[游戏开发]Unity 任意门 or 穿梭于过去或未来

using System.Collections;
using System.Collections.Generic;
using UnityEngine;
using UnityEngine.Rendering;
using UnityEngine.SceneManagement;

public class PastOrFuture : MonoBehaviour
{
	public Camera _activeCamera;
	public Camera _hiddenCamera;
	public MeshRenderer Mirror;
	public int playerLayer;
	public int activeLayer;
	public int hiddenLayer;

	private void Awake()
	{
		var rt = new RenderTexture(Screen.width, Screen.height, 24);
		Mirror.material.SetTexture("_TimeCrackTexture", rt);
		_hiddenCamera.targetTexture = rt;
		Physics.IgnoreLayerCollision(playerLayer, activeLayer, false);
		Physics.IgnoreLayerCollision(playerLayer, hiddenLayer, true);

		SceneManager.LoadScene("Past", LoadSceneMode.Additive);
	}

    public void SwapScene()
	{
		_activeCamera.targetTexture = _hiddenCamera.targetTexture;
		_hiddenCamera.targetTexture = null;

		var swapCamera = _activeCamera;
		_activeCamera = _hiddenCamera;
		_hiddenCamera = swapCamera;

		int layer = activeLayer;
		activeLayer = hiddenLayer;
		hiddenLayer = layer;

		Physics.IgnoreLayerCollision(playerLayer, activeLayer, false);
		Physics.IgnoreLayerCollision(playerLayer, hiddenLayer, true);
	}
}

Shader "LSQ/EffectAchievement/PastOrFuture"
{
    Properties
    {
        
    }
    SubShader
    {
		Tags { "RenderType"="Opaque" }
		LOD 100

		Pass
		{
			CGPROGRAM
			#pragma vertex vert
			#pragma fragment frag
			
			#include "UnityCG.cginc"
			#include "UnityStandardUtils.cginc"

			struct VertIn
			{
				float4 vertex : POSITION;
			};

			struct FragIn
			{
				float4 vertex : SV_POSITION;
				float4 screen_GrabUV : TEXCOORD1;
				float3 screen_uv : TEXCOORD2;
			};
			
			FragIn vert (VertIn v)
			{
				FragIn o;
				o.vertex = UnityObjectToClipPos(v.vertex);
				o.screen_GrabUV = ComputeGrabScreenPos(o.vertex);
				//o.screen_uv = float3((o.vertex.xy + o.vertex.w) * 0.5, o.vertex.w);

				return o;
			}

			sampler2D _TimeCrackTexture;

			fixed4 frag (FragIn i) : SV_Target
			{
				fixed4 col = tex2Dproj(_TimeCrackTexture, UNITY_PROJ_COORD(i.screen_GrabUV));

				//fixed4 col = tex2D(_TimeCrackTexture, i.screen_uv.xy / i.screen_uv.z);

				return col;
			}
			ENDCG
		}
    }
}