition of the closest surface is constantly changing. Thus

the particle may change the target object due to the circumstances. NoteEach time Find Target sets a target object, it “locks on” to a specific point on that object. This point can change only if the target object changes. Thus, with a single target

object, the target point always remains constant relative to the target object. That is, if the target object or its surface is animated, and Follow Target Animation or Animated Shape

is on, the absolute coordinates of the target point may change. NoteWhen Lock On Target Object is off, more calculation is required because the system might have to recalculate each particle's optimal target point in each frame.

Docking Direction group Docking type

Lets you specify from which direction particles should approach targets. None SpecifiedNo docking constraints. Particles reach their targets in the most

efficient way, based on their assigned parameters and their current attributes.

Along Icon ArrowThe final direction is the same as the Find Target icon arrow. NoteWhen using this option, arrows appear on the Find Target icon to indicate the

direction particles will use for docking. You can change the docking direction by reorienting the icon. This applies even when using mesh objects as targets.

Icon SphericalThe final direction points toward the center of the operator icon.

NoteWhen using this option, arrows appear on the Find Target icon to indicate the directions particles will use for docking. You can change the docking directions

by reorienting the icon. This applies even when using mesh objects as targets. Icon CylindricalThe final direction points toward the icon arrow as a line, thus

forming a cylindrical field with the arrow as the cylinder's main axis.

NoteWhen using this option, arrows appear on the Find Target icon to indicate the directions particles will use for docking. You can change the docking directions

by reorienting the icon. This applies even when using mesh objects as targets. Surface NormalsEach particle reaches its target point from a direction

perpendicular to the surface at that point.

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NoteWhen using this option, arrows appear on the Find Target icon to indicate that particles will use surface normals for docking; the actual directions they will

use depends on the target surface. This applies even when using mesh objects as targets.

Distance

The distance from the target at which particles begin docking behavior. This includes the docking direction, and, when using Control By Time, the docking speed.

Icon Size Set the size of the Find Target icon. This affects particle behavior when using the icon as the target.

Color Coordinated When on, the Find Target icon uses the color of the event containing the test as defined by

its local Display operator, if one exists. This applies even if the Display operator is turned off. When off, the Find Target icon uses the default Test Gizmos color as defined in

Customize User Interface Colors Particle Flow. Default=on.

Turn on Color Coordinated to make it easier to spot the Find Target icon, because the particles in the event use the same color as the icon.

Uniqueness group The Uniqueness setting enables randomization of the Random options and the Variation options. Seed

Specifies a randomization value. New

Calculates a new seed using a randomization formula. Birth Texture Operator

The Birth Texture operator uses an animated texture to calculate the timing, location, and scale of

particles. In general, Birth Texture causes particles to emit from the object where the texture is white or a bright color.

The Birth Texture operator controls are available in two areas of 3ds Max. First, the Birth Texture rollout, which appears in Particle View, regulates the overall timing of particles. Second, adding a Birth Texture operator to a Particle Flow system creates a 3D icon, or helper,

that you can select in viewports. The icon is placed at the world origin (0,0,0). When you select this icon, the Parameters rollout opens on the Modify panel. These controls let you specify the

timing, placement, and scaling of particles. You can also access the Birth Texture operator's parameters via the operator in Particle View, by clicking Initialization Parameters.

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To use the Birth Texture operator: 1. Create an object, and apply a material to it that includes an animated map with variations

of light and dark colors. For example, you could apply a Checker map as the Diffuse map with an animated Offset parameter.

2. Create a PF Source.

3. In Particle View, replace the Birth operator with a Birth Texture operator. This creates the Birth Texture icon at the world center: 0,0,0.

4. On the Birth Texture rollout in Particle View, set Emit Stop to 100 (or any other value you prefer) and turn off Lock To Emitters.

5. Click Initialization Parameters. This selects the Birth Texture icon and opens the Modify

panel. 6. On the Modify panel, in the Timing group of controls, set Stop to the value you used in

step 4. 7. In the Emitter Objects group, select the object with the material as the emitter. 8. At the top of the Parameters rollout, click Initialize Particle Emission.

This process runs through the animation, and places particle seeds (white) on the object's surface where white or light areas appear.

TipIf no particles appear, try turning down the Whiteness setting in the Emission By group. This lowers the threshold of texture brightness required to emit particles.

9. In Particle View, remove or disable the Position Icon operator and then play the

animation. The seeds turn into particles whenever the area under the seeds turns white; the particles then move away from the object.

Interface Birth Texture rollout

This rollout appears in Particle View when the Birth Texture operator is selected. Emit Start

The frame at which the operator begins emitting particles.

Emit Stop The frame at which the operator stops emitting particles. The exact timing of start and

stop may vary due to the timing of individual particles, which depends on the emitter's animated texture.

Reset To Original Timing

Sets the Emit Start and Emit Stop values to the current values of Timing Start and Stop as initialized (that is, when you last clicked Initialize Particle Emission). If Emit

Start and Emit Stop differ from the original timing, the particle timing is scaled to fit into the emission interval. This lets you change the overall timing of the emission without the

long process of pre-calculation. Lock On Emitters

Causes all particle pivot points to be "glued" to the emitter objects. This control is similar

to the Lock On Emitter option of the Position Icon operator. It tells the Birth Texture operator to continue controlling particle position even after the particles are born.

