建立屏幕后处理脚本
首先创建脚本检查当前脚本是否支持，绑定在摄像机上；后面的屏幕特效继承该类即可；
using UnityEngine;
using System.Collections;
[ExecuteInEditMode]
[RequireComponent (typeof(Camera))]
public class PostEffectsBase : MonoBehaviour {
// Called when start
//检查各种资源和条件是否满足
protected void CheckResources() {
bool isSupported = CheckSupport();
if (isSupported == false) {
NotSupported();
}
}
// Called in CheckResources to check support on this platform
protected bool CheckSupport() {
if (SystemInfo.supportsImageEffects == false || SystemInfo.supportsRenderTextures == false) {
Debug.LogWarning("This platform does not support image effects or render textures.");
return false;
}
return true;
}
// Called when the platform doesn't support this effect
protected void NotSupported() {
enabled = false;
}
protected void Start() {
CheckResources();
}
// Called when need to create the material used by this effect
protected Material CheckShaderAndCreateMaterial(Shader shader, Material material) {
if (shader == null) {
return null;
}
if (shader.isSupported && material && material.shader == shader)
return material;
if (!shader.isSupported) {
return null;
}
else {
material = new Material(shader);
material.hideFlags = HideFlags.DontSave;
if (material)
return material;
else
return null;
}
}
}
调整屏幕亮度、饱和度和对比度
该脚本给摄像机
using UnityEngine;
using System.Collections;
public class BrightnessSaturationAndContrast : PostEffectsBase {
public Shader briSatConShader;
private Material briSatConMaterial;
public Material material {
get {
briSatConMaterial = CheckShaderAndCreateMaterial(briSatConShader, briSatConMaterial);
return briSatConMaterial;
}
}
[Range(0.0f, 3.0f)]
public float brightness = 1.0f;
[Range(0.0f, 3.0f)]
public float saturation = 1.0f;
[Range(0.0f, 3.0f)]
public float contrast = 1.0f;
//OnRenderImage得到当前屏幕图像，利用Graphics.Blit处理后给RenderTexture
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);
}
}
}
把该shader拖到脚本属性中
// Upgrade NOTE: replaced 'mul(UNITY_MATRIX_MVP,*)' with 'UnityObjectToClipPos(*)'
Shader "Unity Shaders Book/Chapter 12/Brightness Saturation And Contrast" {
Properties {
_MainTex ("Base (RGB)", 2D) = "white" {
}
_Brightness ("Brightness", Float) = 1
_Saturation("Saturation", Float) = 1
_Contrast("Contrast", Float) = 1
}
SubShader {
Pass {
//防止对其他物体产生影响，屏幕后处理相当于绘制一个和屏幕相同大小的四边形面片
ZTest Always Cull Off ZWrite Off
CGPROGRAM
#pragma vertex vert
#pragma fragment frag
#include "UnityCG.cginc"
sampler2D _MainTex;
half _Brightness;
half _Saturation;
half _Contrast;
struct v2f {
float4 pos : SV_POSITION;
half2 uv: TEXCOORD0;
};
v2f vert(appdata_img v) {
v2f o;
o.pos = UnityObjectToClipPos(v.vertex);
o.uv = v.texcoord;
return o;
}
fixed4 frag(v2f i) : SV_Target {
fixed4 renderTex = tex2D(_MainTex, i.uv);
// Apply brightness
fixed3 finalColor = renderTex.rgb * _Brightness;
// Apply saturation
//计算该像素对应的亮度值，创建一个饱和度为0的颜色值
fixed luminance = 0.2125 * renderTex.r + 0.7154 * renderTex.g + 0.0721 * renderTex.b;
fixed3 luminanceColor = fixed3(luminance, luminance, luminance);
//_Saturation插值，得到饱和度
finalColor = lerp(luminanceColor, finalColor, _Saturation);
// Apply contrast
//创建对比度为0的颜色值
fixed3 avgColor = fixed3(0.5, 0.5, 0.5);
finalColor = lerp(avgColor, finalColor, _Contrast);
return fixed4(finalColor, renderTex.a);
}
ENDCG
}
}
Fallback Off
}
边缘检测实现描边
边缘检测要用卷积核来做，计算梯度值
脚本
using UnityEngine;
using System.Collections;
