Houdini 20.5 Shelf tools

Beach Tank shelf tool

Creates a FLIP fluid simulation of a beach with continuous waves.

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Overview

This tool creates a FLIP tank simulation of waves breaking on a beach or other shallow water terrain. This tool is similar to the Wave Tank, except it enables an option to ramp down ocean velocities in a certain direction across the length of the tank. Reducing the velocities allow the ocean waves to break naturally as the water get shallower. The FLIP Simulation uses a POP Advect By Volumes node to continuously add the ramped wave velocities to the simulation.

Similar to the Wave Tank, this tool creates a boundary layer of particles to suppress reflections at the edge of the tank, contribute ocean velocities back to the simulation, and maintain the water volume level to match the ocean. The boundary layer will by default be disabled along the maximum extent of the volume in the specified direction.

The Ocean Spectrum node allows you to shape the initial frame of your simulated ocean, and Ocean Source controls the outputs.

Tip

For more information, see the differences between ocean tank types help page.

Using Beach Tank

  1. Click the Beach Tank tool on the Oceans tab to create a tank.

  2. Select a polygonal object to be extruded and act as the main beach collision object. If you don’t choose an object, a default one will be created for you.

Changing the look of your ocean

To...Do this

Set the height of the wave

Navigate to the Ocean Spectrum node and adjust the Wave Scale parameter on the Wave Amplitude tab.

This value is multiplied by the Speed parameter on the Wind tab.

Set the direction of the waves

Navigate to the Ocean Spectrum node and adjust the Directional Bias parameter on the Wind tab.

This controls how many frequencies are moving in the same direction as the wind. Increasing this value will cause more frequencies to travel in the same direction, which is useful for creating shoreline effects.

You can also try increasing the Directional Movement parameter. This will dampen the waves moving in the opposite direction of the wind, leaving only the ones moving in the same direction.

Control the height of the peak

Navigate to the Ocean Spectrum node and adjust the Chop parameter on the Wind tab.

Increasing this parameter creates sharp peaks on waves. However, if this value is too high waves, may invert on themselves.

Add more detail to your ocean

Increase the Resolution Exponent parameter on the Ocean Spectrum node.

Note

The Resolution Exponent parameter will not only determine the quality of your ocean, but also the size of the texture maps that you will eventually write out.

Create a large ocean

Use the Large Ocean shelf tool.

Understanding the network of nodes

There are three important layers to focus on when creating your ocean. First create the ocean, next add whitewater, and finally add specularity for the whitewater.

Tip

Disable all whitewater nodes at the OBJ level while you work on your ocean, then disable the ocean nodes while you work on your whitewater.

The first set of nodes control the ocean itself.

  1. fluidtank_initial controls the first frame of your simulation. This is where you can shape the initial frame of your tank with Ocean Spectrum and control the outputs with Ocean Source. This includes the size of your tank, the depth of the water etc.

  2. AutoDopNetwork controls the simulation of your tank. This is where you will find the FLIP Object and FLIP Solver. The FLIP simulation will contain Volume Source DOPs to sink and source the boundary layer particles, and a Gas Guiding Volume DOP to add ocean velocities to the simulation. Note, the Beach Tank shelf tool uses POP Advect By Volumes to inject ocean velocities.

  3. fluidtank_fluid is the result of #1 and #2 combined, and is where the results are rendered. After the simulation is done, this node collects the fluid particles, sets up a material, creates some nodes for surfacing to finish the effect.

  4. fluidtank_interior is also used for rendering, and for creating the volumetric effect that one of the shaders applies to the interior of the fluid. It controls the volume beneath the surface, such as how cloudy or murky the water will appear.

The next set of nodes are to control the whitewater.

Note

To add whitewater to your simulation, use the Whitewater tool on the Oceans shelf.

  1. whitewater_source is where the spray and foam is coming from.

  2. whitewater_sim is where the whitewater simulated. This is where you can modify the animation.

  3. import_whitewater is the result of #1 and #2 combined.

For more information see How to animate a wave tank with whitewater.

Note

If you build a completely procedural ocean (using the the Large Ocean or Small Ocean shelf tools for example), the Ocean Foam SOP is used.

Tips for improving the look of your water

  • The defaults for the tank will create a low res simulation, which makes it easy to animate. However, to create a nice looking render, you will need to change some of the defaults. For example, you will need to increase the number of particles in your scene. Decreasing the Particle Separation parameter to about 0.03 will create a simulation with approximately 30 million particles.

  • Add an environment light to your scene. Water reflects and refracts a lot of the environment around it, so having an environment map in your scene will significantly improve the look.

    Tip

    In your Environment Map parameter, navigate to the HFS/houdini/pic/ folder and choose the sky file DOSCH_SKIESV2_${F2}SN_lowres.rat.

See also

Shelf tools

Using the shelf

  • Customize the shelf

    How to change the look of the shelf, change and rearrange its contents, and create your own shelf tools.

Technical