Unity 屏幕特效后期处理 OnRenderImage

OnRenderImage 是专门给后期处理用的
把下面这个脚本挂在摄像机上

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

[ExecuteInEditMode, ImageEffectAllowedInSceneView]
public class ImageTest : MonoBehaviour
{
    
    
    [SerializeField] Material mat;
    [SerializeField] Shader bloomShader;

    const string m_bloomShaderID = "Hidden/NewImageEffectShader";

    private void Awake()
    {
    
    
        bloomShader = Shader.Find(m_bloomShaderID);
        mat = new Material(bloomShader);
    }

    private void OnRenderImage(RenderTexture source, RenderTexture destination)
    {
    
    
        Graphics.Blit(source, destination, mat);
    }
}

直接创建一个Image Effect Shader

Shader "Hidden/NewImageEffectShader"
{
    
    
    Properties
    {
    
    
        _MainTex ("Texture", 2D) = "white" {
    
    }
    }
    SubShader
    {
    
    
        // No culling or depth
        Cull Off ZWrite Off ZTest Always

        Pass
        {
    
    
            CGPROGRAM
            #pragma vertex vert
            #pragma fragment frag

            #include "UnityCG.cginc"

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

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

            v2f vert (appdata v)
            {
    
    
                v2f o;
                o.vertex = UnityObjectToClipPos(v.vertex);
                o.uv = v.uv;
                return o;
            }

            sampler2D _MainTex;

            fixed4 frag (v2f i) : SV_Target
            {
    
    
                fixed4 col = tex2D(_MainTex, i.uv);
                // just invert the colors
                col.rgb = 1 - col.rgb;
                return col;
            }
            ENDCG
        }
    }
}

他的作用非常简单
col.rgb = 1 - col.rgb;
就是让颜色反转

运行你会发现这个效果

左边是原始图像 右边是加工后的
原理是这个

可以看看这个
https://zhuanlan.zhihu.com/p/91390940