Add and edit BOSS influences

Influences are the objects used to generate and reflect waves in the Bifröst Ocean Simulation System. They can be used to create effects like ripples, bow waves, and Kelvin wakes.

In addition to static and animated meshes, you can use an EXR file. For example, you can use a single EXR image instead of geometry for a complex shoreline with rocks. For another example, you can use a sequence of EXR images to create a pattern of rain falling on a surface of water.

Each influence can act as a generator that creates waves, as a collider that reflects waves, or as both. When an influence is both a generator and a collider, the region that acts as a collider should be a bit smaller than the region that acts as a generator so that waves can form properly in the band between them — you can adjust the Generator Expand and Collider Shrink attributes to adjust the width of this band.

Tip: Use hidden meshes as extra influences for more control over different parts of the effect. For example, you can use a simple mesh at the back of a boat to increase the wake.

To add a geometry influence

1. In the Wave Solver list on the left side of the Boss Ripple / Wave Generator window, select the solver to which you want to add an influence.
2. In the scene, select one or more polygon meshes to act as influences.
3. In the Boss Ripple / Wave Solver window, click .

   A BossGeoProperties node is created for each selected mesh.

To add an EXR image influence

1. Use an image editing application to create an image or sequence of images in EXR format. For best results, follow these guidelines:
   • The image will be stretched to fit the simulated region in the scene's world X and Z axes, so the image aspect ratio should match the aspect ratio of the base mesh (for wave solvers) and the patch size (for spectral solvers).
   • Use the R channel to define a mask for wave generation, where 1.0 represents the interior of the generator and 0.0 represents the background. Keep the outlines fairly crisp.
   • Use the G channel to define a mask for wave collision in the same way.
2. On the left side of the Boss Ripple / Wave Generator window, select the solver to which you want to add an influence.
3. In the Boss Ripple / Wave Solver window, click .
4. In the Attribute Editor, set EXR Filename to the file path and name of the image or sequence.

To edit an influence

To display an influence's attributes in the Attribute Editor:

1. Make sure that Auto Select Nodes is on in the Boss Ripple / Wave Generator window.
2. Select the associated solver in the Wave Solver list on the left.
3. Select the desired influence in the Wave Influences list to the right.

For a brief description of an attribute, hover the pointer over it. If a tooltip does not appear after a brief delay, make sure that Display Toolclips is on in your Help preferences.

Here are some notes on a few of the settings:

• Adjust Amplitude to control the relative strength of waves generated by different influences.

• Use Collider Offset X and Collider Offset Z to shift the collision region and change the shape of the wave generation band around it. For example, if you offset the collider towards the back of a boat, then the generation region at the front becomes larger and will create more prominent bow waves. Note that these attributes are relative to the scene's world axes, so if a boat is turning then you should animate them to match the boat's direction.

• The Resolution X and Resolution Y attributes of a geometry influence control the resolution at which the geometry is sampled, and are independent of the resolution of the solver and other influences.

As an alternative to the Attribute Editor, you can toggle the Generator and Collider checkboxes directly from the Boss Ripple / Wave Generator window:

• Click the blue G icon to turn Generator off. Click the gray G icon to turn it back on.
• Click the blue C icon to turn Collider off. Click the gray C icon to turn it back on.