Total Particles This read-only value shows the total number of pre-calculated particles. The amount of particles actually generated depends on the Quantity Multiplier of the master PF Source

object. If the multiplier value is less than 100%, the operator samples the pre-calculated particles. If the multiplier is greater than 100%, some particle seeds are able to generate

multiple particles.

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Initialization Parameters Selects the Birth Texture icon and switches to the Modify panel to show controls related

to the particle timing and placement pre-calculation (see following). Parameters rollout This rollout is available on the Modify panel when you select the Birth Texture icon or click

Initialization Parameters (see preceding). [concentric color box]

The color of this icon indicates the calculation status of particle seeds. When blue-green, the operator has generated particle seeds according to the current set of parameters, and is up to date. When red, parameters have been changed since the last initialization, and you

must update the particle seeds by clicking Initialize Particle Emission. Initialize Particle Emission

Click to calculate particle seed timing, placement and scaling according to the current set of parameters. If the emitters geometry or textures are complex, the initialization process can be lengthy. The overall progress of calculation is indicated as a percentage in the

status bar. When calculation is complete, the Green/Red concentric color box turns green. This option is available only after you have picked at least one emitter in the Emitter

Objects group. Quantity group The Birth Texture operator offers several methods for determining the quantity and placement of

particle seeds. In general, each of these methods covers the emitter with the maximum number of particle seeds allowed for the chosen method, then the texture's coloring or brightness defines if and when a seed is converted to a particle.

NoteThese parameters control particle seeds, not the particles themselves. A particle seed is converted to a particle based on the parameters in other rollouts, and on the color and brightness

of the texture itself. Choose one option in this group:

AmountRandomly covers the emitter surface with the specified number of particle seeds.

Then the animated texture is used to define if and when a seed generates a particle. This option can be used when you don’t want particles to be generated in the same place

multiple times when the texture is animated. Max. RateSets the maximum number of particles that can be generated per frame over the

entire surface, when the texture color exceeds the Whiteness value. The rate is expressed

in particles per frame. First, the emitter surface is randomly covered with seeds at the Max. Rate, starting with the Start frame. Then the texture for the current frame defines at

that frame whether each seed generates a particle. The unused seeds are not used. At the next frame, a new set of particle seeds is generated. This option generates particle seeds in this manner from the Start frame to the Stop frame. This option can be used when it

doesn't matter whether particles are generated in the same place multiple times. SeparateSets the distance by which particle seeds are separated, in units. The emitters

surface is evenly covered with particle seeds, and the seeds are placed in such a way that they are separated by the Separate value. Then the animated texture is used to define if and when a seed generates a particle. The Separate option guarantees the absence of dense

clusters and overlapping particles. This option guarantees that particles will not be generated in the same place multiple times.

When you choose Separate, two additional options become available: o Adjust By Scale FactorWhen the Separate option is chosen and you’ve specified a

Scale Factor option other than None, this option adjusts the separation distance

according to particle scale. In other words, when Adjust By Scale Factor is on,

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Particle Flow can place smaller particles closer together, while increasing the distance between larger particles.

o Fast Approx. Separation Vertices/EdgesPlaces particle seeds on surface vertices. The total amount of particle seeds

is defined by the number of vertices.

o SubdividePlaces particle seeds on visible edges as well as vertices. The seeds are distributed evenly along edges, spaced by a distance approximately equal to the

Subdivide value. Then the animated texture is used to define if and when a seed generates a particle. The total amount of particle seeds is defined by the number of vertices, and the lengths of visible edges.

FacesPlaces particle seeds at face centers. If the Subdivide option is on then each face is subdivided to a point when every faces edge is less then the Subdivide value, and a

particle seed is placed at the center of the sub-faces. Then the animated texture is used to define if a seed generates a particle, and when. The total amount of particle seeds is defined by the number of faces and their size (if Subdivide is on). The Faces option with

Subdivide on generates the most evenly distributed particles over the emitter surface, with some regular properties. If the Subdivide value is less then a particle size then the

particles are able to cover the entire emitter surface without any holes. o SubdivideThe option is available for the Vertices/Edges and Faces amount types

only. When On, edges and faces are subdivided to generate the greater amount of

particles. Amount Limit

This control is available if you choose Vertices/Edges or Faces and also turn on

Subdivide. Small values of Subdivide can generate so many particle seeds that they exceed available memory: this value limits the number of seeds, so 3ds Max doesn’t hang.

Range = 10 to 50000000 (fifty million). Default=1000000 (one million). Total Amount

This read-only value shows the total number of particles pre-calculated for the emission.

Because the animated texture might not reach required whiteness level over the emitter surface, this value is usually smaller then Amount or Max. Rate*(Stop-Start) values.

Timing group These parameters determine the time interval over which particles are generated. The operator analyzes the emitter texture over the time interval, using the data to define the precise birth

moment for each particle. The timing for each particle is stored as a floating-point value ranging from 0.0 to 1.0. This indicates its timing relative to the start (0.0) or end (1.0) of the interval and

makes it possible to adjust the overall timing of the particle emission without recalculation. You can also adjust particle timing in Particle View by changing the Emit Start and Emit Stop values.

