u/music_devotee_tybg

1. download the correct zip of plugins
This is the correct download link: https://github.com/supercollider/sc3-plugins/releases

I previously got confused because this similarly named link is actually for developers who want to make plugins: https://github.com/supercollider/sc3-plugins

2. Once you have it downloaded extract the file to the following file path:

For Windows, :

C:\Users\<username>\AppData\Local\SuperCollider\Extensions

where <username> is your Windows account name.

A Windows user can verify it from within SuperCollider by running:

Platform.userExtensionDir;

which will print something like:

C:\Users\Caleb Crittenden\AppData\Local\SuperCollider\Extensions

If the folder doesn't exist yet, they can create it with:

File.mkdir(Platform.userExtensionDir);

If the folder already exists, File.mkdir will simply return false, which is normal and just means there's nothing to create.

Windows: C:\Users\Caleb Crittenden\AppData\Local\SuperCollider\Extensions

Apple:

For macOS, the user Extensions folder is:

~/Library/Application Support/SuperCollider/Extensions

where ~ is the user's home directory.

A Mac user can verify it from within SuperCollider by running:

Platform.userExtensionDir;

which will print something like:

/Users/username/Library/Application Support/SuperCollider/Extensions

If the folder doesn't exist yet, they can create it with:

File.mkdir(Platform.userExtensionDir);

3. After copying the plugin files into your Extensions folder, SuperCollider needs to rebuild (or recompile) its class library before it can recognize the new UGens and classes. Until you do this, plugins such as Decimator will not be available.

To recompile the class library:

• Windows/Linux: Press Ctrl + Shift + L
• macOS: Press Command (⌘) + Shift + L

Alternatively, you can select Language → Recompile Class Library from the menu bar.

The Post window will display messages indicating that SuperCollider is recompiling the class library. If the compilation completes successfully, the newly installed plugins are ready to use. If any errors appear, check that the plugin files were copied into the correct Extensions folder and that you downloaded the compiled release for your operating system rather than the source code.

4. To verify that the installation was successful, evaluate:

Decimator

If the plugin is installed correctly, SuperCollider will return the Decimator class. If you receive "Class not defined", the plugin was either not installed correctly or the class library has not yet been recompiled.