亮度，饱和度，对比度后处理效果

这里需要使用 Unity 的 OnRenderImage 函数对渲染后的画面进行处理
其中还需要使用 Graphics.Blit(src, dest) 函数来对渲染纹理进行对应的shader处理

• 脚本

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

[ExecuteAlways]
[RequireComponent(typeof(Camera))]
public class PostEffectBase : MonoBehaviour
{
    
    
    protected Material CheckShaderAndCreateMaterial(Shader shader, Material material)
    {
    
    
        if (shader == null) return null;

        if (shader.isSupported && material != null && material.shader == shader)
            return material;

        if (!shader.isSupported) return null;

        material = new Material(shader) {
    
     hideFlags = HideFlags.DontSave };
        return material;
    }
}

using System;
using UnityEngine;

public class BrightnessSaturationAndContrast : PostEffectBase
{
    
    
    public Shader briSatConShader;
    private Material briSatConMaterial;

    public Material material
    {
    
    
        get
        {
    
    
            briSatConMaterial = CheckShaderAndCreateMaterial(briSatConShader, briSatConMaterial);
            return briSatConMaterial;
        }
    }

    [Range(0f, 3f)]
    public float brightness = 1.0f;
    [Range(0f, 3f)]
    public float saturation = 1.0f;
    [Range(0f, 3f)]
    public float contrast = 1.0f;

    private void OnRenderImage(RenderTexture src, RenderTexture dest)
    {
    
    
        if (material != null)
        {
    
    
            material.SetFloat("_Brightness", brightness);
            material.SetFloat("_Saturation", saturation);
            material.SetFloat("_Contrast", contrast);
            
            Graphics.Blit(src, dest, material);
        }
        else Graphics.Blit(src, dest);
    }
}

• shader

Shader "Hidden/Brightness_Saturation_And_Contrast"
{
    
    
    Properties
    {
    
    
        _MainTex ("Texture", 2D) = "white" {
    
    }
        _Brightness ("Brightess", Float) = 1.0
        _Saturation ("Saturation", Float) = 1.0
        _Contrast ("Contrast", Float) = 1.0
    }
    SubShader
    {
    
    
        Cull Off ZWrite Off ZTest Always

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

            struct a2f
            {
    
    
                float4 vertex : POSITION;
                float2 uv : TEXCOORD0;
            };

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

            sampler2D _MainTex;
            half _Brightness;
            half _Saturation;
            half _Contrast;

            v2f vert (a2f v)
            {
    
    
                v2f o;
                o.vertex = UnityObjectToClipPos(v.vertex);
                o.uv = v.uv;
                return o;
            }

            fixed4 frag (v2f i) : SV_Target
            {
    
    
                fixed4 renderTex = tex2D(_MainTex, i.uv);

                fixed3 finalColor = renderTex.rgb * _Brightness;

                fixed luminance = dot(unity_ColorSpaceLuminance, renderTex);
                fixed3 luminanceColor = fixed3(luminance, luminance, luminance);
                finalColor = lerp(luminance, finalColor, _Saturation);

                finalColor = lerp(unity_ColorSpaceGrey.xyz, finalColor, _Contrast);
                return fixed4(finalColor, renderTex.a);
            }
            ENDCG
        }
    }
}

参考 Unity Shader 入门精要这本书