Grid

using System.Collections;
using System.Collections.Generic;
using UnityEngine;

public class NavGrid : MonoBehaviour {

    public Vector2 size;
    public float nodeSize = 1;
    public LayerMask collisionMask;
    public float height = 10;
    public Transform test;

    Node[,] debugNodes;

    [ContextMenu("Gen nodes")]
    public Node[,] GenerateNodes()
    {
        Vector2Int numNodes = NumNodes;
        Node[,] nodes = new Node[numNodes.x,numNodes.y];

       // Vector3 rayTopLeft = new Vector3(-nodeSize * numNodes.x / 2f, height, nodeSize * numNodes.y / 2f);

        for (int y = 0; y < numNodes.y; y++)
        {
            for (int x = 0; x < numNodes.x; x++)
            {
                Vector3 rayPos = WorldPosCentreOfCoordinate(x, y) + Vector3.up * height;
                RaycastHit hit;

                Vector3 nodePosition = new Vector3(rayPos.x, 0, rayPos.z);
                bool nodeIsTraversable = false;

                if (Physics.Raycast(rayPos, Vector3.down, out hit, height * 2, collisionMask))
                {
                    nodePosition = hit.point;

                    if (hit.collider.tag == "Ground")
                    {
                        nodeIsTraversable = true;
                    }
                }
                nodes[x, y] = new Node(nodeIsTraversable, nodePosition, new Vector2Int(x,y));

            }
        }
        debugNodes = nodes;
        return nodes;
    }

    public Vector3 WorldPosCentreOfCoordinate(int x, int y)
    {
        Vector3 topLeft = new Vector3(-nodeSize * (NumNodes.x-1) / 2f,0, nodeSize * (NumNodes.y-1) / 2f);
        return topLeft + (Vector3.right * x + Vector3.back * y) * nodeSize;
    }

    public Vector2Int CoordinateFromWorldPos(Vector3 pos)
    {
        int x = Mathf.RoundToInt((pos.x) / nodeSize + (NumNodes.x - 1) * .5f);
        int y = Mathf.RoundToInt((-pos.z) / nodeSize + (NumNodes.y - 1) * .5f);
        return new Vector2Int(Mathf.Clamp(x, 0, NumNodes.x - 1), Mathf.Clamp(y, 0, NumNodes.y - 1));
    }

    Vector2Int NumNodes
    {
        get
        {
            return new Vector2Int(Mathf.RoundToInt(size.x / nodeSize), Mathf.RoundToInt(size.y / nodeSize));
        }
    }

    private void OnDrawGizmos()
    {
        Vector2Int coordFromWorldTest = CoordinateFromWorldPos(test.position);
        for (int y = 0; y < NumNodes.y; y++)
        {
            for (int x = 0; x < NumNodes.x; x++)
            {
                if (x == coordFromWorldTest.x && y == coordFromWorldTest.y)
                {
                    Gizmos.DrawCube(WorldPosCentreOfCoordinate(x, y) + Vector3.up * height, new Vector3(nodeSize, 0, nodeSize));
                }
                else
                {
                    Gizmos.DrawWireCube(WorldPosCentreOfCoordinate(x, y) + Vector3.up * height, new Vector3(nodeSize, 0, nodeSize));
                    if (debugNodes != null)
                    {
                        if (!debugNodes[x, y].isTraversable)
                        {
                            Gizmos.color = new Color(1, 0, 0, .5f);
                            Gizmos.DrawCube(WorldPosCentreOfCoordinate(x, y) + Vector3.up * height, new Vector3(nodeSize, 0, nodeSize));
                            Gizmos.color = Color.white;
                        }
                    }
                }
            }
        }
    }
}