Ask : Caching

Where does RealFlow | Cinema 4D store the cache files?

Click on the "Scene" object and open its "Cache" tab in Cinema 4D's "Attributes" manager. There, specify the "Cache Folder".

You normally do not have to worry about the cache folder's content, because all data will be managed by RealFlow | Cinema 4D during simulation.

How do I get rid of my simulation files easily?

Click on the "Scene" object and open its "Cache" tab in Cinema 4D's "Attributes" manager. There you will find a "Remove Cache" button. You'll be asked to confirm your action, because it cannot be undone.

Will the cache files be overwritten when I hit "Cache Simulation" or "Cache Meshes" again?

Yes. We therefore recommend specifying new cache folders if you want to save different versions of a simulation.

My fluid/rigid/elastic containers and meshes have equal names. Does this affect caching?

Yes! All particle and mesh data will be written to the same files. This means that existing files will be overwritten again and again. To avoid overlapping or overwritten data, the simulated nodes must have unique names.

I'm using a shared cache folder for different scenes. Does this affect caching?

It's definitely better to use seperate cache folders for different scenes and even for different simulations of the same project. If you have to use a shared folder for whatever reason then you have to be careful with naming:

Always use unique and meaningful names, because otherwise already cached files will be overwritten!

Isn't there a way to specify a default cache folder?

You can define a base path in Cinema 4D's preferences under "RealFlow". For the actual cache data we recommend specifying a separate folder for every scene, because otherwise existing data might be overwritten.

Can I use SSD drives with RealFlow | Cinema 4D?

In terms of simulation and read/write speed it definitely is a good idea to have a fast SSD drive, but these devices have a limited amount of bytes to be written – in many cases something between 250 and 500 TB. Beyond this limit data can only be read, but no longer be written. If you consider that a large simulation can produce several gigabytes of data this lifespan is a serious thing to think about. We therefore recommend modern hard disk drives. They are slower, but much more reliable. But in the end this decision is completely up to you.

Why are the cache files so big?

What is the difference between the different Deformer Cache modes?

You can select between two (actually three if you combine them) options to cache the rigid/elastic simulations. Let us show you the advantages and disadvantages of every method:

• Point Level Animation (PLA) Pros

• • Point Level Animation is supported by most if not all Cinema 4D compatible render engines.
  • Simulation results are kept in the very same Cinema 4D document. 
  • No extra file output is necessary.
  • Original geometry remains intact, while the duplicated geometry preserves all the characteristics of it (hierarchy, tags, materials, etc.).

• Point Level Animation (PLA) Cons

• • A new duplicate of the geometry is generated every time the cache process is executed. Older simulations need to be removed manually if no longer necessary.
  • The original object needs to be manually disabled after the caching process to avoid misunderstandings.
  • Cinema 4D document size grows linearly with the number of simulated frames and the number of vertices of the deformed geometries.

• Export File Sequence Pros

• • Document size does not grow because the cached information is saved outside the C4D file.
  • Modifications are applied to the original objects. 
  • Caching process is similar to the rest of RealFlow nodes (fluids, rigids, elastics, and meshes).

• Export File Sequence Cons

• • Motion blur does not work unless you add a Point Cache tag per object.
  • The amount of written files in the cache folder can be very large.
  • Exported files are not a standard format and cannot be reused for other purposes.
  • Nodes with the same name will generate files with the same name. This is an issue that cannot be avoided by manual renaming in some cases:
    For example: a Cloner which duplicates a geometry hierarchy with a depth of more than one level.

In any case, the default mode is "Point Level Animation (PLA)".

I have cached a rigid/elastic simulation, and now the cache folder contains thousands of files. Is this really necessary?

If "Export File Sequence" is selected as the Deformer Cache Mode, yes, it is necessary. Let us explain you the reasons with an example, where a sphere will be influenced through an elastic deformer:

• The "Elastic" deformer fills the sphere with particles.
• RealFlow | Cinema 4D simulates the behaviour of the particles in terms of motion and deformation.
• This information will be transferred to the sphere through the "Particle Skinner" feature.
• When you cache the simulation, the "Elastic" container files only contain the particle data, but not the deformation.
• The deformation, on the other hand, has to be saved for each object individually in a separate file sequence.
• Only this workflow makes sure that you will be able to playback cached simulations and render them after you have reopened a scene.

The disadvantage is a huge amount of files. With 100 elastic objects over 200 frames you will get 20,000 individual deformation files, for example.

You can select "Point Level Animation (PLA)" as Deformer Cache Mode in order to avoid writing so many files.

Which file formats are supported by RealFlow | Cinema 4D?

• Fluid particle and mesh files are stored as a sequence of Alembic files.
• Rigid and elastic deformer files are stored in a propietary file format. This is a temporary approach and will be changed in one of the upcoming patches.
• Wet-dry maps are stored as a sequence of PNG files.