# Drag Force dynamics node

Applies force and torque to objects that resists their current direction of motion.

The Drag Force DOP applies force and torque to oppose a difference from a goal motion. For solvers that apply forces to objects based on their area, the drag forces are scaled by the area of the object as measured from the direction of the object’s velocity. So a large flat object will not experience much drag if it is moving in a direction perpendicular to the normal of the surface.

Note that drag force is applied independently of the object’s mass. Light objects will be affected more than heavy objects. For a default RBD Object you may want to set the force scale to 1000 so that if the object is roughly unit-sized and has the default density of 1000, and Ignore Mass is off, you would get an acceleration that’s roughly proportional to the difference between the object’s current velocity and its goal velocity.

If the drag value is very large with respect to the timestep, some solvers can experience instability. If you want a stable drag independent of the object’s mass, you can update the velocity explicitly to be a multiple of the current velocity.

You can add noise to the force applied by this DOP by connecting a Noise Field DOP to the second input of this node. Noise is added as subdata of the force data. To avoid changing the Drag force away from the direction of motion, the Noise Field DOP should have Generate Scalar Noise turned on.

## Using Drag Force

1. Select the dynamic object to apply drag force to.

2. Click the Drag Force tool on the Drive Simulation tab.

## Parameters

Ignore Mass

Factor out the mass of the object when calculating the drag force. This causes objects of different masses to receive different forces, which allows them to then change velocity at the same rate.

This is useful if you have a large variety of object sizes and want to apply a consistent drag effect. Note that the torque scale is unaffected by this option - objects will continue to have different changes in rotational speeds as a result of the drag.

Goal Velocity

Applied forces will oppose any difference between an object’s velocity and the Velocity parameter. This can be thought of as the ambient wind direction that speeds up slow objects and slows down fast objects until they match this velocity.

Goal Ang. Velocity

Applied torques will oppose any difference between an object’s angular velocity and the Angular Velocity parameter.

Scale Force

The applied force is equal to the negative of the object’s relative velocity, scaled by the Scale Force parameter.

Scale Torque

The applied torque is equal to the negative of the object’s relative angular velocity scaled by the Scale Torque parameter.

Sampling Mode

Controls how the force is sampled over space. The behavior will vary depending on the solver. Fluid solvers will always sample per-voxel, but RBD solvers can switch between sampling only the centroid, only the surface, or the entire volume.

Parameter Operations

Each data option parameter has an associated menu which specifies how that parameter operates.

Use Default

Use the value from the Default Operation menu.

Set Initial

Set the value of this parameter only when this data is created. On all subsequent timesteps, the value of this parameter is not altered. This is useful for setting up initial conditions like position and velocity.

Set Always

Always set the value of this parameter. This is useful when specific keyframed values are required over time. This could be used to keyframe the position of an object over time, or to cause the geometry from a SOP to be refetched at each timestep if the geometry is deforming.

You can also use this setting in conjunction with the local variables for a parameter value to modify a value over time. For example, in the X Position, an expression like `\$tx + 0.1` would cause the object to move 0.1 units to the right on each timestep.

Set Never

Do not ever set the value of this parameter. This option is most useful when using this node to modify an existing piece of data connected through the first input.

For example, an RBD State DOP may want to animate just the mass of an object, and nothing else. The Set Never option could be used on all parameters except for Mass, which would use Set Always.

Default Operation

For any parameters with their Operation menu set to Use Default, this parameter controls what operation is used.

This parameter has the same menu options and meanings as the Parameter Operations menus, but without the Use Default choice.

Data Sharing

Controls the way in which the data created by this node is shared among multiple objects in the simulation.

Data sharing can greatly reduce the memory footprint of a simulation, but at the expense of requiring all objects to have exactly the same data associated with them.

Do Not Share Data

No data sharing is used. Each object has its own copy of the data attached.

This is appropriate for situations where the data needs to be customized on a per-object basis, such as setting up initial positions and velocities for objects.

Share Data Across All Time

This node only creates a single piece of data for the whole simulation. This data is created the first time it is needed, so any expressions will be evaluated only for the first object.

All subsequent objects will have the data attached with the same values that were calculated from the expressions for the first object. It is important to note that expressions are not stored with the data, so they cannot be evaluated after the data is created.

Expressions are evaluated by the DOP node before creating the data. Expressions involving time will also only be evaluated when this single piece of data is created. This option is appropriate for data that does not change over time, and is the same for all objects, such as a Gravity DOP.