Start The first frame of the interval over which particles are generated.

Stop The last frame of the interval over which particles are generated.

Delay Var

Variation in particle emission, in frames. Latency

Causes particle seeds to accumulate brightness over time, and to be converted to particles only if they accumulate a certain brightness value. The Latency value is multiplied by the Whiteness % value to determine the whiteness that needs to be achieved. Then particle

seeds accumulate Luminance values for the texture at each frame, and are converted to

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particles when they achieve the multiplied whiteness value. Latency can be used to cause a sweep of particles to be generated over a gradient map without having to animate the

map. For example, if Latency is off, Whiteness is 100%, and the texture where a particle seed resides is white [256,256,256], a particle will be generated. But if Latency is on and set to

3, the multiplied whiteness required to convert to a particle is 300%, which the particle seed accumulates after 3 frames.

Following are more examples of how adjusting Latency affects how particles are generated:

Texture color=[128,128,128] (50% brightness); Whiteness=100%; Latency=7:

The particle seed requires 700% brightness to emit a particle, which would be achieved after 14 frames.

Texture color=[32,32,32] (12.5% brightness); Whiteness=50%; Latency=2: The particle seed requires 100% brightness to emit a particle, which would be achieved after eight frames.

Precision The level of accuracy for particle timing calculation. If the texture has more than a single

image per frame, to include the sub-frame images choose a sub-frame sampling method. The available choices are Frame, Half Frame, 1/4 Frame, 1/8 Frame.

Emission By group

Particle seeds are converted to particles when the particle seeds are located on an area of the texture that exceeds the Whiteness value. The parameters in this group define how Particle Flow interprets the texture information to see if it exceeds the Whiteness value.

The Emission By choices are as follows: MaterialGathers colors from the emitter's material.

Sub-MaterialGathers colors from a single sub-material, and generates particles only on faces with the specified sub-material ID (Material ID). The sub-material ID is set by the Sub-Mtl ID parameter (see following).

Sub-Mtl GlobalGathers colors from a single sub-material, and generates particles over the entire emitter surface regardless of the faces' Material IDs. The sub-material ID is set by

the Sub-Mtl ID parameter (see following). Vertex ColorGathers colors from the Vertex Color channel. Vertex AlphaGathers colors from the Vertex Alpha channel.

Vertex IllumGathers colors from the Vertex Illum channel. MappingGathers colors from a mapping channel. A mapping channel can be used by the

Vertex Paint modifier to color vertices. The mapping channel index is defined by the Channel parameter.

TipFor information about these channels, see the VertexPaint Modifier topic in the 3ds Max

Help. R/G/B

These buttons let you define the set of color channels to be considered for particle generation. For example, if only the R (red) button is active, then only the red color data is used to determine whether particles are generated. If more then one button is active, the

average of the chosen channels is used. Sub-Mtl ID

Specifies the sub-material ID when Emission By (see preceding) is set to Sub-Material or Sub-Material Global. Typically the sub-material is a component of a Multi/Sub-Object material, and you can find the IDs on the material’s Basic Parameters rollout.

Whiteness %

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Sets the color trigger level. If a color at a particle seed location exceeds this threshold, then a particle is generated. A 0% Whiteness corresponds to RGB value (0,0,0), while a

100% Whiteness corresponds to the RGB value (255,255,255). Emitter Objects group Use these controls to assign objects to be used as particle emitters.

Add Adds an object to the list.

By List Opens the Select Emitter Geometry dialog where you can add multiple objects to the list.

Remove

Removes a highlighted object from the list. Animated Emitters

Indicates that the emitter objects are animated, either with transforms or surface animation. This option affects the display of particle seeds, but doesn’t affect particle generation, because all particles are generated on the surface regardless of whether it is

animated. Toggling this option does not affect calculation status. Surface Normal Offset

When on, lets you specify an offset range from the emitter surface for particle placement. Negative values place particle seeds below the surface.

Offset Min/Max

When Surface Normal Offset is on, you can specify the range of offset distance from the object surface. The Min value cannot exceed the Max value, and the Max value cannot go below the Min value.

Scale Factor group The operator can initialize particle scaling according to the characteristics of the texture the

particles are generated from. So, for example, you can vary the sizes of particles emitted from different parts of the surface with a gradient map. The scale value calculation uses the texture's state at the current frame, disregarding any animation the texture has. Since a color has three

floating-point values, each value defines a different component of the scale vector. To have a uniform scale factor, use textures with no hue (black/gray/white gradients).

Scale By Defines the source of color to calculate particle scaling. The available choices are:

NoneNo particle scaling is set.

Sub-MaterialUses a single sub-material to set the scale, and uses this scale over the entire emitter surface regardless of the faces' Material IDs. The sub-material

ID is set by the Sub-Mtl ID parameter. Vertex ColorUses the Vertex Color channel to define particle scale. Vertex AlphaUses the Vertex Alpha channel to define particle scale.

Vertex IllumUses the Vertex Illum channel to define particle scale. MappingDefines particle scale with a mapping channel that is used for vertex

coloring by the Vertex Paint modifier. The mapping channel index is defined by the Channel parameter.

