Houdini 17.0 Nodes Dynamics nodes

Whitewater Object dynamics node

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

The Whitewater Object DOP creates a Whitewater Object inside the DOP simulation. It creates a new object and attaches the subdata required for the Whitewater Solver to operate.

Parameters

Creation

Creation Frame Specifies Simulation Frame

Determines if the creation frame refers to global Houdini frames ($F) or to simulation specific frames ($SF). The latter is affected by the offset time and scale time at the DOP network level.

Creation Frame

The frame number on which the object will be created. The object is created only when the current frame number is equal to this parameter value. This means the DOP Network must evaluate a timestep at the specified frame, or the object will not be created.

For example, if this value is set to 3.5, the Timestep parameter of the DOP Network must be changed to 1/(2*$FPS) to ensure the DOP Network has a timestep at frame 3.5.

Object Name

The name for the created object. This is the name that shows up in the details view and is used to reference this particular object externally.

Note

While it is possible to have many objects with the same name, this complicates writing references, so it is recommended to use something like $OBJID in the name.

Solve On Creation Frame

For the newly created objects, this parameter controls whether or not the solver for that object should solve for the object on the timestep in which it was created.

Usually this parameter will be turned on if this node is creating objects in the middle of a simulation rather than creating objects for the initial state of the simulation.

Allow Caching

By preventing a large object from being cached, you can ensure there is enough room in the cache for the previous frames of its collision geometry.

This option should only be set when you are working with a very large sim. It is much better just to use a larger memory cache if possible.

Physical

Bounce

The elasticity of the object. If two objects of bounce 1.0 collide, they will rebound without losing energy. If two objects of bounce 0.0 collide, they will come to a standstill.

Bounce Forward

The tangential elasticity of the object. If two objects of bounce forward 1.0 collide, their tangential motion will be affected only by friction. If two objects of bounce forward 0.0 collide, their tangential motion will be matched.

Friction

The coefficient of friction of the object. A value of 0 means the object is frictionless.

This governs how much the tangential velocity is affected by collisions and resting contacts.

Dynamic Friction Scale

An object sliding may have a lower friction coefficient than an object at rest. This is the scale factor that relates the two. It is not a friction coefficient, but a scale between zero and one.

A value of one means that dynamic friction is equal to static friction. A scale of zero means that as soon as static friction is overcome the object acts without friction.

Guides

Particles

Color Particles by Depth

When enabled, whitewater particles will be colored by depth. The actual color is determined from Visualization Range and Color Ramp.

Visualization Range

Horizontal axis of the Color Ramp corresponds to this depth range.

Repellants

Repellants

Enabling this option will render the repellants as spheres of the given size and color.

Visualize Attribute

When enabled, repellant colors are derived from the value of this point attribute.

Note

See documentation for the Whitewater Solver for a list of repellant attributes.

Visualization Mode

Specifies the color spectrum used for visualizing repellant attributes. When mode is set to Ramp, the custom Color Ramp is used.

Detect Range

When enabled, the range of values for the visualization attribute will be automatically calculated; if this option is disabled, the provided Visualization Range is used instead.

Visualization Range

When Detect Range is disabled, the visualization attribute is colored based on its value relative to this range.

Fields

The surface and velocity fields sourced from the input fluid simulation can be visualized in a number of ways. The help for Scalar Field Visualization and Vector Field Visualization provides more details about how these work.

Note

Field visualization will only work if Import Volumes is enabled on the Whitewater Solver.

See also

Dynamics nodes