Hi Guys,
So I’m in the process of porting a game from Unreal Engine 2 to UE4. I soon found out that all my materials
get default roughness of 0.5 and specularity of 0.5, which makes everything look very shiny. After some reading up
I found there existed a material property matrix in previous editions of UE4. However, it is disabled by by the developers
due to dependencies with the rendering thread. However, editing all these materials by hand is not very viable,
therefore I tried to find a way to bring this function back in Unreal Engine 4.
**Disclaimer: This tutorial involves editing the source code of UE4. I’m not responsible for any crashes or problems
this may cause. Proceed carefully and at your own risk.
Note: In this tutorial I’m working with UE4 4.19.2**
Step1: Clone UE4 from Github and follow the instructions:
https://github.com/EpicGames/UnrealEngine
Build the Engine once without changing anything to make sure everything works.
Step 2:
Open up visual studio and type “propertymatrix” in the top left corner of the Solution Explorer:
https://i.imgur.com/xy693xM.png
Select the ExecutePropertyMatrix() function under AssetContextMenu.cpp and open it.
Step 3:
Search for “bcanusepropertymatrix” until you land at this section of the code:
https://i.imgur.com/XJhTyXf.png
Step 4:
Change the bCanUsePropertyMatrix = false to true under the // Materials comment, around line 487.
https://i.imgur.com/dKjwxQd.png
Step 5:
Hit Build (F7) and go for a walk. Take a coffee or whatever, this is gonna take a while.
Step 6:
In your project, select the materials you want to edit, go to Asset Actions > Bulk Edit Via Property Matrix and it’s back 
https://i.imgur.com/Isuql0E.png