TipFor information about these channels, see the VertexPaint Modifier topic in the 3ds

Max Help. Sub-Mtl ID

When Scale By (see preceding) is set to Sub-Material, specifies the sub-material ID. Typically the sub-material is a component of a Multi/Sub-Object material, and you can find the IDs on the material’s Basic Parameters rollout.

Black Scale %

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Defines the scale value for particles that fall on pure black areas of the texture. This value should be used to set the scale percentage for the smallest particles in the range. The

Black Scale % must be lower than or equal to the White Scale %. White Scale %

Defines the scale value for particles that fall on pure white areas of the texture. For

intermediate gray colors, the scale value is linearly interpolated between the Black Scale % and White Scale %.

The Black Scale % and White Scale % can influence the particle distribution if the Separate option in the Quantity group is chosen, and Adjust By Scale Factor is on.

Display group

The operator is able to show the particles in interactive, non-history-dependent mode. Usually, if you want to see particle animation, you have to place the operator into an event that is wired to an

active PF Source event. However, this might require heavy calculation for history-dependent particle animation. The parameters in the Display group give you the ability to see how particles will be created without the overhead of generating a particle system.

Show Particles Displays calculated particle seeds as ticks.

All / By Timing Defines the mode for showing particles:

AllAll pre-calculated particles are shown.

By TimingEach particle is displayed at the frame at which it will be born. The timing shown with the By Timing method might differ from the actual particle emission because the Emit Start and Emit Stop values in the Birth Texture

operator can adjust the overall particle timing. Only When Selected

When on, particle seeds appear in the viewports only when the Birth Texture icon is selected. When off, particle seeds always appear.

Icon Size

Sets the size of the 3D icon of the operator. The size of the icon has no effect on particle size or emission.

Color Coordinated When on, the color of the 3D icon is synchronized with the color set by the Display operator in the same event as the corresponding Birth Texture operator. When off, the

icon uses the standard Particle Flow operator color: blue. Uniqueness group

The Uniqueness settings enable you to change the randomization of the particle generation where appropriate. Seed

Specifies a randomization value. New

Calculates a new seed using a randomization formula. Group Selection Operator

The Group Selection operator extends Particle Flow's ability to select particles. Originally in

Particle Flow, you select a single group of particles explicitly that remains selected throughout the entire flow. With Group Selection, however, you can specify any number of groups according

to various criteria: location, particle properties, at random, and more. You can divert selected particle groups to another event with the Split Group test, or indicate an outside event to affect particles with the Group Operator. The Group Selection icon can be scaled

and transformed to change the particle selection dynamically over the course of the particle flow.

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You can instance the Group Selection operator in different events to define the same selection subset. If the particles converge into another event, the selection subsets are united, and a Group

Operator works with the combined selection subset. The Group Selection operator doesn't change particle properties. It adds a data channel that indicates the selection status of a particle corresponding to the selection operator. To modify

particles based on their selection status, use a Group Operator or Split Group test. Group Selection icon

Adding a Group Selection operator to a Particle Flow system creates a 3D icon, or helper, that you can select in viewports. The icon is placed at the world origin (0,0,0). When you select this icon, the Parameters rollout opens on the Modify panel that provides the controls described in the

following section. The position of the icon is used by Particle Flow when you choose the Inside Icon Volume option.

Selection Update

Choose how to calculate the selection status: OnceThe operator determines the selection status only once, at the time a particle

enters the event. ContinuousCalculates the selection status anew at every frame.

Depending on other options, the Group Selection operator may detect the selection status change in between frames, on sub-frame sampling basis.

Reverse Selection

Inverts the particle selection. Selection Condition

Determines the method the operator uses to select particles. The choices are as follows:

Entire Particle StreamSelects all particles in the event. Use this option if particle selections are merging in the current event, and in a later event you plan to separate particles with an instanced

Group Selection operator. By SnapshotSelects particles based on those currently selected in the PF Source sub-object level, or all particles present in the event at the current frame. The number of selected particles appears

next to By Snapshot. To select the particles, choose one of the following sources from the dropdown menu and then

click Generate Snapshot: in PF SourceSelects the particles currently selected at the Particle sub-object level of the

PF Source. Before using this option, make sure both of the PF Source object's Quantity

Multiplier settings (Viewport % and Render %) are the same. All in Current EventSelects all particles in the event at the current frame.

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Generate SnapshotClick to select the particles as specified by the choice in the drop-down list. The number of selected particles appears next to By Snapshot.

Once you have generated a snapshot, you can change the frame or sub-object particle selection without affecting the selection in this Group Selection operator. Keep in mind that the selection is based on the particle IDs. Therefore, if the number of

particles in the viewport and the rendering are different, the overall effect can differ drastically. To use this type of selection effectively, synchronize the percentage of

particles in the viewport and renderer. Inside Icon Volume Displays the Group Selection icon in the viewports, and selects all

particles within the icon. If Selection Update (see preceding) is set to Once, only particles

that are inside the icon at the start of the event are selected. If Selection Update is set to Continuous, particles are members of the group only when present inside the icon

volume; thus, the selection can change throughout the animation. Icon TypeSets the overall shape of the icon: Box, Cylinder, or Sphere. The initial size of

the icon is set by the Icon Size parameter, near the bottom of the rollout. To change the

icon size and shape, change this parameter or use either uniform and non-uniform scaling . You can also move, rotate, and animate the icon to change the selection area.

