Unity对屏幕特定部分进行后期特效处理
发表于2018-09-10
最近在做一个效果：用一条线将整个屏幕分成两部分，一部分是灰色，一部分是彩色，线的位置是可变的
如果只是区分的话，简单的方法就是相机前加一个灰色quad，如下图，但明显不如灰化对比度高
下面就来实现下在unity中对屏幕特定部分进行后期特效处理。
首先，我们要建一个屏幕特效脚本挂在到相机上
using System;
using UnityEngine;
namespace UnityStandardAssets.ImageEffects
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[ExecuteInEditMode]
[RequireComponent (typeof(Camera))]
class SimplePostEffect : PostEffectsBase
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public Shader TintShader = null;
public Color TintColour;
private Material TintMaterial = null;
public override bool CheckResources ()
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CheckSupport (true);
TintMaterial = CheckShaderAndCreateMaterial (TintShader);
if (!isSupported)
ReportAutoDisable ();
return isSupported;
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void OnRenderImage (RenderTexture source, RenderTexture destination)
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if (CheckResources()==false)
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Graphics.Blit (source, destination);
return;
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TintMaterial.SetColor("TintColour", TintColour);
//Do a full screen pass using TintMaterial
Graphics.Blit (source, destination, TintMaterial);
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Graphics.Blit 位块传送，拷贝源纹理到目的渲染纹理。可简单理解为获取该相机的rendertexture作为纹理，通过指定shader再渲染一遍。
setvector函数用作将横线上两点坐标传入材质。
setab即为将y=ax+b形式的a,b传入，并指明a是否有意义，因为当直线形式为x=某数字时，a无意义。
具体计算如下：
void Calculate() ｛ wpLeft = portTrans.TransformPoint (new Vector3 (-10f, 0f, 0f));//porttrans为横线中心trans wpRight = portTrans.TransformPoint (new Vector3 (10f, 0f, 0f)); vpLeft = mainCamera.WorldToViewportPoint (wpLeft); vpRight = mainCamera.WorldToViewportPoint (wpRight); if (vpLeft.x != vpRight.x) ｛ va = (vpRight.y - vpLeft.y) / (vpRight.x - vpLeft.x); vb = vpLeft.y - vpLeft.x * va; wb = wpLeft.y - wpLeft.x * va; hasA = 1f; ｝ else ｛ va = vb = hasA = 0f; ｝ ｝ void SetMaterial() ｛ grayEffect.SetVector (vpLeft, vpRight); grayEffect.SetAB (va,vb,hasA); ｝
shader就是一个转彩色为灰度的shader，增加了判断片原位于哪个区域的功能，判断区域的代码可以根据需求更改
Shader "Custom/Tint"
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Properties
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_MainTex ("", any) = ""
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_Line ("line", Vector) = (0,0,0,0)
_ab ("ab", Vector) = (0,0,0)
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CGINCLUDE
#include "UnityCG.cginc"
struct
v2f
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float4 pos : SV_POSITION;
float3 wPos : TEXCOORD1;
float2 uv : TEXCOORD0;
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sampler2D _MainTex;
float4 _Line;
float3 _ab;
float4 TintColour;
v2f vert( appdata_img v )
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v2f o = (v2f)0;
o.pos = mul(UNITY_MATRIX_MVP, v.vertex);
o.wPos = v.vertex;
o.uv = v.texcoord;
return
o;
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float4 frag(v2f input) : SV_Target
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float4 c = tex2D(_MainTex, input.uv);
bool
isGray = false;
if(_ab.z==0)
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if(_Line.y>_Line.w&&input.wPos.x>_Line.x)
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isGray = true;
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if(_Line.y<_Line.w&&input.wPos.x<_Line.x)
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isGray = true;
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else
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float
ey = _ab.x*input.wPos.x + _ab.y;
if(_Line.x<_Line.z&&input.wPos.y>ey)
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isGray = true;
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if(_Line.x>_Line.z&&input.wPos.y<ey)
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isGray = true;
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if(isGray)
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float
gray = dot(c.xyz, float3(0.299, 0.587, 0.114));
c.xyz = float3(gray,gray,gray);
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dot(c.xyz, float3(0.299, 0.587, 0.114))就是把彩色信息转化成灰度信息的数学公式，即为x,y,z对应乘0.299 0.587,0.114
优化shader，去除if语句
float4 c = tex2D(_MainTex, input.uv); float ey = _ab.x*input.wPos.x + _ab.y; bool b1 = _Line.y>_Line.w&&input.wPos.x>_Line.x; bool b2 = _Line.y<_Line.w&&input.wPos.x<_Line.x; bool b3 = _Line.x<_Line.z&&input.wPos.y>ey; bool b4 = _Line.x>_Line.z&&input.wPos.y<ey; bool a1 = (_ab.z==0)&&(b1||b2); bool a2 = (_ab.z!=0)&&(b3||b4); bool d = a1||a2; float gray = dot(c.xyz, float3(0.299, 0.587, 0.114)); c.xyz *= (!d); c.xyz += float3(gray,gray,gray)*d;
这样就可以对屏幕特定部分进行后期特效处理了。
来自：https://blog.csdn.net/juan_bo/article/details/52291166