一个里表世界切换的shader效果

之前GGJ实现了一个，但是实现方式上有很多冗余。今天正好在做一个类似的东西，重新做了一个版本

还是当时美术画的素材:

由于里表世界是不同的内容，是两张材质。所以拆分成不同Layer之后，里世界单独渲染一次

最后用Graphics做一下混合的屏幕处理即可。

脚本:

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

public class CustomRender : MonoBehaviour
{
    public Material blendMat;
    public Transform maskMappingPoint;
    Camera mCacheCamera;


    void OnRenderImage(RenderTexture src, RenderTexture des)
    {
        if (mCacheCamera == null)
        {
            mCacheCamera = new GameObject("tempCamera").AddComponent<Camera>();
            mCacheCamera.transform.parent = transform;
        }

        mCacheCamera.gameObject.SetActive(true);
        mCacheCamera.CopyFrom(Camera.main);

        var tempRT = RenderTexture.GetTemporary(src.width, src.height);

        tempRT.DiscardContents();

        var normalWorldLayer = 1 << LayerMask.NameToLayer("NormalWorld");
        var madWorldLayer = 1 << LayerMask.NameToLayer("MadWorld");

        var cacheCullingMask = mCacheCamera.cullingMask;

        //------------------------------
        if ((mCacheCamera.cullingMask & normalWorldLayer) == normalWorldLayer)
        {
            mCacheCamera.cullingMask ^= normalWorldLayer;
        }

        mCacheCamera.cullingMask |= madWorldLayer;
        mCacheCamera.targetTexture = tempRT;
        mCacheCamera.Render();
        //------------Renderer mad world.

        //------------------------------

        Vector4 viewPortPoint = Camera.main.WorldToViewportPoint(maskMappingPoint.position);

        viewPortPoint -= new Vector4(0.5f, 0.5f);
        viewPortPoint.w = maskMappingPoint.localScale.x;

        blendMat.SetTexture("_MainTex", src);
        blendMat.SetTexture("_MadWorldTex", tempRT);
        blendMat.SetVector("_MaskOffset", viewPortPoint);
        Graphics.Blit(src, des, blendMat);
        //------------Blend.

        mCacheCamera.cullingMask = cacheCullingMask;
        RenderTexture.ReleaseTemporary(tempRT);
        mCacheCamera.gameObject.SetActive(false);
    }
}

Shader:

Shader "Unlit/BlendShader"
{
    Properties
    {
        _MainTex ("Texture", 2D) = "white" {}
        _MadWorldTex("MadWorld Texture", 2D) = "white" {}
        _MaskTex("Mask Texture", 2D) = "white" {}
        _MaskOffset("Mask Offset", vector) = (0,0,0,0)
    }

    SubShader
    {
        Tags { "RenderType"="Opaque" }
        LOD 100

        Pass
        {
            CGPROGRAM
            #pragma vertex vert
            #pragma fragment frag
            // make fog work
            #pragma multi_compile_fog
            
            #include "UnityCG.cginc"

            struct appdata
            {
                float4 vertex : POSITION;
                float2 uv : TEXCOORD0;
            };

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

            sampler2D _MainTex;
            float4 _MainTex_ST;
            float4 _MaskOffset;

            sampler2D _MadWorldTex;
            sampler2D _MaskTex;
            
            v2f vert (appdata v)
            {
                v2f o;
                o.vertex = UnityObjectToClipPos(v.vertex);
                o.uv = TRANSFORM_TEX(v.uv, _MainTex);
                return o;
            }
            
            fixed4 frag (v2f i) : SV_Target
            {
                fixed4 col1 = tex2D(_MainTex, i.uv);
                fixed4 col2 = tex2D(_MadWorldTex, i.uv);

#if UNITY_UV_STARTS_AT_TOP
                float grabSign = -_ProjectionParams.x;
#else
                float grabSign = _ProjectionParams.x;
#endif

                half2 uv = float2(1, grabSign) * (i.uv - half2(0.5, 0.5)) / _MaskOffset.ww + half2(0.5, 0.5);

                fixed4 mask = tex2D(_MaskTex, uv + _MaskOffset.xy);
                return lerp(col1, col2, 1-mask.a);
            }
            ENDCG
        }
    }
}