Subframe SamplingWhen off, the motion of the icon or the reference object is considered to be linear between frames. If the icon or the object has fast, complex motion, turn on this option for greater precision in the calculation of the icon/object location.

NoteThis setting also applies to the Inside Object option (see following). Inside ObjectLets you designate an arbitrary object as the volume for selecting particles

for the group. After choosing this option, click the “None” button and then select a

reference object to use as a selection bounding area. All particles inside the reference object are selected. If the object doesn't define a closed space, the resulting selection

might not be consistent. NoteThe Subframe Sampling option (see preceding) applies to Inside Object as well as Inside Icon Volume.

Animated ShapeIf the reference object is animated in a way that changes its shape or volume, turn on this option.

By Particle PropertyUses particle properties to define the selection set. This choice appears in parentheses in the event, after the operator name. From the Property list, choose one of the following:

o AgeUses particle age to define the subset. All particles with ages in the From/To range become selected. Use the Variation parameter to vary the selection status.

o Birth IDUses a unique particle ID is used to define the subset. All particles with IDs in the From/To range become selected. Use the Variation parameter to vary the selection status.

NoteThe Birth ID property is not scalable in reference to the Quantity Multiplier parameters of the PF Source object.

o DirectionUses the particle speed vector and the icon direction vector to determine the selection subset. Particles are selected if their speed vectors are close in direction to the icon vector. When this option is selected, the icon shows an arrow with a

surrounding cone to show the effects of the Divergence parameter. All particles with a speed vector within the cone become selected. The Divergence and Variation

parameters are expressed in degrees. o ScaleUses particle scale value to define the selection subset. Since the scale value is a

vector, and From and To values are scalar, the maximum value of the scale

components is used to define the range inclusion.

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o Script FloatUses a particle float data channel to define the selection subset. The Float data channel is usually controlled by a Script operator.

o SizeUses particle size to define the selection subset. Particle size is controlled by Shape and Scale operator parameters. As with the Scale option, the operator uses the maximum value of the size vectors components to define the range inclusion.

o SpeedUses particle speed to define the selection subset. The From, To, and Variation parameters are defined in units per second.

o Uniform IndexA scalable particle ID parameter. If the Quantity Multiplier is set to 100%, then the Uniform Index is the same as the Birth ID index. If the Uniform Index parameter is used, then the area with selected particles is consistent regardless of the

Quantity Multiplier parameters. Randomly SelectedSelects particles at random. The Chance % parameter defines how many

particles will be selected. 100% means that all particles are selected; 50% means that roughly half of the particles are selected.

Combine GroupsSelects particles using a combination of the selection subsets defined by

other Group Selection operators. Buttons A and B define the other Group Selection operators. The available combinations are:

o A and BA particle is selected if it is selected by both operators A and B. o A or BA particle is selected if it is selected by operator A or operator B. o A or B not bothA particle is selected if it is selected by operator A but not by operator

B, or vice-versa. o A and not Ba particle is selected if it is selected by operator A but not by operator B.

Icon Size

Sets the size of the 3D icon. Available only for the selection conditions Inside Icon Volume and Select By Particle Property: Direction.

Logo Size Sets the logo size, which has no effect on particles.

Color Coordinated

When on, the color of the 3D icon is synchronized with the Display operator in the current event. When off, the icon has a standard Particle Flow operator color (blue).

Uniqueness Group These controls set randomization for the Randomly Selected and Select By Particle Property selection conditions.

Seed Specifies a randomization value.

New Calculates a new seed using a randomization formula.

VRML97 Helper Objects

The VRML97 helpers let you create online 3D scenes and interaction using Virtual Reality Markup Language. Insert a VRML 97 Helper into the scene by clicking and dragging at the

desired location. NoteSome helper objects (for example, Billboard and Level Of Detail) are position-sensitive, so be careful how and where you insert them. Usually, you have the most control by creating the

helper object in the Top viewport. Anchor VRML97 Helper

The Anchor helper lets you specify a click-to-play trigger in the scene. This trigger will be linked to a currently existing object in the scene. This allows you to add links to other HTML pages, VRML97 worlds, or alternate cameras in your VRML97 world.

Procedures

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To set up an Anchor to jump to another VRML world: 1. Add an Anchor helper object by clicking the Anchor button and then dragging in the Top

viewport to create its icon. 2. Pick a Trigger Object in the scene that will be the object the viewer clicks while

browsing.

3. Choose Hyperlink Jump and designate a URL to jump to. 4. When the user clicks the Trigger Object geometry, the browser will replace the current

scene with the designated URL. The Anchor rollout contains the following options:

Pick Trigger Object Specifies the geometry that will be the trigger for this anchor. Click this button, then

select the geometry. Description

Lets you enter a text description or message that will appear in the browser's status bar

when the mouse is over an object that has an Anchor action defined for it. Hyperlink Jump

Creates an Anchor that jumps to a URL. URL

Specifies the location for Hyperlink Jump. Use your Bookmarks list, or enter a location

manually. If the URL points to another VRML97 world (a .wrl file) you can append "#CameraName" to the end of the URL to have the browser use the viewpoint named "CameraName" as the initial view.

