Bifrost Compute and Cache Options

To display the Bifrost Compute and Cache Options window, choose Bifrost Fluids > Compute and Cache to Disk.

The user cache stores the computed Bifröst simulation as files on disk per frame. The Bifröst simulation reads the cache files each frame, instead of recomputing the simulation. Cache files are created for each cacheable Bifröst object, which includes liquid, aero, foam, and solids (collision objects), as well as optionally for the output mesh.

The user cache is intended for the final, approved simulation, unlike the temporary scratch cache which is meant for scrubbing and playback on the fly. For more information about generating a user cache for a Bifröst simulation, see Work with Bifröst user caches.

Cache directory

The parent directory in which to store the user cache files. The default is the cache/bifrost/<scene name> subfolder of the current project folder.

Cache name

The directory containing cache files associated with the main container node. For example, this directory can include cache files from liquid, foam, solid, and guided simulation objects. The cache files for each object are stored in sub-directories organized by their object type, such as "voxel_liquid" for liquids. By default, the full path is cache/bifrost/<scene name>/<container name>/<object type>.

The file names consist of the Bifröst object type appended by "-volume" for voxel caches, "-particle" or "-flipParticle" for particle caches, and the frame number.

By default, the full path to user cache files, including Cache directory and Cache name, is: cache/bifrost/<scene name>/<container name>/<object type>. You can change the cache name or directory if you want to create multiple caches with different settings to compare them.

Cache format

The format of the cache files.

Cache Elements

• Simulation caches the particles and voxels of the fluid as well as other elements involved in the simulation, such as colliders (solids), guides, foam, and so on.
• Mesh caches the output fluid mesh per frame. You do not need to enable meshing on the Bifröst shape to generate this cache, but the cache will not be read into the scene until you do enable it.

Compression format

Sets the compression quality of the cache files.

Cache time range

Specifies the range of frames to cache. Note that the range must begin at the Start Frame of the simulation set in the Simulation Attributes group of the main bifrostLiquidContainer or bifrostAeroContainer node.

Render settings

Uses the Frame Range set on the Common tab of the Render Settings window.

Time slider

Uses the current playback range visible on the time line.

Start/End

Uses the specified Start and End frames.

Write Mode

Sets the cache write mode for all cacheable Bifröst objects in the scene for frames specified by the Cache time range. You can override the Write Mode on individual objects using their Cache Control attributes. See Bifrost Caching attributes.

• Write All creates a user cache file each frame and overwrites existing cache files.
• Write from last matching frame automatically determines the last cached frame that matches the current simulation settings, and restarts caching from that frame onward.

  Use this mode to continue generating a liquid cache that failed for any reason, or to append to an existing liquid cache. See Automatically restart caching from the last cached frame (Bifröst liquid only).

• Read/Write reads existing cache files each frame, while creating files for uncached frames based on the previously cached frames.

  Use this mode when appending to a user cache, or when creating a user cache for a foam simulation based on an existing liquid cache that you do not want to recompute. See Append to an existing Bifröst user cache.