public class EdgeDetection : PostEffectsBase {
public Shader edgeDetectShader;
private Material edgeDetectMaterial = null;
public Material material {
get {
edgeDetectMaterial = CheckShaderAndCreateMaterial(edgeDetectShader, edgeDetectMaterial);
return edgeDetectMaterial;
}
}
[Range(0.0f, 1.0f)]
//边缘线强度，0时直接叠加在原图，1时只会看见边缘
public float edgesOnly = 0.0f;
//描边颜色
public Color edgeColor = Color.black;
public Color backgroundColor = Color.white;
void OnRenderImage (RenderTexture src, RenderTexture dest) {
if (material != null) {
material.SetFloat("_EdgeOnly", edgesOnly);
material.SetColor("_EdgeColor", edgeColor);
material.SetColor("_BackgroundColor", backgroundColor);
Graphics.Blit(src, dest, material);
} else {
Graphics.Blit(src, dest);
}
}
}
shader（使用sobel）
// Upgrade NOTE: replaced 'mul(UNITY_MATRIX_MVP,*)' with 'UnityObjectToClipPos(*)'
Shader "Unity Shaders Book/Chapter 12/Edge Detection" {
Properties {
_MainTex ("Base (RGB)", 2D) = "white" {
}
_EdgeOnly ("Edge Only", Float) = 1.0
_EdgeColor ("Edge Color", Color) = (0, 0, 0, 1)
_BackgroundColor ("Background Color", Color) = (1, 1, 1, 1)
}
SubShader {
Pass {
ZTest Always Cull Off ZWrite Off
CGPROGRAM
#include "UnityCG.cginc"
#pragma vertex vert
#pragma fragment fragSobel
sampler2D _MainTex;
//每个纹素的大小，如512*512，纹素就是1/512
//因为卷积需要对相邻区域纹理采样，利用它计算各个相邻区域的纹理坐标
uniform half4 _MainTex_TexelSize;
fixed _EdgeOnly;
fixed4 _EdgeColor;
fixed4 _BackgroundColor;
struct v2f {
float4 pos : SV_POSITION;
half2 uv[9] : TEXCOORD0;
};
v2f vert(appdata_img v) {
v2f o;
o.pos = UnityObjectToClipPos(v.vertex);
half2 uv = v.texcoord;
//9个区域
o.uv[0] = uv + _MainTex_TexelSize.xy * half2(-1, -1);
o.uv[1] = uv + _MainTex_TexelSize.xy * half2(0, -1);
o.uv[2] = uv + _MainTex_TexelSize.xy * half2(1, -1);
o.uv[3] = uv + _MainTex_TexelSize.xy * half2(-1, 0);
o.uv[4] = uv + _MainTex_TexelSize.xy * half2(0, 0);
o.uv[5] = uv + _MainTex_TexelSize.xy * half2(1, 0);
o.uv[6] = uv + _MainTex_TexelSize.xy * half2(-1, 1);
o.uv[7] = uv + _MainTex_TexelSize.xy * half2(0, 1);
o.uv[8] = uv + _MainTex_TexelSize.xy * half2(1, 1);
return o;
}
fixed luminance(fixed4 color) {
return 0.2125 * color.r + 0.7154 * color.g + 0.0721 * color.b;
}
half Sobel(v2f i) {
const half Gx[9] = {
-1, 0, 1,
-2, 0, 2,
-1, 0, 1};
const half Gy[9] = {
-1, -2, -1,
0, 0, 0,
1, 2, 1};
half texColor;
half edgeX = 0;
half edgeY = 0;
for (int it = 0; it < 9; it++) {
texColor = luminance(tex2D(_MainTex, i.uv[it]));
edgeX += texColor * Gx[it];
edgeY += texColor * Gy[it];
}
//值越小越可能是边缘点
half edge = 1 - abs(edgeX) - abs(edgeY);
return edge;
}
fixed4 fragSobel(v2f i) : SV_Target {
//就散当前像素的梯度值
half edge = Sobel(i);
//计算背景为原图下的颜色值
fixed4 withEdgeColor = lerp(_EdgeColor, tex2D(_MainTex, i.uv[4]), edge);
//计算背景为纯色下的颜色值
fixed4 onlyEdgeColor = lerp(_EdgeColor, _BackgroundColor, edge);
//插值得到最终的像素值
return lerp(withEdgeColor, onlyEdgeColor, _EdgeOnly);
}
ENDCG
}
}
FallBack Off
}
高斯模糊
高斯模糊维数越高，影响越大，领域像素距离当前像素越近，影响越大；
脚本
using UnityEngine;
using System.Collections;
public class GaussianBlur : PostEffectsBase {
public Shader gaussianBlurShader;
private Material gaussianBlurMaterial = null;
public Material material {
get {
gaussianBlurMaterial = CheckShaderAndCreateMaterial(gaussianBlurShader, gaussianBlurMaterial);
return gaussianBlurMaterial;
}
}
// Blur iterations - larger number means more blur.
