untitled-game/Assets/Editor/Inventory/InventoryItemEditor.cs

using UnityEditor;
using UnityEngine;

[CustomEditor(typeof(InventoryItem))]
public class InventoryItemEditor : Editor
{
    private InventoryItem item;

    private void OnEnable()
    {
        item = (InventoryItem)target;
    }

    public override void OnInspectorGUI()
    {
        DrawDefaultInspector();

        GUILayout.Space(10);

        GUILayout.Label("Item Shape", EditorStyles.boldLabel);

        DrawGrid();
    }

    private void DrawGrid()
    {
        float size = 30f;

        for (int y = item.gridY - 1; y >= 0; y--)
        {
            GUILayout.BeginHorizontal();

            for (int x = 0; x < item.gridX; x++)
            {
                bool occupied = item.IsOccupied(x, y);

                GUI.backgroundColor = occupied ? Color.yellow : Color.gray;

                if (GUILayout.Button("", GUILayout.Width(size), GUILayout.Height(size)))
                {
                    Undo.RecordObject(item, "Toggle Item Cell");

                    item.SetOccupied(x, y, !occupied);

                    EditorUtility.SetDirty(item);
                }
            }

            GUILayout.EndHorizontal();
        }

        GUI.backgroundColor = Color.white;
    }

    private void OnSceneGUI()
    {
        SpriteRenderer sr = item.GetComponent<SpriteRenderer>();

        if (sr == null || sr.sprite == null)
        {
            return;
        }

        Bounds bounds = sr.bounds;

        float cellWidth = bounds.size.x / item.gridX;
        float cellHeight = bounds.size.y / item.gridY;

        Handles.color = Color.cyan;

        // Draw cells
        for (int x = 0; x < item.gridX; x++)
        {
            for (int y = 0; y < item.gridY; y++)
            {
                float left = bounds.min.x + x * cellWidth;
                float bottom = bounds.min.y + y * cellHeight;

                Rect cell = new Rect(
                    left,
                    bottom,
                    cellWidth,
                    cellHeight
                );

                // Draw occupied cells
                if (item.IsOccupied(x, y))
                {
                    Handles.DrawSolidRectangleWithOutline(
                        cell,
                        new Color(1, 0.8f, 0, 0.35f),
                        Color.yellow
                    );
                }

                // Draw label
                Handles.Label(
                    new Vector3(
                        left + cellWidth / 2,
                        bottom + cellHeight / 2,
                        0),
                    $"{x},{y}"
                );
            }
        }

        // Draw grid lines
        Handles.color = Color.cyan;

        for (int x = 0; x <= item.gridX; x++)
        {
            float xPos = bounds.min.x + x * cellWidth;
            Handles.DrawLine(
                new Vector3(xPos, bounds.min.y),
                new Vector3(xPos, bounds.max.y));
        }

        for (int y = 0; y <= item.gridY; y++)
        {
            float yPos = bounds.min.y + y * cellHeight;
            Handles.DrawLine(
                new Vector3(bounds.min.x, yPos),
                new Vector3(bounds.max.x, yPos));
        }

        // Handle clicks
        Event e = Event.current;

        if (e.type == EventType.MouseDown && e.button == 0)
        {
            Vector3 mouseWorld = HandleUtility.GUIPointToWorldRay(e.mousePosition).origin;

            int x = Mathf.FloorToInt((mouseWorld.x - bounds.min.x) / cellWidth);

            int y = Mathf.FloorToInt((mouseWorld.y - bounds.min.y) / cellHeight);

            if (x >= 0 && x < item.gridX
                && y >= 0 && y < item.gridY)
            {
                Undo.RecordObject(item, "Toggle Item Cell");

                item.SetOccupied(x, y, !item.IsOccupied(x, y));

                EditorUtility.SetDirty(item);

                e.Use();
            }
        }
    }
}