Bookmarks Lets you select a URL location from a list of bookmarks. Click Import List to import the

list of bookmarks defined in your browser, or manually enter new URLs into the list. Parameter

Lets you specify additional browser parameters for the hyperlink jump.

Set Camera Creates an Anchor that jumps to a given camera in the current VRML97 world.

Camera Specifies the name of the camera for Set Camera.

Icon Size

Determines the size of the helper in the scene. Background VRML97 Helper

The Background helper has Sky Color, Ground Color, and Images rollouts. Use these rollouts to specify colors and images for the sky and ground in your VRML97 world. Procedures

To create a Background helper object: 1. Add a Background helper object by clicking the Background button, then click-drag in the

Top viewport. 2. Use the controls to adjust the colors and layout of the background.

Interface

Sky Colors rollout Lets you provide a colored background to the world’s sky using a gradient of up to three colors.

The sky is an infinite sphere that encloses the objects of the scene. Number of Colors

Specifies whether the sky is one solid color or a gradient of two or three colors.

Color One/Two/Three

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Lets you select the colors from the Color Selector. Color One is the base color. Angle

Specifies the angle at which Color Two and Color Three merge with the base color, in degrees from the North pole of the sky (straight up from the viewer).

Icon Size

Adjusts the size of the helper object in the viewports. Ground Colors rollout

Lets you provide a colored background to the world’s ground plane using a gradient of up to three colors. The ground appears inside the sky sphere and below the objects of the scene. Number of Colors

Specifies whether the ground is one solid color or a gradient of two or three colors. Color One/Two/Three

Lets you select the colors from the Color Selector. Color One is the base color. Angle

Specifies the angle at which Color Two and Color Three merge with the base color, in

degrees from the South pole of the sky (straight down from the viewer). Images rollout

Lets you specify a set of images that define a background panorama between the ground/sky backdrop and the objects in the scene. The panorama consists of six images, each of which is mapped onto a face of an infinitely large cube centered in the local coordinate system.

Image URLs Specifies the location/file names of the images to use. The images can be JPEG files or PNG files with or without transparency. Some browsers also support GIF files.

Fog VRML97 Helper

The Fog helper lets you specify the color and range of fog in your VRML97 world. You can

simulate atmospheric effects by blending objects with a color based on the objects' distances from the viewer. For the best visual results, the background (which is unaffected by the fog) should be the same color as the fog.

Procedures To create a VRML 97 Fog helper:

1. Add a Fog helper by clicking the Fog button, then click-drag in the Top viewport to create its icon.

2. Use the controls to adjust the type of fog in your VRML environment.

Interface The Fog rollout contains the following options:

Type Specifies the fog type (linear or exponential). Linear means that the amount of blending is a linear function of the distance, resulting in a depth-cueing effect. Exponential uses an

exponential increase in blending, resulting in a more natural fog appearance. Color

Lets you select the fog color from the Color Selector dialog. Visibility Range

Specifies the distance from the viewer at which objects are totally obscured by the fog.

The smaller this value is, the closer the fog is to the camera, and the less your scene is visible. The larger this value is, the more of your scene is visible to the camera. A value of

0 turns off the effect, making everything in the scene visible. A value of 0 means that there is no fog effect.

Icon Size

Adjusts the size of the helper object in the viewports.

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LOD VRML97 Helper

The Level of Detail (LOD) helper lets you specify objects with varying face counts that are

appropriate for different viewing distances. Browsers display the less detailed objects when the viewer is far away from them and substitute the more detailed objects at closer ranges. Use LOD objects to speed up rendering of scenes in which highly detailed objects are often far

away from the viewer. Objects used for LOD do not have to be of the same type or size, so you can accomplish a crude

form of morphing by using different objects as the LOD components. For example, a tree might seem to grow if taller trees with more limbs are substituted as the viewer gets closer. Procedures

To create a Level of Detail helper object: 1. Create the objects to which you want to add level of detail.

2. Click the LOD button. 3. Click and drag in the scene to create a helper object. 4. Add the objects to the list with Pick Objects.

5. Use the Hide and Unhide commands, or the H key, to help pick the objects and add them to the LOD list.

6. Select the objects in the list and use the Distance spinner to set the distance. To create all the objects and the LOD helper object at exactly the same coordinates:

1. Create the LOD helper object.

2. You can use Snap and create the helper object at the origin (0,0,0 coordinates), or use the Keyboard Entry rollout for a Standard Primitive to specify an exact object origin.

3. Create the object with the most detail at the same coordinates. Name it (for example,

hicapsule). 4. Choose Edit/Clone.

In the Clone Options dialog, choose Copy and name the new object (for example, medcapsule).

5. Repeat step 3 to create the other objects (for example, locapsule).

For the medium and low resolution objects, apply an Optimize modifier to reduce the face count.

For primitives, you can reduce the face count by changing the creation parameters in the modifier stack.

Interface

The Level of Detail rollout contains the following options: Pick Objects

Selects objects of different face counts to substitute for the LOD helper object. Create all the objects and the LOD helper object at exactly the same coordinates.

