# What should I do if I want to know definition of specular?

**URL:** <https://forums.unrealengine.com/t/what-should-i-do-if-i-want-to-know-definition-of-specular/399147>\
**Category:** Rendering\
**Tags:** metallic, source, unreal-engine, specular, question\
**Created:** [June 23, 2017, 2:30am UTC](https://forums.unrealengine.com/t/what-should-i-do-if-i-want-to-know-definition-of-specular/399147 "2017-06-23T02:30:52Z")\
**Posts on this page:** 2\
**Page:** 1

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**Author:** ![anonymous\_user\_8ec418d71](https://d3kjluh73b9h9o.cloudfront.net/original/4X/2/8/5/28502927f1d97ba1051b3b47ccfe17233bf41ef0.png) [@anonymous\_user\_8ec418d71](https://forums.unrealengine.com/u/anonymous_user_8ec418d71)\
**Post date:** [June 23, 2017, 2:30am UTC](https://forums.unrealengine.com/t/what-should-i-do-if-i-want-to-know-definition-of-specular/399147/1 "2017-06-23T02:30:52Z")

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Once a day, I want to make sure that what our team are rendering looks real.  
So we want to calculate out the values we should use in UE4 about our material (a kind of oil paint) through an experiment.  
These values are metallic, basecolor, selfcolor, specular and roughness.  
Before we do the experiment, we need to know the definition about them, specially for specular. But I could not find result in Documents page.  
I tried to fetch the source code from github. To a Linux system.  
I searched for keyword “material” in the filenames using “find | grep material”, the results are:

./Engine/Plugins/Editor/USDImporter/Source/ThirdParty/USD/include/pxr/usd/usdShade/material.h

./Engine/Source/ThirdParty/FBX/2017.0.1/include/fbxsdk/utils/fbxmaterialconverter.h

./Engine/Source/ThirdParty/FBX/2017.0.1/include/fbxsdk/scene/shading/fbxsurfacematerial.h

./Engine/Source/ThirdParty/FBX/2016.1.1/include/fbxsdk/utils/fbxmaterialconverter.h

./Engine/Source/ThirdParty/FBX/2016.1.1/include/fbxsdk/scene/shading/fbxsurfacematerial.h

./Engine/Documentation/Source/Shared/Tutorials/InStaticMeshEditorTutorial/Images/materials.png

I cannot find any .c .cpp or .cxx files, what should I do if I want to see the functions which mix the input specular value, the input metallic value, the basecolor … to the result luminance or graylevel of the material?  
Any one help us?

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**Author:** ![redbox](https://d3kjluh73b9h9o.cloudfront.net/original/4X/2/8/5/28502927f1d97ba1051b3b47ccfe17233bf41ef0.png) [@redbox](https://forums.unrealengine.com/u/redbox)\
**Post date:** [June 23, 2017, 3:24am UTC](https://forums.unrealengine.com/t/what-should-i-do-if-i-want-to-know-definition-of-specular/399147/2 "2017-06-23T03:24:54Z")

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You should try to explore “Shaders” folder, and some documentation 😃

> **[Physically Based Materials](https://docs.unrealengine.com/4.27/en-US/RenderingAndGraphics/Materials/PhysicallyBased/)**
>
> An overview of the primary Material inputs and how best to use them.