Unity Perfect-Fit Grid Inventory System

A puzzle-focused, Tetris-style grid inventory system built for Unity using the New Input System and Unity UI (uGUI). Items must be organized to fit perfectly inside the inventory dimensions, with zero empty cells allowed before players can advance to the next level.

This repository leverages ScriptableObjects and a Custom Grid Inspector Tool to design irregular asset structures (like L-shaped pistols or T-shaped blocks) completely code-free.

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🗂️ Script Descriptions

🛡️ GridInventory.cs

Role: Master Grid Controller

• Manages the internal 2D grid matrix backend (bool[,]).
• Handles the structural raycast evaluation from screen-space vectors to localized grid map arrays.
• Manages collision validation check flags before drops occur and verifies completion arrays (IsInventoryPerfectlyFull()).

📦 DraggableItem.cs

Role: Drag-and-Drop & Input Handler

• Implements the EventSystems drag interfaces (IBeginDragHandler, IDragHandler, IEndDragHandler).
• Tracks active drag updates and handles spatial anchoring via top-left evaluation vectors rather than the offset mouse pointer.
• Processes visual-only element rotation tracking through the Unity New Input System in a responsive frame loop.

📄 ItemShapeData.cs

Role: Data Model Asset

• The data model ScriptableObject backend.
• Holds structural bounding box configurations and flat array layouts.
• Instances of this asset represent individual item form-factors dynamically loaded at runtime.

🛠️ ItemShapeDataEditor.cs (Located in /Editor folder)

Role: Custom Shape Developer Tool

• A developer workflow extension script that overrides the standard inspector rendering.
• Replaces the messy default array listing with an intuitive, visual 2D matrix layout of clickable checkboxes.

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🛠️ Unity Engine UI Setup Guide

Follow these sequential setup steps to integrate the scripts into your Unity scene layout:

1. Setting up the Inventory Grid Board

1. In your Hierarchy window, right-click and create a UI > Panel. Rename this object to InventoryBoard.
2. Attach the GridInventory component to InventoryBoard.
3. Configure the GridInventory fields in the Inspector:
   • Grid Width: 4
   • Grid Height: 4
   • Cell Size: 50
4. Set the InventoryBoard RectTransform dimensions to match your mathematical boundaries perfectly: Width: 200, Height: 200 ($4\text{ cells} \times 50\text{px}$).
5. Optional Visual Gaps: Add a Grid Layout Group component to InventoryBoard with a cell size of 50x50 and populate it with 16 square images to represent background tiles. Crucial: Disable or remove the Grid Layout Group component once the layout looks right so it doesn't hijack the manual script anchoring.

2. Designing an Item Shape Asset

Thanks to the Custom Editor, you can draw your shape profiles visually:

1. In your project files, right-click and choose Create > Inventory > Item Shape. Name it Shape_Pistol.
2. Select the asset. In the Inspector, define your outer boundaries:
   • Bounding Width: 3
   • Bounding Height: 2
3. Click the interactive checkbox grid to model your shape footprint:

   [ ✅ ] [ ✅ ] [ ✅ ]  <-- Top barrel line (1, 1, 1)
   [ ✅ ] [ 🔲 ] [ 🔲 ]  <-- Lower grip line   (1, 0, 0)
   
   

3. Creating a Draggable UI Item Component

To keep the structural bounding calculations upright while letting your graphic animations spin freely, use a decoupled parent-child hierarchy layout:

1. Right-click outside the board and select UI > Image. Rename it to your item name (e.g., Item_Pistol).

2. Remove the Image component from this root parent object.

3. Attach the DraggableItem component and a Canvas Group component to this object.

4. Right-click your new item object and select UI > Image to create a nested child object. Name it VisualSprite.

   • Apply your actual texture/sprite artwork here.

   • Set its anchor configurations to Stretch / Stretch (Left: 0, Right: 0, Top: 0, Bottom: 0).

5. Head back to the parent item inspector:

   • Drag your custom scriptable asset (Shape_Pistol) into the Shape Data field.

   • Drag your child VisualSprite object into the Visual Sprite Element slot.

🎮 How It Functions In-Game

• Drag & Drop: Pick up items with Left-Click. The system handles raycast sampling from the item's true upper-left corner bounding region. It automatically snaps directly into position upon grid clearance.

• Responsive Rotation: Tap Right-Click while dragging to instantly shift the orientation. The logic maps structural boundary swaps while visually spinning the child sprite element, keeping the data layer completely aligned.

• Puzzle Check Validation: Hook your UI Level Progression buttons to verify the board array parameters. If any single slot reads false (empty space), progression stays locked!