Unity 技能冷却条

using UnityEngine;
using UnityEngine.UI;
///<summary>
///技能冷却条
///</summary>
public class SkillItem : MonoBehaviour
{

    public float coldTime = 2f;
    private float timer = 0f;   //
    private Image filledImage;
    private bool isStartTimer; 
    // Start is called before the first frame update
    void Start()
    {
        filledImage = transform.Find("FilledSkill").GetComponent<Image>();
    }

    // Update is called once per frame
    void Update()
    {
        if(isStartTimer){
            timer += Time.deltaTime;
            filledImage.fillAmount = (coldTime-timer)/coldTime;
        }
        if(timer >= coldTime){
            filledImage.fillAmount = 0;
            timer = 0;
            isStartTimer = false;
        }
    }
    public void OoClick(){
        isStartTimer = true;
    }
}