Share Data In One Timestep

A new piece of data is created for each timestep in the simulation. Within a timestep though, all objects have the same data attached to them. So expressions involving time will cause this data to animate over time, but expressions involving the object will only evaluate for the first object to which the data is attached.

This option is appropriate for data that changes over time, but is the same for all objects such as a Fan Force DOP, where the fan may move or rotate over time.

Activation

Determines if this node should do anything on a given timestep and for a particular object. If this parameter is an expression, it is evaluated for each object (even if data sharing is turned on).

If it evaluates to a non-zero value, then the data is attached to that object. If it evaluates to zero, no data is attached, and data previously attached by this node is removed.

Group

When an object connector is attached to the first input of this node, this parameter can be used to choose a subset of those objects to be affected by this node.

Data Name

Indicates the name that should be used to attach the data to an object or other piece of data. If the Data Name contains a "/" (or several), that indicates traversing inside subdata.

For example, if the Fan Force DOP has the default Data Name "Forces/Fan". This attaches the data with the name "Fan" to an existing piece of data named "Forces". If no data named "Forces" exists, a simple piece of container data is created to hold the "Fan" subdata.

Different pieces of data have different requirements on what names should be used for them. Except in very rare situations, the default value should be used. Some exceptions are described with particular pieces of data or with solvers that make use of some particular type of data.

Unique Data Name

Turning on this parameter modifies the Data Name parameter value to ensure that the data created by this node is attached with a unique name so it will not overwrite any existing data.

With this parameter turned off, attaching two pieces of data with the same name will cause the second one to replace the first. There are situations where each type of behavior is desirable.

If an object needs to have several Fan Forces blowing on it, it is much easier to use the Unique Data Name feature to ensure that each fan does not overwrite a previous fan rather than trying to change the Data Name of each fan individually to avoid conflicts.

On the other hand, if an object is known to have RBD State data already attached to it, leaving this option turned off will allow some new RBD State data to overwrite the existing data.

## Inputs

First Input

This optional input can be used to control which simulation objects are modified by this node. Any objects connected through this input and which match the Group parameter field will be modified.

If this input is not connected, this node can be used in conjunction with an Apply Data node, or can be used as an input to another data node.

All Other Inputs

If this node has more input connectors, other data nodes can be attached to act as modifiers for the data created by this node.

The specific types of subdata that are meaningful vary from node to node. Click an input connector to see a list of available data nodes that can be meaningfully attached.

## Outputs

First Output

The operation of this output depends on what inputs are connected to this node. If an object stream is input to this node, the output is also an object stream containing the same objects as the input (but with the data from this node attached).

If no object stream is connected to this node, the output is a data output. This data output can be connected to an Apply Data DOP, or connected directly to a data input of another data node, to attach the data from this node to an object or another piece of data.

## Locals

channelname

This DOP node defines a local variable for each channel and parameter on the Data Options page, with the same name as the channel. So for example, the node may have channels for Position (positionx, positiony, positionz) and a parameter for an object name (objectname).

Then there will also be local variables with the names positionx, positiony, positionz, and objectname. These variables will evaluate to the previous value for that parameter.

This previous value is always stored as part of the data attached to the object being processed. This is essentially a shortcut for a dopfield expression like:

```dopfield(\$DOPNET, \$OBJID, dataName, "Options", 0, channelname)
```

If the data does not already exist, then a value of zero or an empty string will be returned.

DATACT

This value is the simulation time (see variable ST) at which the current data was created. This value may not be the same as the current simulation time if this node is modifying existing data, rather than creating new data.

DATACF

This value is the simulation frame (see variable SF) at which the current data was created. This value may not be the same as the current simulation frame if this node is modifying existing data, rather than creating new data.

RELNAME

This value will be set only when data is being attached to a relationship (such as when Constraint Anchor DOP is connected to the second, third, of fourth inputs of a Constraint DOP).

In this case, this value is set to the name of the relationship the data to which the data is being attached.

RELOBJIDS

This value will be set only when data is being attached to a relationship (such as when Constraint Anchor DOP is connected to the second, third, of fourth inputs of a Constraint DOP).

In this case, this value is set to a string that is a space separated list of the object identifiers for all the Affected Objects of the relationship to which the data is being attached.

RELOBJNAMES

This value will be set only when data is being attached to a relationship (such as when Constraint Anchor DOP is connected to the second, third, of fourth inputs of a Constraint DOP).

In this case, this value is set to a string that is a space separated list of the names of all the Affected Objects of the relationship to which the data is being attached.

