Unity Steam VR 摄像头画面镜像处理

让Steam VR的画面左右翻转， 而且物体不会发生变化。效果如下


网上找到的教程大多数都是这个：unity摄像机实现镜像效果
设置后虽然也镜像了，但是物体的阴影那些会发生变化，此代码不会。初学者我也不懂，貌似是对生成后的图像进行处理的。
Shader：

Shader "Custom/FrontCameraInvertImage" {
	Properties{
		_MainTex("Base (RGB)", 2D) = "" {}
		_AxisX("x or y", Range(0,1)) = 0 //0 for x; 1 for y
	}

		// Shader code pasted into all further CGPROGRAM blocks
			CGINCLUDE

#include "UnityCG.cginc"

			struct v2f {
			float4 pos : SV_POSITION;
			float2 uv : TEXCOORD0;
		};

		sampler2D _MainTex;
		half4 _MainTex_ST;

		float _AxisX;

		v2f vert(appdata_img v)
		{
			v2f o;
			o.pos = UnityObjectToClipPos(v.vertex);
			o.uv = v.texcoord.xy;
			return o;
		}

		half4 frag(v2f i) : SV_Target
		{
			if (_AxisX == 0)
				i.uv.x = 1 - i.uv.x;
			else
				i.uv.y = 1 - i.uv.y;

			half4 color = tex2D(_MainTex, UnityStereoScreenSpaceUVAdjust(i.uv, _MainTex_ST));

			return color;
		}

			ENDCG

			Subshader {
			Pass{
				ZTest Always Cull Off ZWrite Off

				CGPROGRAM
	#pragma vertex vert
	#pragma fragment frag
				ENDCG
			}

		}

		Fallback off

} // shader

代码

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

/// 

/// 把画面左右镜像
/// 
public class FrontCameraInvertImage : MonoBehaviour
{
	private bool isReverting = true;
	// Start is called before the first frame update
	void Start()
    {
    }
    // Update is called once per frame
    void Update()
    {
		if (Input.GetKeyDown(KeyCode.Space))
		{
			isReverting = !isReverting;
		}
	}

	public bool NeedRevert = false;
	public Shader invertShader;

	static Material m_Material = null;
	protected Material material
	{
		get
		{
			if (m_Material == null)
			{
				m_Material = new Material(invertShader);
				m_Material.hideFlags = HideFlags.DontSave;
			}
			return m_Material;
		}
	}

	protected void OnDisable()
	{
		if (m_Material)
		{
			DestroyImmediate(m_Material);
		}
	}

	// Called by the camera to apply the image effect
	void OnRenderImage(RenderTexture source, RenderTexture destination)
	{
		if (NeedRevert && isReverting)
		{
			if (Screen.orientation == ScreenOrientation.Portrait || Screen.orientation == ScreenOrientation.PortraitUpsideDown)
			{
				material.SetFloat("_AxisX", 0);
			}
			else
			{
				material.SetFloat("_AxisX", 1);
			}

			Graphics.Blit(source, destination, material);
		}
		else Graphics.Blit(source, destination);
	}
}

把代码挂在到如图所示的相机中，把shader拉到右侧的invert Shader中，勾上NeedRevert即可，我代码中设置了敲击空格开启或关闭镜像。

shader文件创建：

引用：主要代码来源