Image.fillAmount

설명

Amount of the Image shown when the Image.type is set to Image.Type.Filled.

0-1 range with 0 being nothing shown, and 1 being the full Image.

using UnityEngine;
using System.Collections;
using UnityEngine.UI; // Required when Using UI elements.

public class Cooldown : MonoBehaviour {
	
	public Image cooldown;
	public bool coolingDown;
	public float waitTime = 30.0f;

	// Update is called once per frame
	void Update () 
	{
		if (coolingDown == true)
		{
			//Reduce fill amount over 30 seconds
			cooldown.fillAmount -= 1.0f/waitTime * Time.deltaTime;
		}
	}
}