Prefabs by ldlework pre-release

My patches are on my PC’s drive in the default patches folder in Rack’s installation folder. I do have 990 patches, although the number shouldn’t make a difference.

I’ll try the devmode option and let you know if I spot something awry.


[48.745 info C:/_Projects/VCVRack/Rack-SDK-2/plugins/vcv-prefabs/src/models/PatchSource.cpp:22 loadFile] [Prefabs] Loading patch from ./patches/Data bender maybe.vcv
[48.746 info C:/_Projects/VCVRack/Rack-SDK-2/plugins/vcv-prefabs/src/models/PatchSource.cpp:29 loadFile] [Prefabs] Unpacking patch to ./prefab-tmp
terminate called after throwing an instance of 'rack::Exception'
  what():  Unarchiver could not open archive ./patches/Data bender maybe.vcv: Unrecognized archive format

The exception is being thrown because the module is trying to unarchive a v1.1.6 patch, which of course Rack v2 allows the loading of. FYI, the problem with this particular patch is it’s missing 3 modules that aren’t in the relevant v2 plugins.

So maybe if the exception, instead of terminating, it could ignore this as it would be indicitive of pre v2 patches?

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with the latest build VCV crashes each time I want to add Prefab
here on Win11

I find this in log.txt:

rsmus7, can you run with -d and see if it produces any more interesting output?

Also stay tuned, I think Steve figured out the problem!

I have updated the Nightly build to support Rack V1 patches.

Please try it out and let me know what happens!

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the -d option doesn’t work here, as I have a different location for my documents folder and rack with -d doesn’t load this folder and the patches and plugins I normally use.

my rack patch still crashes with the latest nightly

maybe it crashes, because I have the documents folder of Win on another hdd partition
( not on C: ) and Prefab expects it to be in the default location?

I had the same issue. cd to Rack installation folder.

Then use ./Rack.exe -d -u [drive_letter:/path/to/plugins/folder]

Might need the use of single quotes ' if path has a space e.g. 'c:/Program Files/VCV/Rack2 Pro'

I am using the assets::user function to find your user directory so I am unsure why having the user directory on a different drive-letter would cause the problem.

The debug logging for the latest version will be helpful if Steve’s trick works for you.

Steve is it still crashing for you?

No, all good here now.

NB: -d development mode sets the system and user folders to the current working directory, so one needs to specify where the actual folders are.

What I use

./Rack.exe -d -u .

works for me as I have both plugins and patches folders in the installation folder.

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Hey all, I just pushed up some changes.

  • Multiple Prefab module are no longer a problem, they all share the single global widget.
  • All Prefab modules share a single set of settings. So changing it here changes it everywhere.
  • Once loaded the Prefabs Widget is now permanent and persists across patch loads.
  • Prefabs and patches with missing modules can’t be clicked and show tooltip with missing modules.
  • V1 patches now supported.
  • Some reliability fixes.

I am working on this.

Hey there joop,

I added this feature. Try out the latest build.

Edit $your_rack_directory/prefabs.json

Update the extraPrefabSources or extraPatchSources with array pairs of slug and `path:

  "extraPatchSources": [

And they’ll show up under the Plugin prefabs or Plugin patches sections.

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I’m noticing about a 2-3 second lag in opening the menu on the floating dial, maybe it’s because I have a lot of selections and favorites? Running 2.2.2 on Mac Air M1 under Rosetta.

Yeah, I just came here to mention now that we’re processing patches, we’re doing a lot more work on startup. The more patches you have the longer startup will be.

I will attempt to optimize things as my exploration of features settles down and we squash some more bugs. Please let me know if the delay makes the plugin unusable.

That said, patches are also now included in search results on the latest build.

Ah, cool, sounds good, thanks for investigating. It does affect usability a bit, it’s not terrible right now but it is noticeably slower than the native right click menus.

One concern is the more I use this, the more I’ll save, and would that add to the lag, hehe?

Could there be an option to not parse patches? This way, it’s only slower when that option is active.

Also, I’d love an option to replace the right click built-in library browser with the Prefabs menu, similar to Stoermelder MB.

In the Favorites modules list, is it possible to list the Brands in alphabetical order? Not sure how it’s being ordered currently.

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Hey, try the latest build.

I’ve added a context-setting to the module to toggle refreshing every time.

If it’s disabled, the refresh will only happen when you toggle the widget on and off with the module’s button.

I’ve made a note to look at brand sorting.

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i’d just like to throw out there that i support this idea.


Looking at MB’s code, it does seem like it is not all that hard to replace the browser.

Is the idea that the menu would just appear anywhere you on empty space?

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this is certainly how i imagine it working.

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Yeah, exactly. Simple right click ftw.

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