add grid manager

Assets/Scripts/GridBuildingSystem/GridBuildingSystem.cs

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+using UnityEngine;
+
+public class GridBuildingSystem : MonoBehaviour
+{
+    [SerializeField] private Transform _testTransform;
+    private GridXZ<GridObject> _grid;
+    private void Awake()
+    {
+        int gridWidth = 10;
+        int gridHeight = 10;
+        float cellSize = 10f;
+
+        _grid = new GridXZ<GridObject>(gridWidth, gridHeight, cellSize, Vector3.zero, (GridXZ<GridObject> g, int x, int z) => new GridObject(g, x, z));
+    }
+
+    private void Update()
+    {
+        if (Input.GetMouseButtonDown(0))
+        {
+            _grid.GetXZ(Mouse3d.GetMouseWorldPosition(), out int x, out int z);
+            var gridObject = _grid.GetGridObject(x, z);
+            if (gridObject.CanPlace())
+            {
+                var transform = Instantiate(_testTransform, _grid.GetWorldPosition(x, z), Quaternion.identity);
+                gridObject.SetTransform(transform);
+            }
+            else
+            {
+                Debug.Log("Can't place item here !!!");
+            }
+        }
+    }
+}

Assets/Scripts/GridBuildingSystem/GridBuildingSystem.cs.meta

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Assets/Scripts/GridBuildingSystem/GridObject.cs

@@ -0,0 +1,41 @@
+using UnityEngine;
+
+public class GridObject
+{
+    private GridXZ<GridObject> _grid;
+    private int _x;
+    private int _z;
+    private Transform _transform;
+
+
+    public GridObject(GridXZ<GridObject> grid, int x, int z)
+    {
+        _grid = grid;
+        _x = x;
+        _z = z;
+    }
+
+    public void SetTransform(Transform transform)
+    {
+        _transform = transform;
+        _grid.TriggerGridObjectChanged(_x, _z);
+    }
+
+    public void ClearTransform()
+    {
+        _transform = null;
+        _grid.TriggerGridObjectChanged(_x, _z);
+    }
+
+    public bool CanPlace()
+    {
+        return _transform == null;
+    }
+
+    public override string ToString()
+    {
+        return _x + "," + _z;
+    }
+}
+
+

Assets/Scripts/GridBuildingSystem/GridObject.cs.meta

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Assets/Scripts/GridBuildingSystem/GridXZ.cs

