Liquid Resimulation Input/Output Error

[joshclos]

When resimulating a liquid in order to update foam/splash, I am attempting to write out a new cache instead of overwriting the existing cache but receiving errors. The documentation linked below suggests that I could set the input path to my existing simulation and change the output to a new location. However, when I change the input and output paths during a resimulation, I receive two error messages. The first error message warns that the preview and render will not match since the paths are different (although the documentation states that when you're in resimulation mode, it reads the preview from the output path instead of the input path), and the second error message after that simply reads "Can't load the Resimulation source file!"

In my case, when I only have an output path, or when I use all default paths, the resimulation overwrites but it works properly when overwriting so this issue seems to only occur when I have different input/output paths. For the time being, I've been copying my original cache to a backup folder before resimulation as a work-around. The documentation suggests that by default, it should create a new file in the default directory with "_resim" added to it but I haven't been able to achieve that result even while using all default paths.

Relevant Documentation:
https://docs.chaosgroup.com/display/...orResimulation

Anyone else experienced this?
Josh Clos

[Ivaylo Katev]

the liquid resimulation and the smoke/fire resimulation have different behavior, there are two reasons for this
- unlike the fire/smoke resimulation, the liquid resimulation does not overwrite any source channel, i.e. the result will be the same if you run it again, this makes the second cache file pointless
- using the same cache file for resimulation is quite faster than using different cache files, because only the resimulated particles are replaced

[joshclos]

That makes sense. In my case, the second cache file had a purpose; it was meant to stay organized and save potential future simulation time. I wanted to keep the initial foam/splash sim as an option and generate an additional option to show the client to choose from. Yes, I could just change the settings back, but I would have to simulate again. I rarely delete any cache files while working on a shot because very often, we come back to a previous version, which wouldn't exist anymore if I overwrite it.

Faster simulation is always the goal so if it's faster to overwrite, then that's the way to go. I will just continue backing up the original cache before overwriting. The issue there is organization because if I have "v001" then I overwrite-resim it to have new foam, I would have "v001_backup_001" and a new "v001." That would get messier if I have to resim multiple times as I would just be incrimenting the backups of "v001." For a cleaner workflow, I'll copy the cache contents of "v001" into a "v002" folder and rename the files to have the "002" suffix before overwriting. That way I can have nice clean versioning "001, 002, etc." My last simulation went up to 67 versions so I try to keep the files as clean as possible.

Thanks for your reply!
Josh