Unity Shader——夜晚视觉屏幕特效（night vision Screen Effect）

本文参考《Unity Shaders and Effects CookBook》。

这一篇夜晚视觉的效果跟上篇的老电影特效效果很类似，首先看下什么是夜晚视觉的效果：



分析下操作思路：



需要的图片素材如下：



下面的脚本处理跟前面的几篇一样的模式，一个shader一个cs脚本：

Shader脚本：
Shader "MyShaders/NightVisionEffectShader"
{
Properties
{
_MainTex ("Base (RGB)", 2D) = "white" {}
_VignetteTex ("Vignette Texture", 2D) = "white"{}
_ScanLineTex ("Scan Line Texture", 2D) = "white"{}
_NoiseTex ("Noise Texture", 2D) = "white"{}
_NoiseXSpeed ("Noise X Speed", Float) = 100.0
_NoiseYSpeed ("Noise Y Speed", Float) = 100.0
_ScanLineTileAmount ("Scan Line Tile Amount", Float) = 4.0
_NightVisionColor ("Night Vision Color", Color) = (1,1,1,1)
_Contrast ("Contrast", Range(0,4)) = 2
_Brightness ("Brightness", Range(0,2)) = 1
_RandomValue ("Random Value", Float) = 0
_distortion ("Distortion", Float) = 0.2
_scale ("Scale (Zoom)", Float) = 0.8
}

SubShader
{
Pass
{
CGPROGRAM
#pragma vertex vert_img
#pragma fragment frag
#pragma fragmentoption ARB_precision_hint_fastest
#include "UnityCG.cginc"

uniform sampler2D _MainTex;
uniform sampler2D _VignetteTex;
uniform sampler2D _ScanLineTex;
uniform sampler2D _NoiseTex;
fixed4 _NightVisionColor;
fixed _Contrast;
fixed _ScanLineTileAmount;
fixed _Brightness;
fixed _RandomValue;
fixed _NoiseXSpeed;
fixed _NoiseYSpeed;
fixed _distortion;
fixed _scale;

float2 barrelDistortion(float2 coord)
{

float2 h = coord.xy - float2(0.5, 0.5);
float r2 = h.x * h.x + h.y * h.y;
float f = 1.0 + r2 * (_distortion * sqrt(r2));

return f * _scale * h + 0.5;
}

fixed4 frag(v2f_img i) : COLOR
{
//Get the colors from the RenderTexture and the uv's
//from the v2f_img struct
half2 distortedUV = barrelDistortion(i.uv);
fixed4 renderTex = tex2D(_MainTex, distortedUV);
fixed4 vignetteTex = tex2D(_VignetteTex, i.uv);

//Process scan lines and noise
half2 scanLinesUV = half2(i.uv.x * _ScanLineTileAmount, i.uv.y * _ScanLineTileAmount);
fixed4 scanLineTex = tex2D(_ScanLineTex, scanLinesUV);

half2 noiseUV = half2(i.uv.x + (_RandomValue * _SinTime.z * _NoiseXSpeed),
i.uv.y + (_Time.x * _NoiseYSpeed));
fixed4 noiseTex = tex2D(_NoiseTex, noiseUV);

// get the luminosity values from the render texture using the YIQ values.
fixed lum = dot (fixed3(0.299, 0.587, 0.114), renderTex.rgb);
lum += _Brightness;
fixed4 finalColor = (lum *2) + _NightVisionColor;

//Final output
finalColor = pow(finalColor, _Contrast);
finalColor *= vignetteTex;
finalColor *= scanLineTex * noiseTex;

return finalColor;
}

ENDCG
}
}
FallBack off
}


Cs脚本：
using UnityEngine;
using System.Collections;

[ExecuteInEditMode]
public class NightVisionEffect : MonoBehaviour
{
#region Variables
public Shader nightVisionShader;

public float contrast = 2.0f;
public float brightness = 1.0f;
public Color nightVisionColor = Color.white;

public Texture2D vignetteTexture;

public Texture2D scanLineTexture;
public float scanLineTileAmount = 4.0f;

public Texture2D nightVisionNoise;
public float noiseXSpeed = 100.0f;
public float noiseYSpeed = 100.0f;

public float distortion = 0.2f;
public float scale = 0.8f;

private float randomValue = 0.0f;
private Material curMaterial;
#endregion

#region Properties
Material material
{
get
{
if(curMaterial == null)
{
curMaterial = new Material(nightVisionShader);
curMaterial.hideFlags = HideFlags.HideAndDontSave;
}
return curMaterial;
}
}
#endregion

void Start()
{
if(!SystemInfo.supportsImageEffects)
{
enabled = false;
return;
}

if(!nightVisionShader && !nightVisionShader.isSupported)
{
enabled = false;
}
}

void OnRenderImage(RenderTexture sourceTexture, RenderTexture destTexture)
{
if(nightVisionShader != null)
{
material.SetFloat("_Contrast", contrast);
material.SetFloat("_Brightness", brightness);
material.SetColor("_NightVisionColor", nightVisionColor);
material.SetFloat("_RandomValue", randomValue);
material.SetFloat("_distortion", distortion);
material.SetFloat("_scale",scale);

if(vignetteTexture)
{
material.SetTexture("_VignetteTex", vignetteTexture);
}

if(scanLineTexture)
{
material.SetTexture("_ScanLineTex", scanLineTexture);
material.SetFloat("_ScanLineTileAmount", scanLineTileAmount);
}

if(nightVisionNoise)
{
material.SetTexture("_NoiseTex", nightVisionNoise);
material.SetFloat("_NoiseXSpeed", noiseXSpeed);
material.SetFloat("_NoiseYSpeed", noiseYSpeed);
}

Graphics.Blit(sourceTexture, destTexture, material);
}
else
{
Graphics.Blit(sourceTexture, destTexture);
}
}

void Update()
{
contrast = Mathf.Clamp(contrast, 0f,4f);
brightness = Mathf.Clamp(brightness, 0f, 2f);
randomValue = Random.Range(-1f,1f);
distortion = Mathf.Clamp(distortion, -1f,1f);
scale = Mathf.Clamp(scale, 0f, 3f);
}

void OnDisable()
{
if(curMaterial)
{
DestroyImmediate(curMaterial);
}
}
}


最终调控的面板参数如图：



最终的效果如图：



贴图素材下载