Dynamically adding tiles to a grid based map - unity3d

Question

I want to have an infinitely explorable map. The plan is to create categories of game tiles (roads, obstacles, buildings), and randomly choose a category of game tile to be added when the player approaches the edge of the existing set of tiles. Tiles will also be destroyed once the player is 2 grid squares away from that tile. Currently I am using a multidimensional array that requires a size initializer.
What I have so far:
public class GameManager : MonoBehaviour
{
private GameObject[,] tileArray;
public GameObject groundTile;
public GameObject player;
private int tileSize = 80;
private int nextFarX = 1;
private int nextFarZ = 1;
private int nextNearX = -1;
private int nextNearZ = -1;
private float padding = .1f;
private int arrayOffset;
private int arrayDimension;
// Use this for initialization
void Start ()
{
arrayDimension = 200;
arrayOffset = arrayDimension / 2;
tileArray = new GameObject[,];
this.AddCubeAt(0, 0);
}
// Update is called once per frame
void Update () {
var x = Convert.ToInt32(player.transform.position.x / tileSize);
var z = Convert.ToInt32(player.transform.position.z / tileSize);
for (int i = -1; i < 2; i++)
{
for (int j = -1; j < 2; j++)
{
var checkX = x + i;
var checkZ = z + j;
if (tileArray[checkX + arrayOffset, checkZ + arrayOffset] == null)
{
//player is less than 2 tiles away from this grid, add a tile
this.AddCubeAt(checkX, checkZ);
}
}
}
// feels like a hack, but it will remove tiles that are not touching the tile that the player occupies
for (int i = 0; i < 6; i++)
{
for (int j = 0; j < 6; j++)
{
if (i == 0 | i == 5 | j == 0 | j == 5)
{
if (tileArray[x + (i-2) + arrayOffset, z + (j-2) + arrayOffset] != null)
{
Destroy(tileArray[x + (i - 2) + arrayOffset, z + (j - 2) + arrayOffset]);
tileArray[x + (i - 2) + arrayOffset, z + (j - 2) + arrayOffset] = null;
}
}
}
}
}
private void AddCubeAt(int x, int z)
{
var pos = new Vector3(x * tileSize, 0, z * tileSize);
var rot = Quaternion.identity;
GameObject newCube = (GameObject)Instantiate(groundTile, pos, rot);
tileArray[x + arrayOffset, z + arrayOffset] = newCube;
}
}
What is a better way to approach this?

Answer 1

You should familiarize yourself with Graph Data Structure (not adjacency matrix implementation). It's much more appropriate for this task. And, I would solve this
Tiles will also be destroyed once the player is 2 grid squares away from that tile
in another way: Every time player changed his position I would start DFS on target depth (in your case it's 2) and remove found tiles.

Answer 2

Decided to go with a simple Dictionary and methods to query/update it:
private GameObject RetrieveTileAt(int x, int z)
{
string key = string.Format("{0}.{1}", x, z);
if (tileDictionary.ContainsKey(key))
{
return tileDictionary[key];
}
else
{
return null;
}
}
private void InsertTileAt(int x, int z, GameObject tile)
{
string key = string.Format("{0}.{1}", x, z);
tileDictionary[key] = tile;
}
It is not an infinitely sized grid, (int min + int max)squared, but it should be far more than I need.