Unity shader学习之屏幕后期效果之调整屏幕亮度，饱和度，对比度

Unity的屏幕后期处理效果，使用MonoBehaviour.OnRenderImage来实现。

转载请注明出处：http://www.cnblogs.com/jietian331/p/7228063.html

如代码如下：

基类：

 using UnityEngine;

 [RequireComponent(typeof(Camera))]
 public abstract class PostEffectRenderer : GameBehaviour
 {
     protected abstract string ShaderName { get; }

     Material m_mat;

     void Start()
     {
         if (!SystemInfo.supportsImageEffects)
             NotSupport();
     }

     protected virtual void OnRenderImage(RenderTexture src, RenderTexture dest)
     {
         Graphics.Blit(src, dest, Mat);
     }

     protected void NotSupport()
     {
         enabled = false;
     }

     protected Material Mat
     {
         get
         {
             if (!m_mat)
             {
                 Shader shader = Shader.Find(ShaderName);
                 if (shader != null && shader.isSupported)
                     m_mat = new Material(shader);
                 else
                     NotSupport();
             }
             return m_mat;
         }
     }
 }

PostEffectRenderer

子类实现 ：

 using UnityEngine;

 public class ScreencolorsAdjuster : PostEffectRenderer
 {
     [SerializeField]
     float m_brightness = ;
     [SerializeField]
     float m_saturation = ;
     [SerializeField]
     float m_contrast = ;

     protected override void OnRenderImage(RenderTexture src, RenderTexture dest)
     {
         base.Mat.SetFloat("_Brightness", m_brightness);
         base.Mat.SetFloat("_Saturation", m_saturation);
         base.Mat.SetFloat("_Contrast", m_contrast);
         base.OnRenderImage(src, dest);
     }

     protected override string ShaderName
     {
         get { return "Custom/Screencolors Adjuster"; }
     }
 }

ScreencolorsAdjuster

shader如下：

 Shader "Custom/Screencolors Adjuster"
 {
     Properties
     {
         _MainTex("Main Texture", 2D) = "white" {}
         _Brightness("Brightness", Float) =
         _Saturation("Saturation", Float) =
         _Contrast("Contrast", Float) =
     }

     SubShader
     {
         Pass
         {
             ZTest Always
             ZWrite Off
             Cull Off

             CGPROGRAM
             #pragma vertex vert
             #pragma fragment frag

             sampler2D _MainTex;
             float _Brightness;
             float _Saturation;
             float _Contrast;

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

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

             v2f vert(appdata v)
             {
                 v2f o;
                 o.pos = mul(UNITY_MATRIX_MVP, v.vertex);
                 o.uv = v.uv;

                 return o;
             }

             fixed4 frag(v2f i) : SV_TARGET
             {
                 fixed4 tex = tex2D(_MainTex, i.uv);

                 fixed3 finalCol = tex.rgb * _Brightness;

                 fixed luminance = dot(fixed3(0.2125, 0.7154, 0.0721), tex.rgb);
                 fixed3 luminanceCol = fixed3(luminance, luminance, luminance);
                 finalCol = lerp(finalCol, luminanceCol, _Saturation);

                 fixed3 avgCol = fixed3(0.5, 0.5, 0.5);
                 finalCol = lerp(finalCol, avgCol, _Contrast);

                 return fixed4(finalCol, tex.a);
             }

             ENDCG
         }
     }

     Fallback Off
 }

ScreencolorsAdjuster脚本挂在摄像机上：

调整参数，效果如下：