RELAFFOBJIDS

This value will be set only when data is being attached to a relationship (such as when Constraint Anchor DOP is connected to the second, third, of fourth inputs of a Constraint DOP).

In this case, this value is set to a string that is a space separated list of the object identifiers for all the Affector Objects of the relationship to which the data is being attached.

RELAFFOBJNAMES

This value will be set only when data is being attached to a relationship (such as when Constraint Anchor DOP is connected to the second, third, of fourth inputs of a Constraint DOP).

In this case, this value is set to a string that is a space separated list of the names of all the Affector Objects of the relationship to which the data is being attached.

ST

This value is the simulation time for which the node is being evaluated.

This value may not be equal to the current Houdini time represented by the variable T, depending on the settings of the DOP Network Offset Time and Time Scale parameters.

This value is guaranteed to have a value of zero at the start of a simulation, so when testing for the first timestep of a simulation, it is best to use a test like `\$ST == 0` rather than `\$T == 0` or `\$FF == 1`.

SF

This value is the simulation frame (or more accurately, the simulation time step number) for which the node is being evaluated.

This value may not be equal to the current Houdini frame number represented by the variable F, depending on the settings of the DOP Network parameters. Instead, this value is equal to the simulation time (ST) divided by the simulation timestep size (TIMESTEP).

TIMESTEP

This value is the size of a simulation timestep. This value is useful to scale values that are expressed in units per second, but are applied on each timestep.

SFPS

This value is the inverse of the TIMESTEP value. It is the number of timesteps per second of simulation time.

SNOBJ

This is the number of objects in the simulation. For nodes that create objects such as the Empty Object node, this value will increase for each object that is evaluated.

A good way to guarantee unique object names is to use an expression like `object_\$SNOBJ`.

NOBJ

This value is the number of objects that will be evaluated by the current node during this timestep. This value will often be different from SNOBJ, as many nodes do not process all the objects in a simulation.

This value may return 0 if the node does not process each object sequentially (such as the Group DOP).

OBJ

This value is the index of the specific object being processed by the node. This value will always run from zero to NOBJ-1 in a given timestep. This value does not identify the current object within the simulation like OBJID or OBJNAME, just the object’s position in the current order of processing.

This value is useful for generating a random number for each object, or simply splitting the objects into two or more groups to be processed in different ways. This value will be -1 if the node does not process objects sequentially (such as the Group DOP).

OBJID

This is the unique object identifier for the object being processed. Every object is assigned an integer value that is unique among all objects in the simulation for all time. Even if an object is deleted, its identifier is never reused.

The object identifier can always be used to uniquely identify a given object. This makes this variable very useful in situations where each object needs to be treated differently. It can be used to produce a unique random number for each object, for example.

This value is also the best way to look up information on an object using the dopfield expression function. This value will be -1 if the node does not process objects sequentially (such as the Group DOP).

ALLOBJIDS

This string contains a space separated list of the unique object identifiers for every object being processed by the current node.

ALLOBJNAMES

This string contains a space separated list of the names of every object being processed by the current node.

OBJCT

This value is the simulation time (see variable ST) at which the current object was created.

Therefore, to check if an object was created on the current timestep, the expression `\$ST == \$OBJCT` should always be used. This value will be zero if the node does not process objects sequentially (such as the Group DOP).

OBJCF

This value is the simulation frame (see variable SF) at which the current object was created.

This value is equivalent to using the dopsttoframe expression on the OBJCT variable. This value will be zero if the node does not process objects sequentially (such as the Group DOP).

OBJNAME

This is a string value containing the name of the object being processed.

Object names are not guaranteed to be unique within a simulation. However, if you name your objects carefully so that they are unique, the object name can be a much easier way to identify an object than the unique object identifier, OBJID.

The object name can also be used to treat a number of similar objects (with the same name) as a virtual group. If there are 20 objects named "myobject", specifying `strcmp(\$OBJNAME, "myobject") == 0` in the activation field of a DOP will cause that DOP to operate only on those 20 objects. This value will be the empty string if the node does not process objects sequentially (such as the Group DOP).

DOPNET

This is a string value containing the full path of the current DOP Network. This value is most useful in DOP subnet digital assets where you want to know the path to the DOP Network that contains the node.

## Examples

TypesOfDrag Example for Drag Force dynamics node

This sample illustrates three different ways to apply drag on an rbd object: by dragging the linear velocity, by dragging the angular velocity, or by directly changing the angular velocity.

The following examples include this node.