[Range(0, 4)]
//高斯模糊迭代次数
public int iterations = 3;
// Blur spread for each iteration - larger value means more blur
[Range(0.2f, 3.0f)]
//模糊范围，值越大，模糊程度越高，但不会影响采样次数
public float blurSpread = 0.6f;
[Range(1, 8)]
//缩放系数，值越大，需要处理的像素越少，进一步提高模糊程度
public int downSample = 2;
/// 1st edition: just apply blur
// void OnRenderImage(RenderTexture src, RenderTexture dest) {
// if (material != null) {
// int rtW = src.width;
// int rtH = src.height;
// RenderTexture buffer = RenderTexture.GetTemporary(rtW, rtH, 0);
//
// // Render the vertical pass
// Graphics.Blit(src, buffer, material, 0);
// // Render the horizontal pass
// Graphics.Blit(buffer, dest, material, 1);
//
// RenderTexture.ReleaseTemporary(buffer);
// } else {
// Graphics.Blit(src, dest);
// }
// }
/// 2nd edition: scale the render texture
// void OnRenderImage (RenderTexture src, RenderTexture dest) {
// if (material != null) {
// int rtW = src.width/downSample;
// int rtH = src.height/downSample;
// RenderTexture buffer = RenderTexture.GetTemporary(rtW, rtH, 0);
// buffer.filterMode = FilterMode.Bilinear;
//
// // Render the vertical pass
// Graphics.Blit(src, buffer, material, 0);
// // Render the horizontal pass
// Graphics.Blit(buffer, dest, material, 1);
//
// RenderTexture.ReleaseTemporary(buffer);
// } else {
// Graphics.Blit(src, dest);
// }
// }
/// 3rd edition: use iterations for larger blur
void OnRenderImage (RenderTexture src, RenderTexture dest) {
if (material != null) {
int rtW = src.width/downSample;
int rtH = src.height/downSample;
RenderTexture buffer0 = RenderTexture.GetTemporary(rtW, rtH, 0);
buffer0.filterMode = FilterMode.Bilinear;
Graphics.Blit(src, buffer0);
for (int i = 0; i < iterations; i++) {
material.SetFloat("_BlurSize", 1.0f + i * blurSpread);
RenderTexture buffer1 = RenderTexture.GetTemporary(rtW, rtH, 0);
// Render the vertical pass
Graphics.Blit(buffer0, buffer1, material, 0);
RenderTexture.ReleaseTemporary(buffer0);
buffer0 = buffer1;
buffer1 = RenderTexture.GetTemporary(rtW, rtH, 0);
// Render the horizontal pass
Graphics.Blit(buffer0, buffer1, material, 1);
RenderTexture.ReleaseTemporary(buffer0);
buffer0 = buffer1;
}
Graphics.Blit(buffer0, dest);
RenderTexture.ReleaseTemporary(buffer0);
} else {
Graphics.Blit(src, dest);
}
}
}
shader
// Upgrade NOTE: replaced 'mul(UNITY_MATRIX_MVP,*)' with 'UnityObjectToClipPos(*)'
