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Baking Physics Simulations
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:term:`Baking` refers to the act of storing or caching the results of a calculation.

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.

.. A Screenshot of the baking interface is intentionally omitted, as it
   the available options vary slightly between different physics systems.

.. 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.

Compression
   Compression level for cache files. Some physics caches can be very large (such as smoke).
   Blender can compress these caches in order to save space.

   None
      Do not compress the cache.
   Light
      Compression optimizes 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.
External
   Read and write the cache to a drive using a user-specified file path.

   Index Number
      This number specifies which cache should be used
      when the specified cache directory contains `multiple caches`_.
      ``0`` refers to the top-most cache, ``1`` to the second from the top,
      ``2`` to the third, and so on.
Use Lib Path
   Share the disk cache when the physics object is
   :doc:`linked </data_system/linked_libraries>` into another blend-file.

   When this option is enabled, linked versions of the object will reference the same disk cache.
   When disabled, linked versions of the object will use independent caches.

Start
   Frame on which to start the simulation.
End
   Frame on which to stop the simulation.

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.

.. _physics-bake:

Bake
   Start baking.
   Blender will become unresponsive during most baking operations.
   The cursor will display as a number representing the bakes' progress.

.. _free-physics-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.

.. _calc-physics-bake-to-frame:

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 :ref:`Bake <physics-bake>`
Free All Bakes
   Free bakes of all physics systems in the scene, even those of different types.

   See :ref:`Free Bake <free-physics-bake>`.
Update All To Frame
   Bake all physics systems in the scene to the current frame.

   See :ref:`Calculate To Frame <calc-physics-bake-to-frame>`


Multiple Caches
===============

Blender allows for storing and managing multiple caches at once for the same physics object.

.. figure:: /images/physics_baking_multi_cache_interface.png

   Two different caches stored simultaneously.

Caches can be added and removed with the :kbd:`Plus` and :kbd:`Minus` buttons.
Renaming a cache can be done by either double clicking or pressing :kbd:`Ctrl-LMB` on the desired cache.