Main/Assets/Plugins/Code/Cinematic/Effect/CinematicFadeBlack.cs

using UnityEngine;
using System.Collections;

namespace Thousandto.Cinematic
{
    /// <summary>
    /// 屏幕渐黑渐变
    /// </summary>
    public class CinematicFadeBlack : MonoBehaviour
    {
        //-------------------变量声明部分-------------------  
        #region Variables  
        public Shader CurShader;//着色器实例  
        private Material CurMaterial;//当前的材质  

        //shader需要的参数 [0, 1]
        private float Intensity = 1;

        //外部控制变量
        private float _speed = 1;
        private float _halfDuration = 0f;
        private Status _status;

        public float Duration = 2.0f;
        public float Strength = 0.5f;

        public bool Enable = false;
        #endregion


        //-------------------------材质的get&set----------------------------  
        #region MaterialGetAndSet  
        Material material
        {
            get
            {
                if (CurMaterial == null)
                {
                    CurMaterial = new Material(CurShader);
                    CurMaterial.hideFlags = HideFlags.HideAndDontSave;
                }
                return CurMaterial;
            }
        }
        #endregion

        //-----------------------------------------【Start()函数】---------------------------------------------    
        // 说明：此函数仅在Update函数第一次被调用前被调用  
        //--------------------------------------------------------------------------------------------------------  
        void Start()
        {
            //找到当前的Shader文件  
            CurShader = Shader.Find("Funcell/Cinematic/CinematicBlackBoard");
        }

        //-------------------------------------【OnRenderImage()函数】------------------------------------    
        // 说明：此函数在当完成所有渲染图片后被调用，用来渲染图片后期效果  
        //--------------------------------------------------------------------------------------------------------  
        void OnRenderImage(RenderTexture sourceTexture, RenderTexture destTexture)
        {
            //着色器实例不为空，就进行参数设置  
            if (CurShader != null)
            {
                //设置Shader中的外部变量  
                material.SetFloat("_BlackRate", Intensity);

                //拷贝源纹理到目标渲染纹理，加上我们的材质效果  
                Graphics.Blit(sourceTexture, destTexture, material);
            }
            //着色器实例为空，直接拷贝屏幕上的效果。此情况下是没有实现屏幕特效的  
            else
            {
                //直接拷贝源纹理到目标渲染纹理  
                Graphics.Blit(sourceTexture, destTexture);
            }

        }

        //-----------------------------------------【Update()函数】------------------------------------------    
        // 说明：此函数在每一帧中都会被调用  
        //--------------------------------------------------------------------------------------------------------   
        void Update()
        {
            if (!Enable) return;

            var timeDelta = Time.deltaTime;
            switch (_status)
            {
                case Status.ToBlack:
                    Intensity -= timeDelta * _speed;
                    if(Intensity <= 0)
                    {
                        Intensity = 0;
                        _status = Status.Duration;
                    }
                    break;
                case Status.Duration:
                    Duration -= timeDelta;
                    if(Duration <= 0)
                    {
                        Duration = 0;
                        _status = Status.ToWhite;
                    }
                    break;
                case Status.ToWhite:
                    Intensity += timeDelta * _speed;
                    if(Intensity >= 1)
                    {
                        Intensity = 1;
                        _status = Status.Finish;
                    }
                    break;
                case Status.Finish:
                    Duration = 0;
                    enabled = false;
                    Enable = false;
                    break;
            }
        }


        //-----------------------------------------【OnDisable()函数】---------------------------------------    
        // 说明：当对象变为不可用或非激活状态时此函数便被调用    
        //--------------------------------------------------------------------------------------------------------  
        void OnDisable()
        {
            if (CurMaterial)
            {
                enabled = false;
            }
        }

        /// <summary>
        /// 开始变换
        /// </summary>
        /// <param name="duration">变换持续时间</param>
        /// <param name="transDuration"></param>
        public void StartTrans(float duration = 1)
        {
            Intensity = 1;
            Duration = duration;
            Enable = true;
            enabled = true;
            _status = Status.ToBlack;
        }

        private enum Status
        {
            ToBlack,        //渐黑
            Duration,       //持续时间
            ToWhite,        //渐白
            Finish,         //完成
        }
    }

}