GUIStatusMeter.cs

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

public class GUIStatusMeter : MonoBehaviour
{
    private static GUIStatusMeter _instance;

    public float EnergyBarEaseFactor;
    public float HeartScaleEaseFactor;
    public float HeartMinScale;
    public float HeartMaxScale;

    Image _energyBarFill;
    Transform _heartTransform;
    Character _character;
    Animator _heartAnim;

    int _isTargetHash = Animator.StringToHash("IsTarget");
    int _isExtremeHash = Animator.StringToHash("IsExtreme");

    public static void RegisterEnergyProvider(Character provider)
    {
        _instance._character = provider;
    }

    void Awake()
    {
        _instance = this;
        _energyBarFill = transform.FindChild("energy_bar/fill").GetComponent<Image>();
        _heartTransform = transform.FindChild("heart");
        _heartAnim = _heartTransform.GetComponent<Animator>();
    }

    void Start()
    {
        Heart.TierChanged += OnHeartTierChange;
    }

    void OnHeartTierChange(HeartTier newTier, HeartTier prevTier)
    {
        _heartAnim.SetBool(_isTargetHash, newTier == HeartTier.Target);
        _heartAnim.SetBool(_isExtremeHash, newTier == HeartTier.Extreme);
    }

    void Update()
    {
        if (_character != null)
        {
            _energyBarFill.fillAmount = Mathf.Lerp(_energyBarFill.fillAmount, _character.Energy, Time.deltaTime * EnergyBarEaseFactor);
            _energyBarFill.SetAllDirty();
        }
        else
            _energyBarFill.fillAmount = Mathf.Lerp(_energyBarFill.fillAmount, 0, Time.deltaTime * EnergyBarEaseFactor);

        _heartTransform.localScale = Vector3.Lerp(_heartTransform.localScale,
                                                Vector3.one * Mathf.Clamp(Heart.NormalizedRate, HeartMinScale, HeartMaxScale),
                                                Time.deltaTime * HeartScaleEaseFactor);
    }
}