Distance

Sets the distance from the camera at which the user sees the selected object. The distance specified for the object appears next to the object name. For example:

hicapsule - 100 medcapsule - 300 locapsule − 500 Hicapsule is displayed when the distance between it and the camera is within 100 units. The lower resolution object (medcapsule) is displayed when the camera is between 100

and 300 units. The lowest resolution object (locapsule) is displayed when the camera is beyond 300 units. The greatest distance (500 in this case) is not actually used, but must be

supplied. Delete

Deletes the selected object from the list.

Icon Size

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Sets the size of the LOD helper object. ProxSensor VRML97 Helper

The ProxSensor helper creates a VRML97 ProximitySensor node. This lets you set up a rectangular region in space, so that entering the region in a VRML97 browser starts a set of objects animating.

Procedures To create a Proximity Sensor object:

1. Add a Proximity Sensor object by clicking the ProxSensor button and then click-dragging in the Top viewport to create its icon.

2. Select the geometry, camera, or sound to control.

When the user navigates inside the box, the specified objects animate or the sound plays. The Prox Sensor rollout contains the following options:

Length/Width/Height Specifies the dimensions of the bounding box that triggers the action.

Enable

Activates the Proximity Sensor. When this check box is turned off, the sensor has no effect, even if objects have been selected.

Pick Action Objects Specifies the objects in the scene to control with this helper. The objects can be animated geometry, cameras, lights, or AudioClips. Click this button then click the objects in the

viewports. Delete

Deletes an object from the list of picked objects.

TimeSensor VRML97 Helper

The TimeSensor helper lets you add time-based animation controls, such as the start and end

frames for a particular object's animation, and looping. Use this helper to split up an object's animation keys over several triggers, to automatically start an animation upon loading the .wrl file, or to make animation endlessly loop.

Procedures To assign an object to a TimeSensor helper:

1. Add a Time Sensor object by clicking the Time Sensor button and then click-dragging in the Top viewport to create its icon.

2. Press Pick Objects and select the (animated) geometry to control.

3. Use the controls to adjust the start and end times of the animation, and to loop the animation.

Interface The Time Sensor rollout contains the following options: Loop

Repeats the animation from the start-time frame to the stop-time frame. Start on World Load

Starts the animation so that it will be running when the file is loaded into the browser. NoteThis option is only available when Loop is turned on. Otherwise, the animation will start and stop at the specified times.

Start Time/Stop Time Specifies the range of frames to play.

NoteIf the start time is after the end time, the animation will play from the earliest frame to the last frame. It will not play the animation backward.

Pick Objects

Lets you select the objects to control with this TimeSensor.

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Delete Deletes an object from the list of picked objects.

Icon Size Adjusts the size of the helper object in the viewports.

AudioClip VRML97 Helper

The AudioClip helper lets you specify the name and characteristics of an audio file that can be used by the Sound helper.

Procedures To create an AudioClip helper:

1. Click the AudioClip button, and click-drag in the Top viewport to create the helper.

2. Enter the location of the sound file (.wav or .mid) you want to use in the URL text box. Interface

The rollout contains the following options: URL

Specifies the location/file name of the sound to use. Either.wav (waveform) or .mid

(MIDI) files can be used, but MIDI sound files may not be spatialized. Some browsers do not support MIDI.

Description Lets you enter a text description of the sound, which is displayed by some browsers.

Pitch

Sets the relative pitch of the sound. 1.0 is normal pitch, and 0.5 is one octave lower than normal.

Loop

Repeats the sound. Start on World Load

Starts playing the sound as soon as the world is loaded into the browser. Icon Size

Determines the size of the AudioClip helper in the scene.

Billboard VRML97 Helper

camera-aligned in the VRML97 browser. The objects always align to the viewpoint in the

VRML97 browser. Any geometry linked to the Billboard helper will rotate about the local Z axis of the helper object to face the viewer. Since it rotates about the location of the Billboard, it is best to center the

Billboard on the object that you will link to it. The direction of the negative Y axis of the object, which will be its front, is aligned with the

negative Y axis of the helper, and will be the Billboard surface that always faces the viewer. This is the side usually seen from the default camera position. Procedures

To create a Billboard helper object: 1. Click the Billboard button and click-drag in the Top viewport to create the helper.

2. Link objects to the billboard to keep them aligned with the camera. Interface The Billboard rollout contains the following option:

Screen Alignment Keeps the geometry linked to the Billboard helper aligned, even when the viewer elevates,

pitches, and rolls. Icon Size

Determines the size of the Billboard helper in the scene.

Inline VRML97 Helper

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The Inline helper lets you reference another VRML97 file that is included in your world when

you load it into your VRML97 browser. These inline objects are like instance objects, but they function at the browser level. Procedures

To create an Inline helper object: 1. Click the Inline button.

2. Click and drag in one of the viewports. You can modify the helper object with the tools in the VRML Inline rollout.

Interface

If you create the objects in the scene to be inserted off-center (away from the origin), they will appear in the browser off-center as well. Align the original scene and the scene to be inserted

correctly, in relation to the origin. The VRML Inline rollout contains the following options: Insert URL

Specifies the URL of the .wrl files to insert in place of the helper object. The URL must be another VRML97 file.