Shader "Unity Shaders Book/Chapter 12/Gaussian Blur" {
Properties {
_MainTex ("Base (RGB)", 2D) = "white" {
}
_BlurSize ("Blur Size", Float) = 1.0
}
SubShader {
//避免每次都写一样的frag函数，pass中可以直接调用
CGINCLUDE
#include "UnityCG.cginc"
sampler2D _MainTex;
half4 _MainTex_TexelSize;
float _BlurSize;
struct v2f {
float4 pos : SV_POSITION;
half2 uv[5]: TEXCOORD0;
};
//
v2f vertBlurVertical(appdata_img v) {
v2f o;
o.pos = UnityObjectToClipPos(v.vertex);
half2 uv = v.texcoord;
o.uv[0] = uv;
o.uv[1] = uv + float2(0.0, _MainTex_TexelSize.y * 1.0) * _BlurSize;
o.uv[2] = uv - float2(0.0, _MainTex_TexelSize.y * 1.0) * _BlurSize;
o.uv[3] = uv + float2(0.0, _MainTex_TexelSize.y * 2.0) * _BlurSize;
o.uv[4] = uv - float2(0.0, _MainTex_TexelSize.y * 2.0) * _BlurSize;
return o;
}
v2f vertBlurHorizontal(appdata_img v) {
v2f o;
o.pos = UnityObjectToClipPos(v.vertex);
half2 uv = v.texcoord;
//5*5高斯核可以拆成两个大小为5的一维高斯核，因此只需要5个纹理坐标
//当前采样纹理
o.uv[0] = uv;
//对领域采样，_BlurSize控制采样距离，值越大，越模糊
o.uv[1] = uv + float2(_MainTex_TexelSize.x * 1.0, 0.0) * _BlurSize;
o.uv[2] = uv - float2(_MainTex_TexelSize.x * 1.0, 0.0) * _BlurSize;
o.uv[3] = uv + float2(_MainTex_TexelSize.x * 2.0, 0.0) * _BlurSize;
o.uv[4] = uv - float2(_MainTex_TexelSize.x * 2.0, 0.0) * _BlurSize;
return o;
}
fixed4 fragBlur(v2f i) : SV_Target {
//因为高斯核对称性，本来5个，只需要3个
float weight[3] = {
0.4026, 0.2442, 0.0545};
fixed3 sum = tex2D(_MainTex, i.uv[0]).rgb * weight[0];
for (int it = 1; it < 3; it++) {
sum += tex2D(_MainTex, i.uv[it*2-1]).rgb * weight[it];
sum += tex2D(_MainTex, i.uv[it*2]).rgb * weight[it];
}
return fixed4(sum, 1.0);
}
ENDCG
ZTest Always Cull Off ZWrite Off
Pass {
//方便其他的shader能直接调用
NAME "GAUSSIAN_BLUR_VERTICAL"
CGPROGRAM
#pragma vertex vertBlurVertical
#pragma fragment fragBlur
ENDCG
}
Pass {
NAME "GAUSSIAN_BLUR_HORIZONTAL"
CGPROGRAM
#pragma vertex vertBlurHorizontal
#pragma fragment fragBlur
ENDCG
}
}
FallBack "Diffuse"
}
Bloom效果
将图像中较亮的区域扩散到周围的区域中。
步骤：1.根据一个阈值提取出图像中较亮区域，把它们存储在一张渲染纹理中；2.利用高斯模糊对其模糊，模拟光线扩散的效果；3.将其和原图像混合；
脚本
using UnityEngine;
using System.Collections;
public class Bloom : PostEffectsBase {
public Shader bloomShader;
private Material bloomMaterial = null;
public Material material {
get {
bloomMaterial = CheckShaderAndCreateMaterial(bloomShader, bloomMaterial);
return bloomMaterial;
}
}
// Blur iterations - larger number means more blur.
