GridFinal.cs

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

public class Grid : MonoBehaviour {

    //* -> Assigned in Inspector
    public Transform CellPrefab;//*
    public Vector3 GridSize;//*
    public float Buffer;//*

    public List<Transform> Set = new List<Transform>();
    public List<Transform> CompletedSet = new List<Transform>();

    void Start ()
    {
        //CreateGrid ();
    }
    Transform[,]GridArr;
    public void CreateGrid ()
    {
        int x = (int)GridSize.x;
        int z = (int)GridSize.z;
        int maxXZ = Mathf.Max (x, z);
        Camera.mainCamera.transform.position = new Vector3 (maxXZ / 2f, maxXZ, maxXZ / 8f);
        GridArr = new Transform[x, z];
        Transform newCell;
        for (int ix = 0; ix < x; ix++) {
            for (int iz = 0; iz < z; iz++) {
                newCell = (Transform)Instantiate (CellPrefab, new Vector3 (ix, 0, iz) * Buffer, Quaternion.identity);
                newCell.name = string.Format ("({0},0,{1})", ix, iz);
                newCell.parent = transform;
                newCell.GetComponent<Cell> ().Position = new Vector3 (ix, 0, iz);
                GridArr [ix, iz] = newCell;
            }
        }
    }
    void SetStart (int x, int z)
    {
        AddToSet(GridArr[x,z]);
    }
    // n is 'Next'
    void AddToSet (Transform n)
    {
        Set.Insert (0, n);//Recursive
        //Set.Insert (Random.Range (0, Set.Count), n);//Prims
        Cell nScript = n.GetComponent<Cell> ();
        nScript.IsOpened = true;
        n.renderer.material.color = Color.grey;
    }

    public List<Vector3> Directions; //*
    void FindNext ()
    {

        if (Set.Count == 0) {
            Debug.Log ("We're done! Took " + Time.timeSinceLevelLoad + " seconds for a " + GridSize.x + " by " + GridSize.z + " grid.");
            CancelInvoke("FindNext");
            return;
        }

        Transform previous = Set [0];
        Cell pScript = Set [0].GetComponent<Cell> ();

        Transform next;
        Cell nScript;

        int prevX = (int)pScript.Position.x;
        int prevZ = (int)pScript.Position.z;

        int randSeed = Random.Range (0, 4);
        int counter = 0;

        int nextX;
        int nextZ;


        do {
            do {
                Vector3 randDirection = Directions [randSeed];
                nextX = prevX + (int)randDirection.x;
                nextZ = prevZ + (int)randDirection.z;
                randSeed = (randSeed + 1) % 4;
                counter++;
                if (counter > 4) {
                    AddToCompletedSet (previous);
                    return;
                }
            } while(nextX < 0 || nextZ < 0 || nextX >= GridSize.x || nextZ >= GridSize.z);
            next = GridArr [nextX, nextZ];
            nScript = next.GetComponent <Cell> ();
        } while(nScript.IsOpened);

        DrawDebugLines (10, previous, next);

        ClearWalls (previous, next);

        AddToSet (next);

    }

    void AddToCompletedSet (Transform  toAdd)
    {
        Set.Remove (toAdd);
        CompletedSet.Add (toAdd);
        toAdd.renderer.material.color = Color.black;

    }

    // p is 'Previous'
    // n is 'Next'
    void DrawDebugLines (int lines, Transform p, Transform n)
    {
        for (int i = 0; i < lines; i++) {
            Debug.DrawLine (p.position, n.position, Color.red, 100f);
        }
    }

    // p is 'Previous'
    // n is 'Next'
    void ClearWalls(Transform p, Transform n)
    {
        RaycastHit[] hitInfo;
        hitInfo = Physics.RaycastAll (p.position + Vector3.up, n.position - p.position, Buffer);
        foreach (RaycastHit hit in hitInfo) {
            Destroy (hit.transform.gameObject);
        }
    }
    void Update ()
    {
        if (Input.GetKeyDown (KeyCode.Tab) || Input.GetKey (KeyCode.Space)) {
            InvokeRepeating("FindNext", 0, 0.001f);//FindNext ();
        }
        if (Input.GetKeyDown (KeyCode.LeftShift)) {
            FindNext();
        }
        if(Input.GetKeyDown(KeyCode.F1))
        {
            Application.LoadLevel(0);
        }
    }
    bool start = true;
    void OnGUI()
    {
        GUILayout.Label("[Space] to create maze, \n[Shift] to step through maze, \n[F1] to restart");
        if(!start)
        {
            return;
        }
        GUILayout.BeginArea(new Rect(Screen.width/2f-100, Screen.height/2f, 200, 500));
        if(GUILayout.Button("10 x 3", GUILayout.Width(100), GUILayout.Height(30)))
        {
            GridSize = new Vector3(3,0,10);
            start = false;
            CreateGrid();
            SetStart (0, 0);
        }
        if(GUILayout.Button(" 9 x 4", GUILayout.Width(100), GUILayout.Height(30)))
        {
            GridSize = new Vector3(4,0,9);
            start = false;
            CreateGrid();
            SetStart (0, 0);
        }
        if(GUILayout.Button("10 x 10", GUILayout.Width(100), GUILayout.Height(30)))
        {
            GridSize = new Vector3(10,0,10);
            start = false;
            CreateGrid();
            SetStart (0, 0);
        }
        if(GUILayout.Button("25 x 25", GUILayout.Width(100), GUILayout.Height(30)))
        {
            GridSize = new Vector3(25,0,25);
            start = false;
            CreateGrid();
            SetStart (0, 0);
        }
        GUILayout.EndArea();
    }

}