unity3d 随机范围内生成怪物

using UnityEngine;
using System.Collections;

public class BarrackManager : MonoBehaviour {
public Transform[] address;
public GameObject[] prefabs;

// Use this for initialization
void Start () {
InvokeRepeating ("setBarrack",1,3f);
}

// Update is called once per frame
void Update () {

}

void setBarrack(){
Transform tf = address [Random.Range (0, address.Length)];
Bound bound = getBound (tf);
Vector3 pos = new Vector3 (bound.getRandomX(),bound.y,bound.getRandomZ());
Instantiate (prefabs[0],pos,Quaternion.identity);
}

Bound getBound(Transform tf){
Vector3 center = tf.collider.bounds.center;
Vector3 extents = tf.collider.bounds.extents;
Vector3 dL = new Vector3 (center.x - extents.x,center.y,center.z - extents.z);
Vector3 dR = new Vector3 (center.x + extents.x,center.y,center.z - extents.z);
Vector3 sR = new Vector3 (center.x + extents.x,center.y,center.z + extents.z);
Vector3 sL = new Vector3 (center.x - extents.x,center.y,center.z + extents.z);
Bound bound = new Bound (dL,dR,sR,sL,center.y);

return bound;
}

class Bound{
public Vector3 dL;
public Vector3 dR;
public Vector3 sR;
public Vector3 sL;
public float y;

public Bound(Vector3 dL,Vector3 dR, Vector3 sR, Vector3 sL,float y){
this.dL = dL;
this.dR = dR;
this.sR = sR;
this.sL = sL;
this.y = y;
}

public float getRandomX(){
float num = Random.Range (dL.x,dR.x);
return num;
}

public float getRandomZ(){
float num = Random.Range (dL.z,sL.z);
return num;
}

}

}