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;
        }
    }
}

子类实现 ：

using UnityEngine;

public class ScreencolorsAdjuster : PostEffectRenderer
{
    [SerializeField]
    float m_brightness = 1;
    [SerializeField]
    float m_saturation = 0;
    [SerializeField]
    float m_contrast = 0;

    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"; }
    }
}

shader如下：

Shader "Custom/Screencolors Adjuster"
{
    Properties
    {
        _MainTex("Main Texture", 2D) = "white" {}
        _Brightness("Brightness", Float) = 1
        _Saturation("Saturation", Float) = 0
        _Contrast("Contrast", Float) = 0
    }

    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：