grid inventory system · v2.0.0

Overview

A production-ready, drag-and-drop grid inventory for Unity — multi-cell items, rotation, stacking, equipment, shops, and one-call JSON saves. This is the full manual; it is updated with every release.

Grid Inventory System multi-inventory demo with player, shop, and stash grids — The multi-inventory demo: player grid, shop, and stash trading through the pluggable economy.

What's in the box

System	Description
Grid inventories	Diablo/Tarkov-style 2D grids with multi-cell footprints (1×1 up to 2×4 and beyond), right-click rotation, stack splitting and merge-on-drop. Grid inventories →
Slot inventories & hotbar	Minecraft-style fixed-slot containers, plus a hotbar variant that raises `OnSlotActivated` from the digit keys. Equipment & hotbar →
Equipment paper-doll	An 11-slot RPG loadout with per-slot type validation — helm, chest, rings, weapons, and more.
Shops, stash & economy	Player, Shop, and Stash inventory types with right-click buy/sell and a pluggable `IEconomy` interface. Shops & economy →
Save / load	Crash-safe JSON persistence with automatic backups, optional auto-save, and save-format migration. Save & load →
Editor tooling	Item Creator with live tooltip preview, Item Browser with bulk edit, one-shot in-scene generators, and one-click demo scene builders. Editor windows →

Architecture at a glance

Four layers, each replaceable without touching the others:

How the pieces fit

text

ItemData (ScriptableObject)        what an item IS — name, icon, footprint, rarity
        │
ItemInstance                       one occurrence of an item — position, stack,
        │                          rotation, condition, custom name
        │
Controllers (MonoBehaviours)       own the data & raise events
  ├── InventoryController          2D grid, multi-cell placement
  ├── SlotInventoryController      fixed slot array
  │     └── HotbarController      + digit-key activation
  └── EquipmentController          typed paper-doll slots
        │
UI binders                         render state & handle drag/drop
  ├── GridUI                       for grids
  ├── SlotInventoryUI              for slots / hotbars
  └── EquipmentPanelUI             for equipment

All controllers implement the IInventory interface, which is what lets items drag between a grid, a hotbar, and an equipment panel without any glue code. Tooltips and the stack-split dialog are self-spawning singletons — they need zero scene wiring.

// note

Everything lives in the flat InventorySystem C# namespace. Add using InventorySystem; and you have the whole API.

Where to go next

If you want to…	Description
Install it	Installation & setup — requirements plus the two one-time steps for a clean project.
See it running	Demo scenes & controls — the four shipped scenes and every mouse/keyboard interaction.
Build your own	Quick start — a working inventory in your scene in about five minutes.
Look something up	API reference — every public type, method, and event on one page.