Adding custom assets to Resource Pack

Polymer has builtin support for adding and overriding assets to generated resource pack. You can do it in multiple ways.

Base folders

You can add your assets to polymer/source_assets and/or polymer/override_assets folders. These folders might not exist by default so you will need to create them by hand. The source_assets folder is applied first, before any mod. The override_assets folder is applied last, after generation/copying of most other files. For most cases, you likely want to use source_assets. These folders both use vanilla resource pack structure, with pack.mcmeta and pack.png being optional and replacing default Polymer-generated one.

Adding resource packs zips or mods

To add custom resource packs, open config/polymer/resource-pack.json file. Then look at list in "include_zips" and add paths to zips with your custom resource packs. These paths are relative to server's root folder. To copy assets from mods, you can either use the zip method or add their modid to "include_mod_assets". Unlike with method above, the only copied folder is included assets folder, ignoring anything else, making it more suitable for merging resource packs without adding invalid metadata.

This setting will only update on server restart.