Trying to understand caching in Vellum *novice

[Oidy]

Been getting back on the houdini train, this is my second attenmpt to get onboard from a few years ago. Thanks corona...

Im trying to get comfortable with houdini caching before I start upping grain counts in vellum. I have been using the vellumio node to create test files (saving as .bgeo so far, .sim isnt on the save list) but when I toggle the node on it won't scrub, it just shows as the last frame of the sim, unless I go into the node, then it will play. I have load from disk checked. Can someone walk me through this?

Is it even necessary to cache? Will save to disk in background keep caches after a restart?

Thanks

[anim]

yes, Vellum IO is for caching to disk ideally as .bgeosc or bgeo.sc files, since the files are saved separately from your .hip file you can read them back using Vellum IO or even File SOP, save in Background saves them using a separate thread, but to the specified disk files so yes, you will be able to load them after restart

13 hours ago, Oidy said:

but when I toggle the node on it won't scrub, it just shows as the last frame of the sim

probably because you have specified only a single file path, like $HIP/geo/mycache.bgeosc so that every frame is overwriting that file and at the end it will contain only the last frame

what you need to do it specify sequence $HIP/geo/mycache.$F4.bgeosc, which for every frame will resolve in different file path, therefore each frame will be saved as a separate geometry file, and it will also be read from there using the same logic

14 hours ago, Oidy said:

Is it even necessary to cache?

Vellum Solver SOP or also any DOP network has memory cache and you can specify it's size, so that when you sim by playing timeline, it will cache to memory up to that size and you can see the cache for current dopsim as blue bar on the timeline 

this will allow you to play it back, so it's great for iteratin on relatively quick sims that fit into your memory limit, but being it a memory cache they will not be saved anywhere after you close your scene so it's important to cache to disk before rendering or further processing the data

[Oidy]

Thanks for your reply, Im starting to understand a little better. However I still cant seem to get the cache into a specified location. So if I just type in the field the name of the file and chose a location it wont work? Its fine if I let houdini name the file automatically but that drive just doesnt have enough space.

So far Ive had .bgeo files working ok when houdini names the location. then I checked save checkpoints and Im getting .sim files from a different node. The plan was to buy a dedicated ssd just for sims but Id like to be able to put them there first...argh!

[anim]

14 minutes ago, Oidy said:

However I still cant seem to get the cache into a specified location

what's the path you are putting in there? It should save files to the location you are specifying, that's why the Geometry File parameter is for

also Dopnet Checkpoints have separate parameter to specify where the files will be saved, but no matter what you are in control of the location