Bookmarks Displays a dialog that lets you select a location from a list of bookmarks. Click Import List to import the list of bookmarks defined in your browser. Most browsers store

bookmarks in a file called bookmark.htm. Bounding Box

Specifies whether an explicit bounding box size will be exported. If you select “Use Icon

Size,” the diameter of the icon will be written into the VRML97 file for the width, length, and height of the bounding box; the actual contents of the inline file should fit within that

bounding box. If you select “Calculate in Browser,” no bounding box size is exported and the VRML browser will determine the size of the inline geometry.

Icon Size

Sets the size of the helper object. You can transform this object like any other object in 3ds Max. The scene that replaces the helper object will be moved, rotated, or scaled in the

same manner. The size shown is the radius of the icon. NavInfo VRML97 Helper

The NavInfo helper lets you create a VRML97 NavigationInfo node. This tells the browser how

to navigate around the VRML97 world. Procedures

To create a NavInfo helper: 1. Add a NavInfo helper by clicking the NavInfo button and then click-dragging in the Top

viewport to create its icon.

2. Use the controls to adjust the behavior of the helper. Interface

The NavigationInfo rollout contains the following options: Type

Specifies the type of movement (Walk, Examine, Fly, and None) for navigating the

world. Implementation of these movement types may vary from browser to browser. Headlight

Places a directional light at the viewpoint. The light always points in the direction the user is looking. TipDon’t use this option if you have lights in the scene.

Visibility Limit

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Sets the far clipping plane. Any geometry beyond this point is invisible. The smaller this value is, the closer the clipping plane is to the camera. The larger this value is, the more of

your scene is visible to the camera. A value of 0 turns off the effect, making everything in the scene visible. Use this option to show just part of large scenes.

Speed

Determines the speed of navigation in units per second. Use this option to allow the user to travel faster, if you’re building a large world (like a cityscape), and slower, if you’re

building a small world (like a room). Avatar Size

Specifies the user's physical dimensions in the world, to detect collision distance and

follow terrain. Collision

Specifies the allowable distance between the user's position and any collision geometry before a collision is detected. For example, you can set this so that a collision is detected one unit in front of a wall.

Terrain Specifies the height above the surface to maintain when following terrain.

Step Height Specifies the highest object that can be "stepped over." If an object like a staircase has steps that are lower than this value, the user can go up.

Icon Size Adjusts the size of the helper object in the viewports.

Sound VRML97 Helper

The Sound helper lets you place 3D (spatial) or ambient sounds in a scene. The sound can be located at a point and emit sound in a spherical or ellipsoid pattern. The

ellipsoid is pointed in a particular direction and may be shaped to provide more or less directional focus from the location of the sound. The sound node can also be used to describe an ambient sound that tapers off at a specified distance from the sound node.

The red ellipsoid of the helper represents the outermost range for which the sound can be heard. The blue ellipsoid represents the range of the maximum strength of the sound. The area between

the red and blue ellipsoids represents a falloff area in which the volume varies in intensity. The helper's arrow points in the direction toward which the sound is emanating. NoteThe Sound helper object must be linked to an existing audio clip in the scene. Therefore, you

must have an AudioClip helper object in the scene in order for the Sound helper to play. Procedures

To create a Sound helper object: 1. Add a Sound helper by clicking the Sound button, then click-drag in the Top viewport to

create its icon.

2. Press Pick Audio Clip and select an AudioClip helper object in the scene. 3. Rotate the icon to determine the direction in which the sound is emanated.

4. Use the controls to adjust the range and strength of the playback sound. Interface The Sound rollout contains the following options:

Intensity Sets the loudness of the sound. 1.0 is full volume.

Priority Sets the relative importance of the sound, if you have more than one sound in the scene and the browser cannot play all of them. 0 is least important. 1 is most important.

Spatialize

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Makes the sound 3D. A spatial sound has a particular source location in the scene. If this box is turned off, the sound is ambient.

Min Back/Front, Max Back/Front Displays red and blue ellipsoids that allow you to set the area of the sound effect. Inside the blue ellipsoid, the sound is at full volume. Outside the red ellipsoid, the sound is

inaudible. Between the blue and red ellipsoids is a falloff area in which the volume varies in intensity.

Pick Audio Clip Lets you choose an audio clip. Click this button, then click an AudioClip helper object. The audio clip must already be in the scene and have a sound file associated with it.

Icon Size Determines the size of the helper in the scene.

TouchSensor VRML97 Helper

The TouchSensor helper lets you set up an object so that selecting it in a VRML97 browser starts a set of objects animating.

Procedures To set up an object as a TouchSensor trigger:

1. Add a Touch Sensor object by clicking the Touch Sensor button and then click-dragging in the Top viewport to create its icon.

2. Select the geometry to control.

When the user clicks the trigger geometry, the geometry, camera or light animates, or the sound plays.

Interface

The Touch Sensor rollout contains the following options: Pick Trigger Object

Specifies the geometry that will be the trigger for this TouchSensor. Click this button, then select the geometry.

Enable

Activates the Touch Sensor. When this box is turned off, the sensor has no effect, even if objects have been selected.

Pick Action Objects Specifies the objects in the scene to control with this helper.

Delete

Deletes an object from the list of picked objects. Icon Size

Determines the size of the Touch Sensor helper in the scene.