Baking Physics Simulations

Baking refers to the act of storing or caching the results of a calculation. The result of a simulation is automatically cached to memory when the animation is played, so that the next time it runs, it can be replayed more quickly by reading the results from the memory.

If you bake the simulation the cache is protected, and you will be unable to change the simulation settings until you clear the baked frames by clicking Free Bake.

It is generally recommended to bake your physics simulations before rendering. Aside from no longer needing to go through the time-consuming process of simulating again, baking can help prevent potential glitches and ensure that the outcome of the simulation remains exactly the same every time.

Note

Most physics simulators in Blender use a similar system, but not all have exactly the same settings available. All the settings are covered here, but individual physics types may not provide all these options.

Options

Two different caches stored simultaneously.

Caches List

Blender allows for storing and managing multiple caches at once for the same physics object. You can manage the caches with this list view. Double-click the cache entry to give it a name.

Each cache can have a name. Double-click the cache entry to give it a name. If this name is given, any disk cache will be stored in files starting with that name. For example, a cache named MyCache will be stored in MyCache_xxxxxx_yy.bphys.

If the cache does not have a name (which is the default), the filename of the cache will depend on the object it is attached to, although this is not immediately obvious. For example, a cache on an object Cube will be stored in 43756265_xxxxxx_yy.bphys, where 43756265 is determined by the object name.

Warning

When there are multiple caches on one object, always specify a Cache Name. As described above, the filename of an unnamed cache is determined by the name of the object it is attached to. As a result, an object with multiple physics systems that all have an unnamed cache will cause conflict and can result in losing cache files.

External

Allows you to read the cache from a drive using a user-specified file path.

Note

The cache name in Caches List and the Index has to exactly match the external cache files name in order to work. The cache files name format is name_frame_index.bphys.

• Index

  The index number of cache files. (The last two digits of the files name.)

  Path

  Select the directory path to the cache files.

Disk Cache

The cache of a baked simulation will be stored inside the blend-file when you save it. When Disk Cache is checked, Blender will save the cache separately to the drive in a folder named blendcache_[filename] alongside the blend-file. (The blend-file must be saved first.)

Note

When using Library Overrides, data-blocks only support Disk Cache storage.

Use Library Path

Share the disk cache when the physics object is linked into another blend-file. When this option is enabled, linked versions of the object will reference the same disk cache. Otherwise linked versions of the object will use independent caches.

Compression

The compression level for cache files. Some physics caches can be very large, Blender can compress these caches in order to save space.

• None

  Do not compress the cache.

  Light

  Compression will optimize the speed of compressing/decompressing operations over file size.

  Heavy

  Compression will result in smaller cache files more than Light, however, requires more CPU time to compress/decompress.

Start

Frame on which to start the simulation.

End

Frame on which to stop the simulation.

Note

The simulation is only calculated for positive frames in between the Start and End frames of the Cache panel, whether you bake or not. So if you want a simulation that is longer than the default frame range you have to change the End frame.

Cache Step

Interval for storing simulation data.

Note

Some physics systems (such as particles) allow for positions to be stored only on every nth frame, letting the positions for in-between frames be interpolated. Using a cache step greater than one will result in a smaller cache, but the result may differ from the original simulation.

Baking

Bake

Start baking. Blender will become unresponsive during most baking operations. The cursor will display as a number representing the progress of the baking. You need to be in Object Mode to bake.

Free Bake

Mark the baked cache as temporary. The data will still exist, but will be removed with the next object modification and frame change. This button is only available when the physics system has been baked.

Calculate to Frame

Bake only up to the current frame. Limited by End frame set in the cache settings.

Current Cache to Bake

Store any temporarily cached simulation data as a bake. Note that playing the animation will try to simulate any visible physics simulations. Depending on the physics type, this data may be temporarily cached. Normally such temporary caches are cleared when an object or setting is modified, but converting it to a bake will “save” it.

Bake All Dynamics

Bake all physics systems in the scene, even those of different types. Useful for baking complex setups involving interactions between different physics types.

See Bake.

Free All Bakes

Free bakes of all physics systems in the scene, even those of different types.

See Free Bake.

Update All to Frame

Bake all physics systems in the scene to the current frame.

See Calculate To Frame.