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

public class MyBotBase : MonoBehaviour
{
    private int num = 0;

    // ★追加
    public Material[] myMaterials;
    public bool isSetOK;

    // ★追加
    private void Start()
    {
        GetComponent<MeshRenderer>().material = myMaterials[0];
        isSetOK = false;
    }

    void Update()
    {
        Vector3 pos = transform.position;

        if(Input.GetKeyDown(KeyCode.LeftArrow))
        {
            transform.position = new Vector3(pos.x - 1, 0, pos.z); 
        }
        if (Input.GetKeyDown(KeyCode.RightArrow))
        {
            transform.position = new Vector3(pos.x + 1, 0, pos.z);
        }
        if (Input.GetKeyDown(KeyCode.UpArrow))
        {
            transform.position = new Vector3(pos.x, 0, pos.z + 1);
        }
        if (Input.GetKeyDown(KeyCode.DownArrow))
        {
            transform.position = new Vector3(pos.x, 0, pos.z - 1);
        }

        if (Input.GetKeyDown(KeyCode.RightShift))
        {
            num += 1;
            transform.rotation = Quaternion.Euler(0, 90 * num, 0);
        }
    }

    // ★追加
    // （ポイント）
    // Trigger系のメソッドを使うので、Is Triggerにチェックが必要！！
    // 表示が切り替わらない場合には『MyBotBase』オブジェクトの『Box Collider』の『Is Trigger』にチェックが入っているか確認しよう！
    private void OnTriggerStay(Collider other)
    {
        if(other.gameObject.tag == "BlueTeritory")
        {
            GetComponent<MeshRenderer>().material = myMaterials[1];
            isSetOK = true;
        }
        else if(other.gameObject.tag == "RedTeritory")
        {
            GetComponent<MeshRenderer>().material = myMaterials[0];
            isSetOK = false;
        }
    }

    // ★追加
    private void OnTriggerExit(Collider other)
    {
        if (other.gameObject.tag == "BlueTeritory")
        {
            GetComponent<MeshRenderer>().material = myMaterials[0];
            isSetOK = false;
        }
    }
}
C#

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

public class MyBotSet : MonoBehaviour
{
    private int setCount;
    private Text countLabel;
    private int getGPpoint;
    private GPManager gpm;
    public int price;
    public GameObject myBotPrefab;
    private GameObject myBotBase;

    // ★追加
    private bool setOK;

    void Start()
    {
        setCount = 0;
        countLabel = GetComponent<Text>();
        countLabel.text = "×　" + setCount.ToString("D3");
        gpm = GameObject.Find("GPLabel").GetComponent<GPManager>();
        myBotBase = GameObject.Find("MyBotBase");
    }

    void Update()
    {
        getGPpoint = gpm.gpPoint;
        setCount = getGPpoint / price;
        countLabel.text = "×" + setCount.ToString("D3");

        // ★追加
        setOK = myBotBase.GetComponent<MyBotBase>().isSetOK;
}

    public void OnMyBotButtonClicked()
    {
        // ★追加（『&& setOK == true』を追加する）
        if (setCount > 0 && setOK == true)
        {
            Instantiate(myBotPrefab, myBotBase.transform.position, myBotBase.transform.rotation);
            gpm.ReduceGP(price);
        }
    }
}
C#