TypesOfDrag Example for Drag Force dynamics node

This sample illustrates three different ways to apply drag on an rbd object: by dragging the linear velocity, by dragging the angular velocity, or by directly changing the angular velocity.

SimpleField Example for Field Force dynamics node

This example demonstrates the use of the Field Force DOP. A group of RBD Objects are passed through a field which at first pulls the together, and then pulls them apart as they advance through the field.

VariableDrag Example for Fluid Object dynamics node

This example shows how to vary the drag in a fluid simulation. It provides examples of using a specified field to be a high drag zone, of automatically applying drag only to the fluid surface, and of applying negative drag to an area to make the fluid more volatile.

TurbulentSmoke Example for Wind Force dynamics node

This example illustrates how the Wind DOP can be used to add turbulence to a fluid simulation.

CrowdPov Example for Agent Cam object node

This example demonstrates how the agent cam can be assigned to a crowd agent to give you the point of view from someone in a crowd simulation.

AlphaOmega Example for Points from Volume geometry node

This example demonstrates how to use a Points From Volume SOP to create a target goal for a flip simulation and make it fill a given piece of geometry.

# Dynamics nodes

• Marks a simulation object as active or passive.

• Creates affector relationships between groups of objects.

• Blends between a set of animation clips based on the agent’s turn rate.

• Layers additional animation clips onto an agent.

• Chooses an object/position for the head of an agent to look at.

• Moves the head of an agent to look at a target.

• Adapts the legs of an agent to conform to terrain and prevent the feet from sliding.

• Adapts the legs of a biped agent to conform to terrain.

• Project the agent/particle points onto the terrain

• Defines an orientation that aligns an axis in object space with a second axis defined by the relative locations of two positional anchors.

• Defines multiple points, specified by their number or group, on the given geometry of a simulation object.

• Defines orientations based on multiple points on the given geometry of a simulation object.

• Defines a position by looking at the position of a point on the geometry of a simulation object.

• Defines an orientation by looking at a point on the geometry of a simulation object.

• Defines a position by looking at the position of a point on the geometry of a simulation object.

• Defines an orientation by looking at a point on the geometry of a simulation object.

• Defines a position by looking at the position of a particular UV coordinate location on a primitive.

• Defines a position by specifying a position in the space of some simulation object.

• Defines an orientation by specifying a rotation in the space of some simulation object.

• Defines multiple attachment points on a polygonal surface of an object.

• Defines a position by specifying a position in world space.

• Defines an orientation by specifying a rotation in world space.

• Attaches data to simulation objects or other data.

• Creates relationships between simulation objects.

• Attaches the appropriate data for Bullet Objects to an object.

• Sets and configures an Bullet Dynamics solver.

• Applies a uniform force to objects submerged in a fluid.

• Constrains a set of points on a cloth object to the surface of a Static Object.

• Attaches the appropriate data for Cloth Objects to an object.

• Defines the mass properties.

• Defines the physical material for a deformable surface.

• Defines the internal cloth forces.

• Creates a Cloth Object from SOP Geometry.

• Creates a Cloth Object from SOP Geometry.

• Defines the plasticity properties.

• Constrains part of the boundary of a cloth object to the boundary of another cloth object.

• Defines how cloth uses target.

• Defines a way of resolving collisions involving a cloth object and DOPs objects with volumetric representations (RBD Objects, ground planes, etc.)

• Constrains an object to remain a certain distance from the constraint, and limits the object’s rotation.

• Constrains pairs of RBD objects together according to a polygon network.

• Defines a set of constraints based on geometry.

• Visualizes the constraints defined by constraint network geometry.

• Creates multiple copies of the input data.

• Sets and configures a Copy Data Solver.

• Mimics the information set by the Copy Object DOP.

• Defines a Crowd Fuzzy Logic

• Creates a crowd object with required agent attributes to be used in the crowd simulation.

• Updates agents according to their steer forces and animation clips.

• Update crowd agents based on the custom steerforces and adjusting animation playback of clips

• Defines a Crowd State

• Defines a Crowd State.

• Defines a transition between crowd states.

• Defines a transition between crowd states.

• Defines a Crowd Trigger

• Defines a Crowd Trigger

• Combines multiple crowd triggers to build a more complex trigger.

• Adds a data only once to an object, regardless of number of wires.

• Deletes both objects and data according to patterns.

• Applies force and torque to objects that resists their current direction of motion.

• Defines how the surrounding medium affects a soft body object.

