Resume a simulation from a cached file

Resuming a simulation from a cached file lets you run a simulation once for a number of frames, and then use the cached result as the new starting point for the simulation.

1. Cache the initial part of your simulation to file, for example, using the file_cache node.

   • The cache must contain all properties required for the simulation, so for best results leave properties set to the default value *.
   • The supported formats are .bob and .vdb.
   • Once the files have been saved to disk, the file_cache node is no longer required. You can set it to Passthrough Mode if you want to keep it in the graph for caching the final result later on.

2. Right-click on the additional_settings input of the simulation graph's settings node, choose Create Node, and then select Simulation:Common:set_initial_state. A set_initial_state node is added and connected.

3. Set the filename to the cached file that you want to use as the initial state of the simulation.

4. Optionally, set set_to_frame to the scene frame that you want the initial state to be used on (if it is different from frame 1).

   • This becomes the minimum scene frame for any simulation to occur, even if other nodes like sources or colliders are set to start at an earlier frame.
   • Source and collider nodes with later start frames will begin on their specified frames as usual.

5. You can modify any parameters on the other simulation nodes, if desired. The result is as if the simulation was run with the original settings up to the initial state, and then continued with new settings.