Guidebook Modelling Shop Item

Ship buyable hardware with your own mesh: folder → files → spec → shop. DTO: GregModPack.ShopItem (src/gregCore.Core/Mods/GregModPack.cs).

1. Folder + files

UserData/gregCore/Mods/Lua/<modId>/my_cooler/
├── cooler.obj        (≤ 64 MB, static, triangulated)
├── cooler.png        (texture)
└── cooler_icon.png   (shop icon)

C# mods use a pack folder with the same content (any path you pass as folderPath).

2. Lua registration

function on_init()
    local ok = greg.items.register_shop_item("my_cooler", {
        name = "Ice Cooler", price = 499, xp = 10,
        size_u = 2, mass = 5, scale = 1,
        model = "cooler.obj", texture = "cooler.png", icon = "cooler_icon.png",
        type = "ServerCooler",
    })
    greg.ui.log_info("Cooler registered: " .. tostring(ok))
end

3. Spec reference (exact DTO mapping)

Spec key	DTO field	Default	Notes
name	ItemName	""	Display name (required, non-empty in practice)
price	Price	0	Shop price
xp	XpToUnlock	0	XP gate
size_u	SizeInU	1	Rack units
mass	Mass	1	Physics mass
scale	ModelScale	1	Mesh scale multiplier
model	ModelFile	""	Required .obj filename in the folder
texture	TextureFile	""	Texture filename in the folder
icon	IconFile	""	Shop icon filename
type	ObjectType	""	Must parse as PlayerManager.ObjectInHand (case-insensitive); garbage → vanilla default
collidersize / collidercenter	ColliderSize / ColliderCenter	empty	Optional float arrays; match mesh bounds

Keys work in snake_case or PascalCase (LuaItemsModule aliases + case-insensitive binding). Returns bool; false + log line on any failure — never a crash.

4. C# equivalent

var dto = new GregModPack.ShopItem
{
    ItemName = "Ice Cooler", Price = 499, XpToUnlock = 10,
    SizeInU = 2, Mass = 5f, ModelScale = 1f,
    ModelFile = "cooler.obj", TextureFile = "cooler.png",
    IconFile = "cooler_icon.png", ObjectType = "ServerCooler",
};
bool ok = GregCustomItems.RegisterShopItem(folderPath, folderName, dto);
if (ok) { var prefab = GregCustomItems.GetPrefab(folderName); /* variants/overlays */ }

Requires ModLoader.instance (scene ready — register after load, not in a static constructor). GetPrefab(folderName) returns the loaded template prefab (GetModPrefabByFolder) for variants.

5. IDs + verify

• Item IDs from the high ranges (100, 1000/2000/3000, 9001+), never reused — saves reference them (see Developer Shop Items).
• Verify: loader log shows Custom shop item registriert: 'Ice Cooler'; in-game shop → “HL Mods” section → buy → checkout → place; reload the save with the mod present, then removed (vanilla must still load).

Checkpoint

• register_shop_item returns true; log line present; item visible/buyable/placeable.
• Scale, size_u, and collider feel right next to vanilla hardware.

Next: Guidebook Modelling Static Item.