• Controls Embedded Geometry that can be deformed along with the simulated geometry in a finite element simulation.

• Creates an Empty Data for holding custom information.

• Creates an Empty Object.

• Constrains points of a solid object or a hybrid object to points of another DOP object.

• Creates an FEM Hybrid Object from SOP Geometry.

• Constrains regions of a solid object or a hybrid object to another solid or hybrid object.

• Creates a simulated FEM solid from geometry.

• Sets and configures a Finite Element solver.

• Constrains an FEM object to a target trajectory using a hard constraint or soft constraint.

• Attaches the appropriate data for Particle Fluid Objects to become a FLIP based fluid.

• Evolves an object as a FLIP fluid object.

• Applies forces on the objects as if a cone-shaped fan were acting on them.

• Fetches a piece of data from a simulation object.

• Applies forces to an object using some piece of geometry as a vector field.

• Creates a vortex filament object from SOP Geometry.

• Evolves vortex filament geometry over time.

• Imports vortex filaments from a SOP network.

• Saves and loads simulation objects to external files.

• Allows a finite-element object to generate optional output attributes.

• Attaches the appropriate data for Fluid Objects to an object.

• Applies forces to resist the current motion of soft body objects relative to a fluid.

• Attaches the appropriate data for Fluid Objects to an object.

• A solver for Sign Distance Field (SDF) liquid simulations.

• A microsolver that adjusts an internal coordinate system attached to fluid particles in a particle fluid simulation.

• A microsolver that adjusts the strength of elastic bonds between pairs of particles in a fluid simulation.

• A microsolver that advects fields and geometry by a velocity field.

• A microsolver that advects fields and geometry by a velocity field using OpenCL acceleration.

• A microsolver that advects fields and geometry by a velocity field.

• A microsolver that computes analytic property of fields.

• A microsolver that swaps geometry attributes.

• A microsolver that blends the density of two fields.

• A microsolver that blurs fields.

• A microsolver that determines the collision field between the fluid field and any affector objects.

• A microsolver that builds a mask for each voxel to show the presence or absence of relationships between objects.

• A microsolver that calculates an adhoc buoyancy force and updates a velocity field.

• Sets the object to use the Gas Burn solver.

• Creates an object with appropriate data to use as a fire source.

• A microsolver that performs general calculations on a pair of fields.

• A microsolver that detects collisions between particles and geometry.

• A microsolver that applies a combustion model to the simulation.

• A microsolver that calculates particle fluid attribute values for each particle in a particle fluid field.

• A microsolver that adjusts an SDF according to surface markers.

• A microsolver that computes the cross product of two vector fields.

• A DOP node that creates forces generated from a curve.

• A microsolver that applies one round detontation shock dyanamics.

• Attaches the appropriate data for Smoke Objects to become a flame front based fire.

• A microsolver that applies the flamefront-based fire simulation.

• A microsolver that scales down velocity, damping motion.

• A microsolver that diffuses a field or point attribute.

• A microsolver that dissipates a field.

• Adds detail at a certain scale by applying "disturbance" forces to a scalar or vector field.

• Adds detail at a certain scale by applying "disturbance" forces to a scalar or vector field.

• A microsolver that runs once for each matching data.

• A microsolver that computes pairwise elastic forces between particles in a fluid simulation.

• A microsolver that embeds one fluid inside another.

• A microsolver that enforces boundary conditions on a field.

• A microsolver that equalizes the density of two fields.

• A microsolver that equalizes the volume of two fields.

• A microsolver that evaluates the external DOPs forces for each point in a velocity field and updates the velocity field accordingly.

• A microsolver that extrapolates a field’s value along an SDF.

• A microsolver that creates a feathered mask out of a field.

• A microsolver that calculates and applies feedback forces to collision geometry.

• A data node that fetches the fields needed to embed one fluid in another.

• Runs CVEX on a set of fields.

• Runs CVEX on a set of fields.

• A microsolver that copies the values of a field into a point attribute on geometry.

• A microsolver that defragments geometry.

• A microsolver that creates a signed distance field out of geometry.

• Blends a set of SOP volumes into a set of new collision fields for the creation of a guided simulation.

• A microsolver that copies Impact data onto point attributes.

• A microsolver that applies forces to a particle fluid system.

• A microsolver that solves its subsolvers at a regular interval.

• A microsolver that clamps a field within certain values.

• A microsolver that keeps particles within a box.

• A microsolver that combines multiple fields or attributes together.

• A microsolver that adaptively sharpens a field.

• A microsolver that looksup field values according to a position field.

