Resources

You can append resources when a resource pack is generated in multiple places. Most common is the addToResourcePack function inside a poly. There's also a registerModSpecificResources inside your entrypoint, but it's recommended to use shared values instead.

In all of these cases, you'll get two classes; ModdedResources and a PolyMcResourcePack.

ModdedResources gives you access to the modded files. You can query for a variety of things. It also allows you to access the client jar, giving you access to Minecraft's own assets. Be very careful with copyright issues.

PolyMcResourcePack represents the resource pack that's being generated. You can retrieve files, edit them, and add new files.

Retrieving vanilla assets

Warning

Please use vanilla assets sparingly! PolyMc only copies over very basic stuff that isn't really copyrightable, such as item/generated type item models. The only texture PolyMc copies over is the leather armour texture, which is because all armours need to be inside one file for FancyPants. I highly doubt Mojang is going to take any legal action, after all we're doing some pretty cool stuff, but it might be best to play it safe and give people a heads-up if the resource pack is going to include a bunch of Mojang textures.

PolyMc automatically downloads the client jar, so it can access its assets. You can access these assets via the api using the getClientJar and includeClientJar methods inside ModdedResources. The first one will return only assets inside the client jar whilst the latter will include both vanilla assets and other modded assets.