Caching stores the simulation frames from an ICE point cloud or ICE simulated deformation into an action source. Caching stores the object’s local ICE attributes values in a file sequence. You can cache an ICE simulation in the same way as you can with rigid bodies, using the Simulation Time Control property editor.
Caching the simulation lets you easily try out different variations of a simulation because it stores the current simulation frames into their own action source. You can create an action source for each variation you want.
Caching also allows you to scrub the cursor back and forth in the timeline and get the correct state, and to play the simulation backwards.
When the simulation is cached, each frame that has been played is evaluated and stored. This means that you need to play through the whole simulation (with the All frames button selected in the timeline, and not RT) to cache each frame of it. If you change something in the simulation, all subsequent frames are affected, so the cache is emptied and you need to cache again to update it with the changes.
You can delete or mute the original simulation on the object to play the simulation as an animation in the mixer, or delete the simulation and reapply the action source back to the particles as animation.
Playing cached files is usually faster than playing back the simulation, but here are two reasons why it might not be:
• The speed of the network on which your cache files are stored, which may be slow at times.
• Simulation uses all cores of a machine, while caching uses only one.
Action Sources
When you are satisfied with the currently cached simulation, you can create an action source for it to keep with the model. You can cache one action source per model, which lets you import and export models with their cached simulation intact.
Once you have the simulation cached in an action source, you can load the action source onto a track in the animation mixer (thus creating an action clip) and use it like any other action clip. For example, you can load many simulation sources on tracks in the mixer, then play each one separately (solo), or mix the weights of two or more simulations together.
For information in general about action sources in the animation mixer, see Actions [ Nonlinear Animation ].
To cache the simulation
1. In the explorer, select either the Environments or Curr. Envir. as the scope. Expand the current Simulation Environment.
2. Click the Simulation Time Control icon to open its property editor and select the Caching option.
3. Select the Play Mode.
You can cache the simulation using either the Standard or Live play mode. If you’re caching in Live mode, every change you make is updated and stored in the source file. However, when doing a final render of the scene and you are doing distributed rendering or using motion blur, it’s a good idea to use the Standard mode for caching.
4. On the Caching Files tab of the property editor, select the Template and Version String you want to use for the cache file.
The information here is taken from the File Cache Path Template preferences you have set up in the Simulation Preferences (see Setting the Default Paths for Cache Files). You can view or change the paths you have set up there.
5. Click the Save caches to mixer button to open the Store Environment Cache in Mixer dialog box.
6. In this dialog box, enter an Action Name for the action source that contains the cached simulation. This source is kept in the model’s Mixer > Sources > Animation node. Then if you export your model, the cached simulation is included with it.
If you like, you can select the Add Clip to Mixer option to automatically apply the action source as an action clip in the model’s animation mixer.
7. Play the whole simulation to cache each frame of it, or play only the frames you want to cache.
Make sure that the All frames button is selected in the timeline, and not RT (real time). See Playing Back All Frames or Playing in Real Time for more information.
8. The file is stored in the path that you specified on the Caching Files tab.
Once you have created a cache, you can lock it so that its contents can’t be resimulated once it is complete. This is particularly useful when you’re happy with the current state of the simulation and want to make sure that it won’t change. Locking a cache can be of great help before sending it to a render farm, for example.
To lock the cache
• Open the Simulation Time Control property editor for the simulation environment and select the Lock Cache option.
When this option is on, frames that have already been cached are not resimulated.
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