Cache

Reference

Panel:: Physics ‣ Fluid ‣ Cache
Type:: Domain

The Cache panel is used to Bake the fluid simulation and stores the outcome of a simulation so it does not need to be recalculated.

Baking takes a lot of compute power (hence time). Depending on the scene, it is recommended to allocate enough time for the baking process.

If the mesh has modifiers, the rendering settings are used for exporting the mesh to the fluid solver. Depending on the setting, calculation times and memory use might exponentially increase. For example, when using a moving mesh with Subdivision Surface as an obstacle, it might help to decrease simulation time by switching it off, or to a low subdivision level. When the setup/rig is correct, you can always increase settings to yield a more realistic result.

Note

Fluid simulations use their own cache. All other physics simulations make use of the General Baking operators.

Cache Directory: Directory to store baked simulation files in. Inside this directory each simulation type (i.e. mesh, particles, noise) will have its own directory containing the simulation data.

Type

The type of the cache determines how the cache can be baked.

Replay: The cache will be baked as the simulation is being played in the viewport.
Modular: The cache will be baked step by step: The bake operators for this type are spread across various panels within the domain settings (e.g. the bake tool for the mesh can be found in the Mesh panel).
All: The cache will be baked with a single tool. All selected settings will be considered during this bake. The bake tool for this type can be found in the Cache panel.

Important

“Replay” only works when the Playback Sync mode is set to “Play Every Frame”. If you need to use “Frame Dropping” or “Sync to Audio”, consider using the “Modular” or “All” options below.

Start: Frame on which to start the simulation. This is the first frame that will be baked.

End: Frame on which to stop the simulation. This is the last frame that will be baked.

Note

The simulation is only calculated for positive frames between the Start and End frames of the Cache panel. So if you want a simulation that is longer than the default frame range you have to change the End frame.

Offset: Frame offset that is used when loading the simulation from the cache. It is not considered when baking the simulation, only when loading it.

Use Resumable Cache: Extra data will be saved so that you can resumed baking after pausing. Since more data will be written to drive it is recommended to avoid enabling this option when baking at high resolutions.

Volume File Format

File format for volume based simulation data (i.e. grids and particles).

Uni Cache: Blender’s own caching format with some compression. Each simulation object is stored in its own .uni cache file.
OpenVDB: Advanced and efficient storage format. All simulation objects (i.e. grids and particles) are stored in a single .vdb file per frame.

Mesh File Format Liquids Only

File format for the mesh cache files.

Binary Object: Mesh data files with some compression.
Object: Simple, standard data format for mesh data.

Bake All, Free All

This option is only available when using the Final cache type. Bake All will run the simulation considering all parameters from the settings (i.e. it will bake all steps that can be baked individually with the Modular cache type at once).

The progress will be displayed in the status bar. Pressing Esc will abort the simulation.

Once the simulation has been baked, the cache can be deleted by pressing Free All. It is not possible to pause or resume a Bake All process as only the most essential cache files are stored on drive.

Advanced

Compression Volumes OpenVDB Only

Compression method that is used when writing OpenVDB cache files.

None: Cache files will be written without any compression.
Zip: Cache files will be written with Zip compression. Effective but slower than Blosc.
Blosc: Cache files will be written with Blosc compression. Multithreaded compression, similar in size and quality to Zip compression.

Precision Volumes OpenVDB Only

Precision level that is used when writing OpenVDB cache files.

Full: Volumetric data (e.g. grids, particles) will be written with full precision (32-bit).
Half: Volumetric data (e.g. grids, particles) will be written with half precision (16-bit).
Mini: Volumetric data (e.g. grids, particles) will be written with mini float precision (8-bit) where possible. For cache data where this is not possible, 16-bit floats will be used instead.

Export Mantaflow Script: Export the simulation as a standalone Mantaflow script when baking the scene (exported on “Bake Data”). Usually, only developers and advanced users who know how to use the Mantaflow GUI will make use of this functionality. Use a Debug Value of 3001 to enable.