• A microsolver that rebuilds fields to match in size and resolution to a reference field.

• A microsolver that arbitrary simulation data between multiple machines.

• A microsolver that exchanges boundary data between multiple machines.

• A microsolver that exchanges boundary data between multiple machines.

• A microsolver that balances slices data between multiple machines.

• A microsolver that exchanges boundary data between multiple machines.

• Executes the provided kernel with the given paramters

• A microsolver that counts the number of particles in each voxel of a field.

• A microsolver that computes pairwise collision forces between particles that represent instanced spheres.

• A microsolver that moves particles to lie along a certain isosurface of an SDF.

• Updates a neighbourhood list for Geometry to match moved points.

• A microsolver that computes pairwise fluid pressure forces between particles in a fluid simulation.

• A microsolver that separates adjacent particles by adjusting their point positions..

• A microsolver that copies a particle system’s point attribute into a field.

• A microsolver that converts a particle system into a signed distance field.

• A microsolver that removes the divergent components of a velocity field.

• A microsolver that removes the divergent components of a velocity field using a multi-grid method.

• A microsolver that removes the divergent components of a velocity field.

• A microsolver that reduces a field to a single constant field .

• A microsolver that reduces surrounding voxels to a single value.

• A microsolver that reinitializes a signed distance field while preserving the zero isocontour.

• A microsolver that repeatedly solves its input.

• A microsolver that changes the size of fields.

• A microsolver that resizes a fluid to match simulating fluid bounds

• A microsolver that initializes a rest field.

• A microsolver that converts an SDF field to a Fog field.

• A microsolver that calculates the density at particle positions in a particle field using techniques from Smoothed Particle Hydrodynamics.

• A microsolver that uses techniques from Smoothed Particle Hydrodynamics to compute pressure, viscosity and surface tension forces acting between particles in a fluid simulation.

• A microsolver that computes the forces to treat the fluid simulation as sand rather than fluid.

• A microsolver that seeds marker particles around the boundary of a surface.

• A microsolver that seeds particles uniformly inside a surface.

• Applies a Shredding Force to the velocity field specified.

• A microsolver that computes slice numbers into an index field.

• Adjusts a fluid velocity field to match collision velocities.

• A microsolver that calculates the forces imparted by a strain field.

• A microsolver that updates the strain field according to the current velocity field.

• A microsolver that substeps input microsolvers.

• A microsolver that snaps a surface onto a collision surface.

• A microsolver that calculates a surface tension force proportional to the curvature of the surface field.

• A microsolver that applies a force towards a target object.

• Modifies the temperature of a FLIP over time.

• Applies Turbulence to the specified velocity field.

• Up-scales and/or modifies a smoke, fire, or liquid simulations.

• A microsolver that reorients geometry according to motion of a velocity field.

• A microsolver that applies viscosity to a velocity field.

• A microsolver that seeds flip particles into a new volume region.

• Remaps a field according to a ramp.

• Applies a confinement force on specific bands of sampled energy.

• Applies a vortex confinement force to a velocity field.

• Applies a confinement force on specific bands of sampled energy.

• A microsolver that applies forces to a velocity field or geometry according to vorticle geometry.

• A DOP node that adds the appropriately formatted data to represent vorticles.

• A DOP node that recycles vorticles by moving them to the opposite side of the fluid box when they leave.

• A microsolver that performs a wavelet decomposition of a field.

• A microsolver that applies a wind force.

• Runs CVEX on geometry attributes.

• Runs a VEX snippet to modify attribute values.

• Applies a gravity-like force to objects.

• Creates a ground plane suitable for RBD or cloth simulations.

• Creates simulation object groups.

• Defines a constraint relationship that must always be satisfied.

• Attaches the appropriate data for Hybrid Objects to an object.

• Stores filtered information about impacts on an RBD object.

• Applies an impulse to an object.

• Creates an index field.

• Visualizes an index field.

• Creates DOP Objects according to instance attributes

• Marks a simulation object as intangible or tangible.

• Stores the name of the scene level object source for this DOP object.

• Apply forces on objects using a force field defined by metaballs.

• Creates a matrix field.

• Visualizes a matrix field.

• Merges multiple streams of objects or data into a single stream.

• Modifies or creates options on arbitrary data.

• Defines an object’s position, orientation, linear velocity, and angular velocity.

• Unified visualization of multiple fields.

• A DOP that transfers arbitrary simulation data between multiple machines.

• Does nothing.

• Creates position information from an object’s transform.