@@ -0,0 +1,145 @@
+/* 
+    ------------------- Code Monkey -------------------
+
+    Thank you for downloading this package
+    I hope you find it useful in your projects
+    If you have any questions let me know
+    Cheers!
+
+               unitycodemonkey.com
+    --------------------------------------------------
+ */
+
+using System;
+using UnityEngine;
+
+public class GridXZ<TGridObject>
+{
+
+    public event EventHandler<OnGridObjectChangedEventArgs> OnGridObjectChanged;
+    public class OnGridObjectChangedEventArgs : EventArgs
+    {
+        public int x;
+        public int z;
+    }
+
+    private int width;
+    private int height;
+    private float cellSize;
+    private Vector3 originPosition;
+    private TGridObject[,] gridArray;
+
+    public GridXZ(int width, int height, float cellSize, Vector3 originPosition, Func<GridXZ<TGridObject>, int, int, TGridObject> createGridObject)
+    {
+        this.width = width;
+        this.height = height;
+        this.cellSize = cellSize;
+        this.originPosition = originPosition;
+
+        gridArray = new TGridObject[width, height];
+
+        for (int x = 0; x < gridArray.GetLength(0); x++)
+        {
+            for (int z = 0; z < gridArray.GetLength(1); z++)
+            {
+                gridArray[x, z] = createGridObject(this, x, z);
+            }
+        }
+
+        bool showDebug = true;
+        if (showDebug)
+        {
+            TextMesh[,] debugTextArray = new TextMesh[width, height];
+
+            for (int x = 0; x < gridArray.GetLength(0); x++)
+            {
+                for (int z = 0; z < gridArray.GetLength(1); z++)
+                {
+                    Debug.DrawLine(GetWorldPosition(x, z), GetWorldPosition(x, z + 1), Color.white, 100f);
+                    Debug.DrawLine(GetWorldPosition(x, z), GetWorldPosition(x + 1, z), Color.white, 100f);
+                }
+            }
+            Debug.DrawLine(GetWorldPosition(0, height), GetWorldPosition(width, height), Color.white, 100f);
+            Debug.DrawLine(GetWorldPosition(width, 0), GetWorldPosition(width, height), Color.white, 100f);
+
+            OnGridObjectChanged += (object sender, OnGridObjectChangedEventArgs eventArgs) =>
+            {
+                debugTextArray[eventArgs.x, eventArgs.z].text = gridArray[eventArgs.x, eventArgs.z]?.ToString();
+            };
+        }
+    }
+
+    public int GetWidth()
+    {
+        return width;
+    }
+
+    public int GetHeight()
+    {
+        return height;
+    }
+
+    public float GetCellSize()
+    {
+        return cellSize;
+    }
+
+    public Vector3 GetWorldPosition(int x, int z)
+    {
+        return new Vector3(x, 0, z) * cellSize + originPosition;
+    }
+
+    public void GetXZ(Vector3 worldPosition, out int x, out int z)
+    {
+        x = Mathf.FloorToInt((worldPosition - originPosition).x / cellSize);
+        z = Mathf.FloorToInt((worldPosition - originPosition).z / cellSize);
+    }
+
+    public void SetGridObject(int x, int z, TGridObject value)
+    {
+        if (x >= 0 && z >= 0 && x < width && z < height)
+        {
+            gridArray[x, z] = value;
+            TriggerGridObjectChanged(x, z);
+        }
+    }
+
+    public void TriggerGridObjectChanged(int x, int z)
+    {
+        OnGridObjectChanged?.Invoke(this, new OnGridObjectChangedEventArgs { x = x, z = z });
+    }
+
+    public void SetGridObject(Vector3 worldPosition, TGridObject value)
+    {
+        GetXZ(worldPosition, out int x, out int z);
+        SetGridObject(x, z, value);
+    }
+
+    public TGridObject GetGridObject(int x, int z)
+    {
+        if (x >= 0 && z >= 0 && x < width && z < height)
+        {
+            return gridArray[x, z];
+        }
+        else
+        {
+            return default(TGridObject);
+        }
+    }
+
+    public TGridObject GetGridObject(Vector3 worldPosition)
+    {
+        int x, z;
+        GetXZ(worldPosition, out x, out z);
+        return GetGridObject(x, z);
+    }
+
+    public Vector2Int ValidateGridPosition(Vector2Int gridPosition)
+    {
+        return new Vector2Int(
+            Mathf.Clamp(gridPosition.x, 0, width - 1),
+            Mathf.Clamp(gridPosition.y, 0, height - 1)
+        );
+    }
+
+}

Assets/Scripts/GridBuildingSystem/GridXZ.cs.meta

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Assets/Scripts/GridBuildingSystem/Mouse3d.cs

@@ -0,0 +1,33 @@
+using UnityEngine;
+
+public class Mouse3d : MonoBehaviour
+{
+    public static Mouse3d Instance { get; private set; }
+    [SerializeField] private LayerMask _mouseColliderLayerMask = new LayerMask();
+
+    private void Awake()
+    {
+        Instance = this;
+        _mouseColliderLayerMask = transform.gameObject.layer;
+    }
+    private void Update()
+    {
+        Ray ray = Camera.main.ScreenPointToRay(Input.mousePosition);
+        if (Physics.Raycast(ray, out RaycastHit hit, 999f, _mouseColliderLayerMask))
+        {
+            transform.position = hit.point;
+        }
+    }
+    public static Vector3 GetMouseWorldPosition() => Instance.GetMouseWorldPosition_Instance();
+    private Vector3 GetMouseWorldPosition_Instance()
+    {
+        var ray = Camera.main.ScreenPointToRay(Input.mousePosition);
+        if (Physics.Raycast(ray, out RaycastHit hit, 999f, _mouseColliderLayerMask))
+        {
+            return hit.point;
+        }
+        return Vector3.zero;
+    }
+}
+
+

Assets/Scripts/GridBuildingSystem/Mouse3d.cs.meta

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