void Update()
        {
#if UNITY_EDITOR
            if (Application.isEditor && !Application.isPlaying && Preview == null)
            {
                Preview = new TerrainPreview();
            }
#endif
            if (Application.isPlaying && Pool != null && GenerateOnStart)
            {
                Pool.Update();
            }
        }
 void Awake()
 {
     Pool    = new TilePool();
     Preview = new TerrainPreview();
 }