Custom Charms

Creating the icons

INFO

This section assumes that you have a unity project set up and you know how to create asset bundles. If not, follow this tutorial.
Custom Charms don't require icons, but it means that they will be blank in the equip menu.

TIP

In Cuphead, icons are 80x80 pixels, and included in a 3 frame animation that switches every 0.07 seconds.

1. Import your icons to Unity, and add them to a sprite atlas by following this tutorial.
2. Put the sprite atlas in an asset bundle and press Ctrl+G to generate it.
3. Take the generated bundle and put it in your mod's Assets directory.

Adding the charm

Registering charms is done using the EquipRegistries.Charms.Register method.
Here is a base example for registering a charm:

string atlasPath = "Blender:charm_icons\\atlas";
string charmId = "charm_shield";
Charm shield = EquipRegistries.Charms.Register(charmId, new EquipInfo()
    .SetAtlasPath(atlasPath)
    .SetNormalIcons(["shield0", "shield1", "shield2"]));

Here, atlasPath is the ModName:BundleName\\asset_name.
charmId is the id your charm will be registered with, it must be unique.
asset_name is the name of your atlas as created in Unity. And can be null if you don't want any icons, you also don't have to call SetNormalIcons if you don't have any.
Lastly, SetNormalIcons takes an array of the sprite names as imported to Unity.

INFO

Blender doesn't add new charm slots in the equip menu, it adds new pages to it.
If the player has unlocked the charm, by calling PlayerData.Data.Gift or by purchasing it in the shop, They can go downwards in the equip menu to reach the next page.

Making it useful

To check if the player has the charm equipped, you can use

if (PlayerData.Data.Loadouts.GetPlayerLoadout(player_id).charm == CHARM_INSTANCE)
{
    //Execute your code.
}

This can be called whenever you want in specific game events to add functionality to your charm.
CHARM_INSTANCE is returned by the Register method.