Houdini 20.5 Nodes Geometry nodes

Ocean Evaluate geometry node

Deforms input geometry based on ocean “spectrum” volumes.

Since 12.5

This node uses volumes generated by the Ocean Spectrum node connected to the second input to deform geometry in the first input.

Parameters

Time

The time at which to evaluate the ocean surface.

Downsample

Downsample the incoming ocean spectrum before evaluating any ocean values. This parameter specifies the number of powers of two to remove from the resolution of the incoming ocean spectrum. For example, if the spectrum was originally specified at resolution 10 to generate a 1024 x 1024 volume, downsampling by 2 will evaluate ocean volumes at resolution 8, a 256 x 256 volume.

Tip

The same high resolution spectrum can be processed by multiple Ocean Evaluate nodes, for example one with no downsampling to deform surface geometry, and another at a downsampled resolution to generate the more expensive volume or point output.

Depth Falloff

Specifies how deformation and velocity values falloff as the input points lie below the ocean surface. This value also controls the rank of the calculation volumes that are output if Rest Displacement or Rest Velocity is enabled: 2D if falloff is None but 3D otherwise.

None

Values do not falloff below the surface.

Exponential

All values have the same exponential falloff below the surface.

Exponential by Frequency

Values have an exponential falloff that is scaled per wave frequency. With this setting the contribution from small, high frequency waves falls off very quickly. It is the most accurate setting and most expensive to compute.

Falloff Scale

An additional scale applied to the exponential falloff modes in Depth Falloff. For the most physically accurate values this should be set to 1 in conjunction with the Exponential by Frequency mode.

Max Depth

The maximum depth for the evaluated ocean volumes. All input positions deeper than this value will be clamped before sampling the ocean values.

Depth Divisions

The number of divisions along the depth axis if the computed ocean are 3D, as specified by the Depth Falloff parameter. Higher values are more accurate but more expensive to calculate.

Geometry

Deform Input Geometry

Deform the input geometry by the calculated ocean deformations.

Preview Grid

Output a deformed grid exactly the size of the underlying ocean volume. This preview grid is fastest to evaluate and provides a simple way to view the deforming ocean surface.

Point Velocity

Add a velocity point attribute to the output geometry.

UV Attribute

Add a uv attribute to the output geometry that can be used for texture lookups into the texture maps created with the Export to Texture tab..

Cusp Attribute

Add a cusp point attribute to the output geometry that represents the sharpness of the wave peaks at any point, with values ranging from below 0 if the wave is stretched out, to greater than 1 if the wave peak is so sharp it has inverted.

Cusp Direction Attribute

Add a cuspdir vector point attribute to the output geometry that points in the direction of the wave peaks.

Foam Attribute

Add a foam point attribute to the output geometry that holds the results of a simple simulation of the cusp attribute decaying over time. The parameters for the simulation can be found on the Foam Solver tab.

Visualize Attribute

Visualize the cusp or foam attribute by color.

Attribute Ramp

The color ramp with which to visualize the cusp or foam attribute.

Volumes

Surface SDF

Generate a surface SDF volume of the specified size and resolution.

Surface Depth

The Surface SDF will represent the ocean at the specified depth. This differs from simply offsetting the output surface SDF as it takes into account the Depth Falloff setting.

Velocity

Generate a vel velocity volume of the specified size and resolution.

Smoothing

Controls the radius of the points used to generate volumes. Higher values are more expensive but give smoother volumes.

Size

The size of the generated volumes.

Center

The origin of the generated volumes.

Uniform Sampling

It is often advantageous to make sure voxels in a volume are cubes. This option allows the resolution of the volume to be specified without having to worry about matching the size and resolution fields. This parameter controls which axis is divided into Uniform Sampling Divisions.

Uniform Sampling Divs

The number of voxels to divide the Uniform Sampling axis into. The other axes will be divided into the number of cells that fit for this voxel size.

Sampling Divs

When using non-uniform voxel cells, each dimensions resolution can be specified here.

Div Size

The uniform size of the voxels, when specifying the voxel size directly. The given sized box will be filled by voxels of this size.

Max Extrap Cells

When generating velocity volumes, how many voxels from the ocean surface to extrapolate velocity values.

Rest Volumes

Rest Displacement

Output the internally computed displacement volume. Samples taken from this volume should be in rest position.

Rest Velocity

Output the internally computed velocity volume. Samples taken from this volume should be in rest position.

Rest Cusp

Output the internally computed cusp volume. Samples taken from this volume should be in rest position.

Rest Cusp Direction

Output the internally computed cusp direction volume. Samples taken from this volume should be in rest position.

Foam Solver

Rest Foam

Output the internally computed foam volume. Samples taken from this volume should be in rest position. The Ocean Shader uses this volume as a Foam Mask after being saved to a texture on the Export to a Texture tab.

Reset Simulation

Reset the state of the foam simulation, which may be necessary after changing the resolution of the ocean grid or the Downsample parameter.

Start Frame

The starting frame for the foam simulation. Setting this to a frame earlier than the first frame allows a pre-roll of the simulation.

Cusp Scale

Scale the incoming cusp attribute by this factor before accumulating foam.

Decay

The amount of foam to decay each frame.

Min Velocity

The minimum velocity for waves that can accumulate foam.

Max Velocity

The maximum velocity for waves that can accumulate foam.

Min Cusp

The minimum cusp value that can accumulate to foam.

Max Cusp

The maximum cusp value that can accumulate to foam.

Points

Points from Volume

Generate points with velocity in the volumetric intersection of the ocean surface and the specified box.

Point Separation

The smallest distance between any two of the generated points in the initial configuration.

Jitter Seed

Random seed for creating jitter.

Jitter Scale

The amount of jitter to apply to the positional values of the points.

Min Rest Depth

The minimum depth of points relative to the ocean surface.

Max Rest Depth

The maximum depth of points relative to the ocean surface.

Box Size

The size of the box in which to generate points.

Box Center

The origin of the box in which to generate points.

Pad Scale

The rest configuration of points is generated by evaluating the maximum possible ocean displacement at time zero. This will usually be sufficient padding, but with extreme displacement it might be necessary to increase the padding scale in this parameter.

Create Output Group

Create a group containing the generated points.

Output Group

The name of the generated output point group.

Export to Texture

This tab controls exporting the displacement and cusp volumes to textures that can be sampled during rendering. Most of the parameters here are exposed from the Composite output node.

Channels

Controls where the displacement, cusp, and / or foam values are stored in the texture.

Raster Depth

Controls the bit depth of the generated textures. If the texture format supports 16-bit float, this bit depth can save space with little degradation in rendering.

See also

Geometry nodes