• Serves as the end-point of the simulation network. Has controls for writing out sim files.

• Uses vortex filaments to move particles.

• A POP node that uses velocity volumes to move particles.

• A POP node that attracts particles to positions and geometry.

• A POP node that copies volume values into a particle attribute.

• A POP node that resets the stopped attribute on particles, waking them up.

• A POP node that applies a force around an axis.

• A POP node that reacts to collisions.

• A POP node that detects and reacts to collisions.

• A POP node marks particles to ignore implicit collisions.

• A POP node that colors particles.

• A POP node that creates forces generated from a curve.

• A POP node that applies drag to particles.

• A POP node that applies drag to the spin of particles.

• A POP node that applies a conical fan wind to particles.

• A POP node that creates a simple fireworks system.

• A POP node that floats particles on the surface of a liquid simulation.

• A POP node that applies a flocking algorithm to particles.

• Controls local density by applying forces between nearby particles.

• A POP node that applies forces to particles.

• A POP node that applies sand grain interaction to particles.

• A POP node that groups particles.

• A POP node that sets up the instancepath for particles.

• A POP node that applies forces between particles.

• A POP node that kills particles.

• A POP node that limits particles.

• A POP node that applies forces within the particle’s frame.

• A POP solver that generates particles at a point.

• A POP node makes a particle look at a point.

• A POP node that applies forces according to metaballs.

• Converts a regular particle system into a dynamic object capable of interacting correctly with other objects in the DOP environment.

• A POP node that sets various common attributes on particles.

• A POP node that sets attributes based on nearby particles.

• A POP Node that generates particles from incoming particles.

• A POP node that creates a spongy boundary.

• A POP solver updates particles according to their velocities and forces.

• A POP node that generates particles from geometry.

• A POP node that sets the speed limits for particles.

• A POP node that sets the spin of particles..

• A POP node that uses the vorticity of velocity volumes to spin particles.

• A POP node that sets the sprite display for particles.

• Applies force to agents/particles to align them with neighbors.

• Applies anticipatory avoidance force to agents/particles to avoid potential future collisions with other agents/particles.

• Applies forces to agents/particles to bring them closer to their neighbors.

• Applies forces to agents/particles calulated using a VOP network.

• Applies force to agents/particles to avoid potential collisions with static objects.

• Applies force to agents/particles to avoid potential collisions with static objects.

• Applies force to agents/particles according to directions from a path curve.

• Applies force to agents/particles to move them toward a target position.

• Apply force to agents/particles to move them apart from each other.

• Used internally in the crowd solver to integrate steering forces.

• Used internally in the crowd solver to integrate custom steering forces.

• Constrains agent velocity to only go in a direction within a certain angle range of its current heading, to prevent agents from floating backward.

• Apply forces to agents/particles to create a random motion.

• A POP node that creates a new stream of particles.

• A POP node that applies torque to particles, causing them to spin.

• Runs CVEX on a particle system.

• A POP node that directly changes the velocity of particles.

• A POP node that applies wind to particles.

• Runs a VEX snippet to modify particles.

• Attaches the appropriate data for Particle Fluid Objects to an object.

• Emits particles into a particle fluid simulation.

• Creates a Particle Fluid Object from SOP Geometry.

• Evolves an object as a particle fluid object.

• Visualizes particles.

• Creates simulation object groups based on an expression.

• Defines the base physical parameters of DOP objects.

• Applies a force to an object from a particular location in space.

• Creates position information from a point on some SOP geometry.

• Associates a position and orientation to an object.

• Sets and configures a Pyro solver. This solver can be used to create both fire and smoke.

• Constrains an RBD object to a certain orientation.

• Constrains an RBD object to have a certain orientation, but with a set amount of springiness.

• Automatically freezes RBD Objects that have come to rest

• Attaches the appropriate data for RBD Objects to an object.

• Creates a number of RBD Objects from SOP Geometry. These individual RBD Objects are created from the geometry name attributes.

• Constrains an object to two constraints, creating a rotation similar to a hinge or a trapeze bar.

• Creates an RBD Object from SOP Geometry.

• Creates a single DOP object from SOP Geometry that represents a number of RBD Objects.

• Constrains an RBD object a certain distance from the constraint.

• Creates a simulation object at each point of some source geometry, similarly to how the Copy surface node copies geometry onto points.

• Sets and configures a Rigid Body Dynamics solver.

• Constrains an object to remain a certain distance from the constraint, with a set amount of springiness.

• Alters the state information for an RBD Object.

