using System;
using System.Collections;
using System.Collections.Generic;
using UnityEngine;
using UnityEngine.Rendering;
using UnityEngine.Rendering.Universal;
using UnityEngine.XR;

public class reflection : MonoBehaviour
{
    public Camera _mainCamera;
    public Camera _reflectionCamera_L;
    public Camera _reflectionCamera_R;
    public Material matBur;
    public  Transform _planner;

    private Material _palnnerMaterial;
    RenderTexture _reflectionRenderTexture_L;
    RenderTexture _reflectionRenderTexture_R;
    private int renderLeft=0;

    //private readonly int temp_L = Shader.PropertyToID("_reflectionRenderTexture_L");
    //private readonly int temp_R = Shader.PropertyToID("_reflectionRenderTexture_R");

    // Start is called before the first frame update
    void Start()
    {

        _reflectionCamera_L.CopyFrom(_mainCamera);
        _palnnerMaterial = _planner.GetComponent<MeshRenderer>().material;
        
        //创建相机并指定相机渲染目标
        _reflectionRenderTexture_L = new RenderTexture(Screen.width/4, Screen.height/4, 24);

        _reflectionCamera_L.targetTexture =  _reflectionRenderTexture_L;
        _reflectionRenderTexture_R = new RenderTexture(Screen.width/4, Screen.height/4, 24);
        
        
        _reflectionCamera_R.CopyFrom(_mainCamera);

        
        _reflectionCamera_R.targetTexture = _reflectionRenderTexture_R;
        //将相机渲染的目标赋给材质
        _palnnerMaterial.SetTexture("_ReflectionTex_R",_reflectionRenderTexture_R);
        _palnnerMaterial.SetTexture("_ReflectionTex_L",_reflectionRenderTexture_L);
        //将相机渲染的目标赋给材质
        RenderPipelineManager.beginCameraRendering += OnBeginCameraRendering;
    }

    private void OnBeginCameraRendering(ScriptableRenderContext arg1, Camera arg2)
    {
        if(arg2!=_mainCamera) return;
        var leftEyeM = _mainCamera.GetStereoViewMatrix(Camera.StereoscopicEye.Left);
        var leftEyePM=_mainCamera.GetStereoProjectionMatrix(Camera.StereoscopicEye.Left);
        
            
        _reflectionCamera_L.worldToCameraMatrix =leftEyeM * CalculateReflectionCameraMatrix(Vector3.up,  _planner.position);
        _reflectionCamera_L.projectionMatrix = leftEyePM;
        
        var rightEyeM = _mainCamera.GetStereoViewMatrix(Camera.StereoscopicEye.Right);
        var rightEyePM=_mainCamera.GetStereoProjectionMatrix(Camera.StereoscopicEye.Right);
       
            
        _reflectionCamera_R.worldToCameraMatrix =rightEyeM * CalculateReflectionCameraMatrix(Vector3.up,  _planner.position);
        _reflectionCamera_R.projectionMatrix = rightEyePM;
        
        GL.invertCulling = true;//进行裁剪顺序的翻转
        

        _palnnerMaterial.SetFloat("_renderEye",renderLeft);
        CommandBuffer cmd = CommandBufferPool.Get("ReflectionBur");
        matBur.SetFloat("_BurStength",1f);
        if (renderLeft==0)
        {
            UniversalRenderPipeline.RenderSingleCamera(arg1, _reflectionCamera_L);//摄像机开始渲染
            cmd.Blit(_reflectionRenderTexture_L,_reflectionRenderTexture_R,matBur,0);
            cmd.Blit(_reflectionRenderTexture_R,_reflectionRenderTexture_L,matBur,0);
            arg1.ExecuteCommandBuffer(cmd);
            renderLeft = 1;
        }
        else
        {
            UniversalRenderPipeline.RenderSingleCamera(arg1, _reflectionCamera_R);
            cmd.Blit(_reflectionRenderTexture_R,_reflectionRenderTexture_L,matBur,0);
            cmd.Blit(_reflectionRenderTexture_L,_reflectionRenderTexture_R,matBur,0);
            arg1.ExecuteCommandBuffer(cmd);
            renderLeft = 0;
        }
        cmd.Release();
        
        GL.invertCulling = false;//进行裁剪顺序的翻转
        
    }
    
    
    //计算反射矩阵R
    private Matrix4x4 CalculateReflectionCameraMatrix(Vector3 N, Vector3 plane_position)//计算返回反射矩阵
    {
        //下面计算反射矩阵是在世界空间计算的
        Matrix4x4 Reflection_camera_M = Matrix4x4.identity;//初始化反射矩阵
        //d指的是平面到世界坐标原点的距离
        float d = -Vector3.Dot(plane_position, N);//d = -dot(P, N),P是平面上的任意一点，N是平面的法向量
        
        Reflection_camera_M.m00 = 1 - 2 * N.x * N.x;
        Reflection_camera_M.m01 = - 2 * N.x * N.y;
        Reflection_camera_M.m02 = - 2 * N.x * N.z;
        Reflection_camera_M.m03 = - 2 * N.x * d;
        
        Reflection_camera_M.m10 = - 2 * N.x * N.y;
        Reflection_camera_M.m11 = 1 - 2 * N.y * N.y;
        Reflection_camera_M.m12 = - 2 * N.y * N.z;
        Reflection_camera_M.m13 = - 2 * N.y * d;
        
        Reflection_camera_M.m20 = - 2 * N.x * N.z;
        Reflection_camera_M.m21 = - 2 * N.y * N.z;
        Reflection_camera_M.m22 = 1 - 2 * N.z * N.z;
        Reflection_camera_M.m23 = - 2 * N.z * d;
        
        Reflection_camera_M.m30 = 0;
        Reflection_camera_M.m31 = 0;
        Reflection_camera_M.m32 = 0;
        Reflection_camera_M.m33 = 1;

        return Reflection_camera_M;
    } 
   

    private void OnDestroy()
    {
        RenderPipelineManager.beginCameraRendering -= OnBeginCameraRendering;
        _reflectionRenderTexture_L.Release();
        _reflectionRenderTexture_R.Release();
        _reflectionRenderTexture_L = null;
        _reflectionRenderTexture_R = null;
    }
}