using System.Collections;
using UnityEngine;

public class Glinting : MonoBehaviour
{
 /// <summary>
 /// 閃爍顏色
 /// </summary>
 public Color color = new Color(1, 0, 1, 1);
 /// <summary>
 /// 最低發(fā)光亮度，取值范圍[0,1]，需小于最高發(fā)光亮度。
 /// </summary>
 [Range(0.0f, 1.0f)]
 public float minBrightness = 0.0f;
 /// <summary>
 /// 最高發(fā)光亮度，取值范圍[0,1]，需大于最低發(fā)光亮度。
 /// </summary>
 [Range(0.0f, 1)]
 public float maxBrightness = 0.5f;
 /// <summary>
 /// 閃爍頻率，取值范圍[0.2,30.0]。
 /// </summary>
 [Range(0.2f, 30.0f)]
 public float rate = 1;

 [Tooltip("勾選此項則啟動時自動開始閃爍")]
 [SerializeField]
 private bool _autoStart = false;

 private float _h, _s, _v;  // 色調(diào)，飽和度，亮度
 private float _deltaBrightness; // 最低最高亮度差
 private Renderer _renderer;
 private Material _material;
 private readonly string _keyword = "_EMISSION";
 private readonly string _colorName = "_EmissionColor";

 private Coroutine _glinting;

 private void Start()
 {
 _renderer = gameObject.GetComponent<Renderer>();
 _material = _renderer.material;

 if (_autoStart)
 {
  StartGlinting();
 }
 }

 /// <summary>
 /// 校驗數(shù)據(jù)，并保證運行時的修改能夠得到應(yīng)用。
 /// 該方法只在編輯器模式中生效?。?！
 /// </summary>
 private void OnValidate()
 {
 // 限制亮度范圍
 if (minBrightness < 0 || minBrightness > 1)
 {
  minBrightness = 0.0f;
  Debug.LogError("最低亮度超出取值范圍[0, 1]，已重置為0。");
 }
 if (maxBrightness < 0 || maxBrightness > 1)
 {
  maxBrightness = 1.0f;
  Debug.LogError("最高亮度超出取值范圍[0, 1]，已重置為1。");
 }
 if (minBrightness >= maxBrightness)
 {
  minBrightness = 0.0f;
  maxBrightness = 1.0f;
  Debug.LogError("最低亮度[MinBrightness]必須低于最高亮度[MaxBrightness]，已分別重置為0/1！");
 }

 // 限制閃爍頻率
 if (rate < 0.2f || rate > 30.0f)
 {
  rate = 1;
  Debug.LogError("閃爍頻率超出取值范圍[0.2, 30.0]，已重置為1.0。");
 }

 // 更新亮度差
 _deltaBrightness = maxBrightness - minBrightness;

 // 更新顏色
 // 注意不能使用 _v ，否則在運行時修改參數(shù)會導(dǎo)致亮度突變
 float tempV = 0;
 Color.RGBToHSV(color, out _h, out _s, out tempV);
 }

 /// <summary>
 /// 開始閃爍。
 /// </summary>
 public void StartGlinting()
 {
 _material.EnableKeyword(_keyword);

 if (_glinting != null)
 {
  StopCoroutine(_glinting);
 }
 _glinting = StartCoroutine(IEGlinting());
 }

 /// <summary>
 /// 停止閃爍。
 /// </summary>
 public void StopGlinting()
 {
 _material.DisableKeyword(_keyword);

 if (_glinting != null)
 {
  StopCoroutine(_glinting);
 }
 }

 /// <summary>
 /// 控制自發(fā)光強度。
 /// </summary>
 /// <returns></returns>
 private IEnumerator IEGlinting()
 {
 Color.RGBToHSV(color, out _h, out _s, out _v);
 _v = minBrightness;
 _deltaBrightness = maxBrightness - minBrightness;

 bool increase = true;
 while (true)
 {
  if (increase)
  {
  _v += _deltaBrightness * Time.deltaTime * rate;
  increase = _v <= maxBrightness;
  }
  else
  {
  _v -= _deltaBrightness * Time.deltaTime * rate;
  increase = _v <= minBrightness;
  }
  _material.SetColor(_colorName, Color.HSVToRGB(_h, _s, _v));
  //_renderer.UpdateGIMaterials();
  yield return null;
 }
 }
}