Render a Bifröst simulation

Note: Make sure to turn off Run up to current time in your Dynamics preferences when rendering.

Use the Bifröst materials for mental ray

When you create Bifröst simulations, special mental ray shaders are automatically applied as materials. These shaders allow you to use the channels that are defined on the Bifröst object to drive the weight and color of various shading components. For example, you can use the vorticity and velocity channels to drive the weight and color of the Surface Foam layer to simulate churning whitewater in a liquid simulation.

1. Select an option from one of the Remap Channel controls. Different channels are available, depending on the type of simulation.
2. Expand the associated Remap block to define a ramp based on the values from the Bifröst object.
   Tip: You can preview the channel values in Viewport 2.0 to get an idea of the ranges to use for remapping. See Display Bifröst diagnostic information.

Use custom shading networks

When using the Hypershade or Node Editor to create custom mental ray shading networks, you can use Bifröst channel shaders such bifrost_scalar_channel to return values from the Bifröst object and use them to drive the inputs of other shaders. For example, you can combine the vorticity and the length of the velocity to drive the transparency.

Render liquid and aero isosurface or mesh

The bifrostLiquidMaterial and bifrostAeroMaterial shaders can be used either to render the voxels directly, or to render the generated mesh. To avoid rendering both, you should hide the shape when generating a mesh.

Render the voxels' isosurface

If you did not generate a mesh, then the isosurface of the Bifröst liquid is rendered instead.

1. If the camera is inside the shape's bounding volume, make sure that Auto Volume is on in the Features group of the Configuration tab of the mental ray Render Settings.
2. Launch a render.

Note: You may receive messages about the Bifröst mesh shape having no faces. You can safely ignore these.

Render the mesh

1. Generate a mesh. See Work with Bifröst meshes.
2. Hide the bifrost shape object.
3. To render the mesh using the color sets stored on the mesh as the velocity and vorticity channels to drive the color remapping, make sure to turn on Use Vertex Colors in the Translation group on the Configuration tab of the mental ray Render Settings window. You must do this if you are using any of the color remapping options in the bifrostLiquidMaterial shader and the bifrost object is not present in the scene, for example, if you exported the mesh.

   If Use Vertex Colors is off, then the color remapping uses the velocity and vorticity channels sampled from the voxels.

4. Launch a render.

Render motion blur

For motion blur, you must set Motion Blur to Full in the Shutter group on the Quality tab of the mental ray Render Settings window. In addition, for liquid and aero simulations, you must render the mesh instead of rendering the voxels directly.

Render passes and layer overrides

When rendering passes and layers with overrides, you should render the mesh instead of the voxels.