title: ue4-shader-自定义shader代码hlsl
categories: UnrealEngine4
tags: [ue4, shader, hlsl, custom]
date: 2019-05-01 00:14:31
comments: false

ue4-shader-自定义shader代码hlsl.
tips: 相关测试在 CustomNode 目录下

自定义表达式节点

• 官方文档: https://docs.unrealengine.com/en-us/Engine/Rendering/Materials/ExpressionReference/Custom
• How to use HLSL and UE4. Introduction (边缘检测 示例) - https://www.parallelcube.com/2017/12/02/hlsl-introduction/

1. 右键新建一个 custom 节点

   

2. 加入 hlsl 代码, 修改相关参数.

   

   具体代码

   float3 blur = Texture2DSample(In, InSampler, UV);
   
   for (int i = 0; i < r; i++)
   {
   
     blur += Texture2DSample(In, InSampler, UV + float2(i * dist, 0));
     blur += Texture2DSample(In, InSampler, UV - float2(i * dist, 0));
   
   }
   
   for (int j = 0; j < r; j++)
   { 
   
     blur += Texture2DSample(In, InSampler, UV + float2(0, j * dist));
     blur += Texture2DSample(In, InSampler, UV - float2(0, j * dist));
   
   }
   
   blur /= 2*(2*r)+1;
   return blur;
   

   这里有几个需要注意的地方:

   1. 参数命名和hlsl代码中的必须完全一致, 大小写敏感
   2. Texture2DSample 中的第二个参数 InSampler 是与 In 相关的, 必须按照这样的写法来写. 输入贴图参数名是 XXX, 那么第二个参数就是 XXXSampler
   3. Texture2DSample 中的第一个参数 In 是一个 TextureObject, 而不是 TextureSample. 输入传入的是是一个 TextureSample, 会报错: undeclared identifier 'TexSampler'

踩坑: 报错 undeclared identifier 'TexSampler'

传入的参数错误, 应该传入一个 TextureObject, 而不是 TextureSample.

• https://answers.unrealengine.com/questions/541164/code-from-the-docs-doesnt-work.html

再来一波边缘检测 - Sobel 算子