• Saves the state of a DOP network simulation into files.

• Applies forces to an object according to the difference between two reference frames.

• Sets and configures a Rigid Body Dynamics solver.

• Attaches the appropriate data for Ripple Objects to an object.

• Creates an object from existing geometry that will be deformed with the ripple solver.

• Animates wave propagation across Ripple Objects.

• Creates a signed distance field representation of a piece of geometry that can be used for collision detection.

• A microsolver that performs general calculations on a pair consisting of a DOP field and a SOP volume/VDB.

• Creates a scalar field from a SOP Volume.

• Creates a vector field from a SOP Volume Primitive.

• Creates a scalar field.

• Visualizes a scalar field.

• Defines the internal seam angle.

• Defines the mass density of a Cloth Object.

• Divides a particle system uniformly into multiple slices along a line.

• Specifies a cutting plane to divide a particle system into two slices for distributed simulations.

• Constrains an object to rotate and translate on a single axis, and limits the rotation and translation on that axis.

• Attaches the appropriate data for Smoke Objects to an object.

• Creates an Smoke Object from SOP Geometry.

• Sets and configures a Smoke solver. This is a slightly lower-level solver that is the basis for the Pyro solver.

• Constrains a set of points on a soft body object to a certain position using a hard constraint or soft constraint.

• Constrains a point on a soft body object to a certain position.

• Constrains a point on a soft body to a certain position, with a set amount of springiness.

• Defines how a soft body object responds to collisions.

• Defines how a Soft Body Object responds to collisions.

• Defines how a Soft Body Object responds to collisions.

• Defines how a Soft Body Object responds to collisions.

• Allows the user to import the rest state from a SOP node.

• Sets and configures a Soft Body solver.

• Defines the strengths of the soft constraint on a soft body object.

• Controls the anisotropic behavior of a Solid Object.

• Attaches the appropriate data for Solid Objects to an object.

• Defines the mass density of a Solid Object.

• Defines how a Solid Object reacts to strain and change of volume.

• Creates a Solid Object from SOP Geometry.

• This builds a tree of spheres producing bounding information for an edge cloud.

• This builds a tree of spheres producing bounding information for a point cloud.

• Splits an incoming object stream into as many as four output streams.

• Creates a Static Object from SOP Geometry.

• Allows you to inspect the behavior of a static object in the viewport.

• Control the thickness of the object that collides with cloth.

• Passes one of the input object or data streams to the output.

• Creates a Terrain Object from SOP Geometry.

• Defines a way of resolving collisions between two rigid bodies.

• Applies a uniform force and torque to objects.

• Applies forces on the objects according to a VOP network.

• Creates a vector field.

• Visualizes a vector field.

• Modifies common Vellum Constraint properties during a Vellum solve.

• Microsolver to create Vellum constraints during a simulation.

• Creates a DOP Object for use with the Vellum Solver.

• Blends the current rest values of constraints with a rest state calculated from the current simulation or external geometry.

• Sets and configures a Vellum solver.

• A Vellum node that creates Vellum patches.

• Applies an impulse to an object.

• A microsolver to create soft references to visualizers on itself.

• Imports SOP source geometry into smoke, pyro, and FLIP simulations.

• Defines a way of resolving collisions involving two rigid bodies with volume.

• Attaches the appropriate data to make an object fractureable by the Voronoi Fracture Solver

• Defines the parameters for dynamic fracturing using the Voronoi Fracture Solver

• Dynamically fractures objects based on data from the Voronoi Fracture Configure Object DOP

• Applies a vortex-like force on objects, causing them to orbit about an axis along a circular path.

• Creates a Whitewater Object that holds data for a whitewater simulation.

• Creates a Whitewater Object that holds data for a whitewater simulation.

• Sets and configures a Whitewater Solver.

• Sets and configures a Whitewater solver.

• Applies forces to resist the current motion of objects relative to a turbulent wind.

• Constrains a wire point’s orientation to a certain direction.

• Constrains a wire point’s orientation to a certain direction, with a set amount of springiness.

• Attaches the appropriate data for Wire Objects to an object.

• Defines the elasticity of a wire object.

• Constraints a wire point to a certain position and direction.

• Creates a Wire Object from SOP Geometry.

• Defines the physical parameters of a wire object.

• Defines the plasticity of a wire object.

• Sets and configures a Wire solver.

• Defines a way of resolving collisions involving a wire object and DOPs objects with volumetric representations.

• Defines a way of resolving collisions between two wires.