[Range(0, 4)]
public int iterations = 3;
// Blur spread for each iteration - larger value means more blur
[Range(0.2f, 3.0f)]
public float blurSpread = 0.6f;
[Range(1, 8)]
public int downSample = 2;
[Range(0.0f, 4.0f)]
//提取较亮区域的阈值大小，一般不会超过1，如果开启HDR，可能超过1
public float luminanceThreshold = 0.6f;
void OnRenderImage (RenderTexture src, RenderTexture dest) {
if (material != null) {
material.SetFloat("_LuminanceThreshold", luminanceThreshold);
int rtW = src.width/downSample;
int rtH = src.height/downSample;
RenderTexture buffer0 = RenderTexture.GetTemporary(rtW, rtH, 0);
buffer0.filterMode = FilterMode.Bilinear;
//第一个pass提取较亮区域，2、3模糊，第4个混合
Graphics.Blit(src, buffer0, material, 0);
for (int i = 0; i < iterations; i++) {
material.SetFloat("_BlurSize", 1.0f + i * blurSpread);
RenderTexture buffer1 = RenderTexture.GetTemporary(rtW, rtH, 0);
// Render the vertical pass
Graphics.Blit(buffer0, buffer1, material, 1);
RenderTexture.ReleaseTemporary(buffer0);
buffer0 = buffer1;
buffer1 = RenderTexture.GetTemporary(rtW, rtH, 0);
// Render the horizontal pass
Graphics.Blit(buffer0, buffer1, material, 2);
RenderTexture.ReleaseTemporary(buffer0);
buffer0 = buffer1;
}
material.SetTexture ("_Bloom", buffer0);
Graphics.Blit (src, dest, material, 3);
RenderTexture.ReleaseTemporary(buffer0);
} else {
Graphics.Blit(src, dest);
}
}
}
shader
// Upgrade NOTE: replaced 'mul(UNITY_MATRIX_MVP,*)' with 'UnityObjectToClipPos(*)'
Shader "Unity Shaders Book/Chapter 12/Bloom" {
Properties {
_MainTex ("Base (RGB)", 2D) = "white" {
}
//高斯模糊后的较亮区域
_Bloom ("Bloom (RGB)", 2D) = "black" {
}
//阈值
_LuminanceThreshold ("Luminance Threshold", Float) = 0.5
//模糊范围
_BlurSize ("Blur Size", Float) = 1.0
}
SubShader {
CGINCLUDE
#include "UnityCG.cginc"
sampler2D _MainTex;
half4 _MainTex_TexelSize;
sampler2D _Bloom;
float _LuminanceThreshold;
float _BlurSize;
struct v2f {
float4 pos : SV_POSITION;
half2 uv : TEXCOORD0;
};
v2f vertExtractBright(appdata_img v) {
v2f o;
o.pos = UnityObjectToClipPos(v.vertex);
o.uv = v.texcoord;
return o;
}
fixed luminance(fixed4 color) {
return 0.2125 * color.r + 0.7154 * color.g + 0.0721 * color.b;
}
fixed4 fragExtractBright(v2f i) : SV_Target {
fixed4 c = tex2D(_MainTex, i.uv);
//亮度值-阈值，并将结果截取到0-1
fixed val = clamp(luminance(c) - _LuminanceThreshold, 0.0, 1.0);
//提取后的亮部区域
return c * val;
}
struct v2fBloom {
float4 pos : SV_POSITION;
half4 uv : TEXCOORD0;
};
//混合用的顶点和片元
v2fBloom vertBloom(appdata_img v) {
v2fBloom o;
o.pos = UnityObjectToClipPos (v.vertex);
//xy对应原图像的纹理坐标
o.uv.xy = v.texcoord;
//zw对应模糊后较亮区域的纹理坐标
o.uv.zw = v.texcoord;
//根据平台差异化处理
#if UNITY_UV_STARTS_AT_TOP
if (_MainTex_TexelSize.y < 0.0)
o.uv.w = 1.0 - o.uv.w;
#endif
return o;
}
fixed4 fragBloom(v2fBloom i) : SV_Target {
return tex2D(_MainTex, i.uv.xy) + tex2D(_Bloom, i.uv.zw);
}
ENDCG
ZTest Always Cull Off ZWrite Off
Pass {
CGPROGRAM
#pragma vertex vertExtractBright
#pragma fragment fragExtractBright
