using UnityEngine;
using System.Collections;

namespace Thousandto.Cinematic
{
    /// <summary>
    /// 相机运动模糊效果
    /// </summary>
    public class CinematicSportBlur : 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 [-0.5, 0.5]
        private float Intensity = 0;
        private float OffsetX = 0.5f;
        private float OffsetY = 0.5f;
        private Vector2 CenterV2;

        //外部控制变量
        private float _speed;
        private float _halfDuration;
        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()
        {
            CenterV2 = new Vector2(OffsetX, OffsetY);

            //找到当前的Shader文件  
            CurShader = Shader.Find("Funcell/Cinematic/CinematicSportBlur");

            //判断是否支持屏幕特效  
            if (!SystemInfo.supportsImageEffects)
            {
                enabled = false;
                return;
            }
        }

        //-------------------------------------【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("_Value", Intensity);
                material.SetVector("_Center", CenterV2);

                //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);
            }

        }


        //-----------------------------------------【OnValidate()函数】--------------------------------------    
        // 说明：此函数在编辑器中该脚本的某个值发生了改变后被调用  
        //--------------------------------------------------------------------------------------------------------  
        void OnValidate()
        {
            //将编辑器中的值赋值回来，确保在编辑器中值的改变立刻让结果生效  
            CenterV2 = new Vector2(OffsetX, OffsetY);
        }

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

            if(Duration > 0)
            {
                var timeDelta = Time.deltaTime;
                Duration -= timeDelta;
                if(Duration > _halfDuration)
                    Intensity += timeDelta * _speed;
                else
                    Intensity -= timeDelta * _speed;
            }
            else
            {
                Duration = 0;
                enabled = false;
                Enable = false;
            }
        }


        //-----------------------------------------【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;
            }
        }

        public void StartBlur(float duration, float strength = 0.5f)
        {
            Duration = duration;
            _halfDuration = duration / 2;
            _speed = strength / duration;
            Enable = true;
            enabled = true;
        }
    }

}