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

public class reflection : MonoBehaviour
{
    public Camera _mainCamera;
    public Camera _reflectionCamera;
    RenderTexture _reflectionRenderTexture;
    public  Transform _planner;

    private Material _palnnerMaterial;



    // Start is called before the first frame update
    void Start()
    {
        //拿到平面材质
        _palnnerMaterial = _planner.GetComponent<MeshRenderer>().material;
        //创建相机并指定相机渲染目标
        _reflectionRenderTexture = new RenderTexture(Screen.width, Screen.height, 24);
        _reflectionCamera.targetTexture = _reflectionRenderTexture;
        _reflectionCamera.enabled = true;
        //将相机渲染的目标赋给材质
        _palnnerMaterial.SetTexture("_ReflectionTex",_reflectionRenderTexture);
    }

    // Update is called once per frame
    void Update()
    {
        CalcReflectionCameraProperties();
    }

    void CalcReflectionCameraProperties()
    {
        Vector3 cameraPosWorldSpace = _mainCamera.transform.position;
        Vector3 cameraForwardWorldSpace = _mainCamera.transform.forward;
        Vector3 cameraUpDirWorldSpace = _mainCamera.transform.up;
        //转换世界坐标系的点到平面的局部坐标系下

        cameraPosWorldSpace.y *= -1.0f;
        cameraForwardWorldSpace.y *= -1.0f;
        //Vector3 cameraPosPlanarSpace = cameraPosWorldSpace; //_planner.InverseTransformPoint(cameraPosWorldSpace);
        //Vector3 cameraForwardPlannarSpace = _planner.InverseTransformPoint(cameraForwardWorldSpace);
        Vector3 cameraUpPlannarSpace=_planner.InverseTransformPoint(cameraUpDirWorldSpace);

        //cameraPosPlanarSpace.y *= -1.0f;
        //cameraForwardPlannarSpace.y *= -1.0f;
        cameraUpPlannarSpace.y *= -1.0f;

        //cameraPosWorldSpace = _planner.TransformPoint(cameraPosPlanarSpace);
        //cameraForwardWorldSpace = _planner.TransformPoint(cameraForwardPlannarSpace);
        cameraUpDirWorldSpace = _planner.TransformPoint(cameraUpPlannarSpace);

        _reflectionCamera.transform.position = cameraPosWorldSpace;
        _reflectionCamera.transform.LookAt(cameraPosWorldSpace+cameraForwardWorldSpace*0.1f,cameraUpDirWorldSpace);


    }

    private void OnDestroy()
    {
        
    }
}