Shader学习案例三---屏幕特效之色彩调节

更新：意外发现乐乐女神（《Unity Shader入门精要》的作者）早在csdn中写了很多案例，所以请观众转场吧，比我写的好太多，有清晰的解释，后续相同的不再写了，如果有我自己写的Shader，再贴出来供大家参考

来源

书名：Unity 5.x Shaders and Effects Cookbook

目标

调节屏幕的亮度、饱和度、对比度

过程

一、Unity操作

1. 新建场景，创建三个球体，分别赋予红、绿、蓝色的Material；

二、编写Shader

1. Properties块

Properties
{
_MainTex ("Texture", 2D) = "white" {}
_Brightness ("Brightness Amount",Range(0.0,1.0)) = 1.0
_Saturation ("Stauration Amount",Range(0.0,1.0)) = 1.0
_Contrast ("Contrast Amount",Range(0.0,1.0)) = 1.0
}

SubShader块

SubShader
{
Pass
{
CGPROGRAM
#pragma vertex vert_img
#pragma fragment frag
#pragma fragmentoption ARB_precision_hint_fastest

#include "UnityCG.cginc"

sampler2D _MainTex;
fixed _Brightness;
fixed _Saturation;
fixed _Contrast;

//自定义色彩调节函数
fixed3 BSCAdjust(fixed3 color,fixed brt,fixed sat,fixed cont){
//构造色彩中值
fixed3 avgLum = fixed3(0.5,0.5,0.5);
//构造调节系数
fixed3 lumcoeff = fixed3(0.2125,0.7154,0.0721);

//控制亮度Brightness
fixed3 brtColor = color * brt;
fixed intensityf = dot(brtColor,lumcoeff);
fixed3 intensity = fixed3(intensityf,intensityf,intensityf);

//控制饱和度
fixed3 satColor = lerp(intensity,brtColor,sat);

//控制对比度
fixed3 conColor = lerp(avgLum,satColor,cont);
return conColor;
}

fixed4 frag (v2f_img i) : SV_Target
{
fixed4 col = tex2D(_MainTex, i.uv);
// 调用调节函数
col.rgb = BSCAdjust(col.rgb,_Brightness,_Saturation,_Contrast);
return col;
}
ENDCG
}
}

至于实现原理，我也不知道。。。

三、编写C#脚本

脚本挂载到Camera上即可，代码：

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

[ExecuteInEditMode]
public class BSCAdjust : MonoBehaviour {

public Shader curShader;
[Header("Adjust Parameters")]
[Range(0.0f,1.0f)]
public float brightness = 1.0f;
[Range(0.0f,1.0f)]
public float saturation = 1.0f;
[Range(0.0f,1.0f)]
public float contrast = 1.0f;

private Material material;

public Material curMaterial {
get{
if (material == null) {
material = new Material (curShader);
material.hideFlags = HideFlags.HideAndDontSave;
}
return material;
}
}
// Use this for initialization
void Start () {
if (!SystemInfo.supportsImageEffects) {
enabled = false;
return;
}
}

void OnDisable(){
if (material != null) {
DestroyImmediate (material);
}
}

void OnRenderImage(RenderTexture srcTexture,RenderTexture destTexture){
if (curShader != null && curShader.isSupported) {
curMaterial.SetFloat ("_Brightness", brightness);
curMaterial.SetFloat ("_Saturation", saturation);
curMaterial.SetFloat ("_Contrast", contrast);
Graphics.Blit (srcTexture, destTexture, curMaterial);
} else {
Graphics.Blit (srcTexture, destTexture);
}
}
}

结果