using System.Collections;
using System.Collections.Generic;
using LuaInterface;
using UnityEngine;

[ExecuteInEditMode]
[RequireComponent(typeof(Camera))]
public class ScreenEffect : MonoBehaviour {
    private RenderTexture final_renderTexture; // 最终渲染出来的画面RT缓存

    #region 高速模糊相关参数
    private const int BLUR_PASS_HOR = 0; // 水平模糊pass
    private const int BLUR_PASS_VER = 1; // 垂直模糊pass
    public Material blurMaterial;   // 高速模糊材质
    [HideInInspector]
    public bool render_blur_effect = false;   // 高斯模糊关键参数，设置为true时会开始渲染高斯模糊纹理
    public bool get_screen_shot = false; // 与上面的功能区分，只截图，并不会改变原先的渲染
    // 高斯模糊缓存纹理（不要在渲染时动态创建，会消耗很多内存，这里先生成引用）
    private RenderTexture buffer_temp; // 临时材质
    public float blurSpread = 0.4f;  // 模糊散值
    public float blur_amount = 1f;  // 模糊插值，0:初始效果，1:完全模糊效果
    private int recurveNum = 1;     // 当前迭代的渲染次数
    public int recurveMaxNum = 1;   // 最大迭代渲染次数
    public int downSample = 4;  // 降低采样率比率(降低采样率可以提高性能，但肯定会让效果变差)
    LuaFunction screenshot_callback; // 模糊截图回调
    #endregion

    #region 双面模糊相关参数
    const int DOWN_SAMPLE_PASS = 0; // 降采样pass
    const int UP_SAMPLE_PASS = 1; // 升采样pass
    public bool use_dual_blur = false; // 使用双面模糊
    public Material dual_blur_mat; // 双面模糊材质球
    RenderTextureFormat format;
    #endregion
    private bool isSupported; // 设备支持变量
    private void Start()
    {
        isSupported = CheckSupport();
        this.enabled = false;
    }
    // 检测当前平台是否支持屏幕特效
    private bool CheckSupport()
    {
        if (SystemInfo.supportsImageEffects == false)
        {
            Debug.LogWarning("当前平台不支持！");
            return false;
        }
        return true;
    }
    // 获取设备支持
    public bool GetSupported()
    {
        return isSupported;
    }
    void OnRenderImage(RenderTexture src, RenderTexture dest)
    {
        format = src.format;
        //1.迭代渲染画面，加强模糊效果
        //当设置为了true时，获取当前的画面内容
        if (blurMaterial != null && dual_blur_mat != null && (render_blur_effect || get_screen_shot))
        {
            // 使用双面模糊算法
            if(use_dual_blur){
                int width = src.width;
                int height = src.height;
                recurveNum = 1; // 初始化迭代
                while(recurveNum <= recurveMaxNum)
                {
                    width /= downSample;
                    height /= downSample;
                    dual_blur_mat.SetFloat("_Offset", (1.0f + recurveNum * blurSpread) * blur_amount);  // 设置模糊扩散uv偏移
                    buffer_temp = RenderTexture.GetTemporary(width, height, 0, format);  
                    // 降采样渲染
                    if(recurveNum == 1)
                    {
                        Graphics.Blit(src, buffer_temp, dual_blur_mat, DOWN_SAMPLE_PASS);
                    }
                    else{
                        Graphics.Blit(final_renderTexture, buffer_temp, dual_blur_mat, DOWN_SAMPLE_PASS);
                    }
                    
                    // 升采样渲染
                    width *= downSample; 
                    height *= downSample; 
                    ReleaseTargetRenderTexture(final_renderTexture);
                    final_renderTexture = RenderTexture.GetTemporary(width, height, 0, format);
                    Graphics.Blit(buffer_temp, final_renderTexture, dual_blur_mat, UP_SAMPLE_PASS);
                    RenderTexture.ReleaseTemporary(buffer_temp);   // 释放临时RT
                    recurveNum ++;
                }
            }else
            {
                recurveNum = 1;
                //缩小要模糊的图片，减少处理压力
                int width = src.width / downSample;
                int height = src.height / downSample;
                final_renderTexture = RenderTexture.GetTemporary(width, height, 0);
                final_renderTexture.filterMode = FilterMode.Bilinear;
                Graphics.Blit(src, final_renderTexture);
                while(recurveNum <= recurveMaxNum){
                    recurveNum ++;
                    blurMaterial.SetFloat("_BlurSize", (1.0f + recurveNum * blurSpread) * blur_amount);  
                    buffer_temp = RenderTexture.GetTemporary(width, height, 0);  
                    Graphics.Blit(final_renderTexture, buffer_temp, blurMaterial, BLUR_PASS_HOR);  
                    Graphics.Blit(buffer_temp, final_renderTexture, blurMaterial, BLUR_PASS_VER);  
                    RenderTexture.ReleaseTemporary(buffer_temp);  
                }
            }
            
            if(get_screen_shot && !render_blur_effect){
                GetBlurScreenShot();
                Graphics.Blit(src, dest);
                get_screen_shot = false; // 截图生成之后就停止运作
                this.enabled = false;
            }
            else{
                Graphics.Blit(final_renderTexture, dest);
                RenderTexture.ReleaseTemporary(final_renderTexture); 
            }
        }
        else
        {
            Graphics.Blit(src, dest);
        }
    }
    // 设置开始处理模糊效果的截图
    public void RenderBlurScreenShot(float blur_amount, int downSample, LuaFunction func)
    {
        get_screen_shot = true;
        this.blur_amount = blur_amount;
        this.downSample = downSample;
        screenshot_callback = func;
    }
    void GetBlurScreenShot()
    {
        RenderTexture temp_screen_shot = RenderTexture.GetTemporary(final_renderTexture.width, final_renderTexture.height, 0);
        Graphics.Blit(final_renderTexture, temp_screen_shot);
        if (screenshot_callback != null)
        {
            List<UnityEngine.Object> list = new List<UnityEngine.Object>();
            list.Add(temp_screen_shot);
            object[] args = new object[] { list.ToArray() };
            screenshot_callback.Call(args);
            screenshot_callback.Dispose();
            screenshot_callback = null;
        }
        ReleaseRenderTexCache();
    }
    // 销毁渲染纹理缓存
    public void ReleaseRenderTexCache()
    {
        if (!render_blur_effect) {
            RenderTexture.ReleaseTemporary(final_renderTexture); 
        }
    }

    public void ReleaseTargetRenderTexture(RenderTexture rt)
    {
        if (rt!= null)
        {
            RenderTexture.ReleaseTemporary(rt); 
            rt = null;
        }
    }

}