ENDCG
}
//必须大写
UsePass "Unity Shaders Book/Chapter 12/Gaussian Blur/GAUSSIAN_BLUR_VERTICAL"
UsePass "Unity Shaders Book/Chapter 12/Gaussian Blur/GAUSSIAN_BLUR_HORIZONTAL"
Pass {
CGPROGRAM
#pragma vertex vertBloom
#pragma fragment fragBloom
ENDCG
}
}
FallBack Off
}
运动模糊
方法一：利用一块累积缓存来混合多张连续的图像，取它们的平均值作为最后的图像，但性能消耗很大，因为这样需要同一帧渲染多次场景。
方法二：创建和使用速度缓存，它存储了各个像素当前的运动速度，然后利用该值来决定模糊的方向和大小；
这里使用方法一的改进，不需要一帧渲染多次，但需要保存之前的渲染结果；
using UnityEngine;
using System.Collections;
public class MotionBlur : PostEffectsBase {
public Shader motionBlurShader;
private Material motionBlurMaterial = null;
public Material material {
get {
motionBlurMaterial = CheckShaderAndCreateMaterial(motionBlurShader, motionBlurMaterial);
return motionBlurMaterial;
}
}
[Range(0.0f, 0.9f)]
//值越大，运动拖尾的效果越明显
public float blurAmount = 0.5f;
//用来保存之前图像叠加的效果
private RenderTexture accumulationTexture;
//脚本不运行时，立即销毁，因为希望下一次开始应用运动模糊时重新叠加图像
void OnDisable() {
DestroyImmediate(accumulationTexture);
}
void OnRenderImage (RenderTexture src, RenderTexture dest) {
if (material != null) {
// Create the accumulation texture
if (accumulationTexture == null || accumulationTexture.width != src.width || accumulationTexture.height != src.height) {
DestroyImmediate(accumulationTexture);
accumulationTexture = new RenderTexture(src.width, src.height, 0);
//不会显示在Hierarcy中也不会保存在场景中，因为OnDisable可以控制销毁
accumulationTexture.hideFlags = HideFlags.HideAndDontSave;
//初始化
Graphics.Blit(src, accumulationTexture);
}
// We are accumulating motion over frames without clear/discard
// by design, so silence any performance warnings from Unity
//渲染纹理的恢复操作，发生在渲染到纹理而该纹理又没有被提前清空或销毁的情况下，用在这里因为每次调用OnRenderImage都是混合；
accumulationTexture.MarkRestoreExpected();
material.SetFloat("_BlurAmount", 1.0f - blurAmount);
Graphics.Blit (src, accumulationTexture, material);
Graphics.Blit (accumulationTexture, dest);
} else {
Graphics.Blit(src, dest);
}
}
}
shader
// Upgrade NOTE: replaced 'mul(UNITY_MATRIX_MVP,*)' with 'UnityObjectToClipPos(*)'
Shader "Unity Shaders Book/Chapter 12/Motion Blur" {
Properties {
_MainTex ("Base (RGB)", 2D) = "white" {
}
_BlurAmount ("Blur Amount", Float) = 1.0
}
SubShader {
CGINCLUDE
#include "UnityCG.cginc"
sampler2D _MainTex;
fixed _BlurAmount;
struct v2f {
float4 pos : SV_POSITION;
half2 uv : TEXCOORD0;
};
v2f vert(appdata_img v) {
v2f o;
o.pos = UnityObjectToClipPos(v.vertex);
o.uv = v.texcoord;
return o;
}
//更新渲染纹理的rgb通道
fixed4 fragRGB (v2f i) : SV_Target {
return fixed4(tex2D(_MainTex, i.uv).rgb, _BlurAmount);
}
//A通道，直接返回采样结果，不让其受到混合时使用的透明度值的影响
half4 fragA (v2f i) : SV_Target {
return tex2D(_MainTex, i.uv);
}
ENDCG
ZTest Always Cull Off ZWrite Off
//定义两个pass是因为更新rgb时需要设置A通道来混合图像，但又不希望a通道的值写入渲染纹理
Pass {
Blend SrcAlpha OneMinusSrcAlpha
ColorMask RGB
CGPROGRAM
#pragma vertex vert
#pragma fragment fragRGB
ENDCG
}
Pass {
Blend One Zero
ColorMask A
CGPROGRAM
#pragma vertex vert
#pragma fragment fragA
ENDCG
}
}
FallBack Off
}