Building the PSO Cache

In order for the Pipeline State Object (PSO) caching system to function correctly, it has to map the requested Shaders to the Materials that requested them.  This is accomplished by using the ShaderPipelineCacheTools commandlet to build a file that contains this mapping information. In the following How-To, we will take a look at how to use the ShaderPipelineCacheTools commandlet to build the needed files.

Steps

1. First, on the root of your C drive, make a new folder called PSOCaching.

2. Next, open your UE4 project folder to the following location and look for the scl.csv file.
   ProjectName\Saved\Cooked\PlatfourmYouCookedFor\ProjectName\Metadata\PipelineCaches
   

   SCL_CSV_File_Location.png

   Click for full image.

   If you are working with Android, you will need to add the following to your AndroidEngine.ini file:

   [DevOptions.Shaders]
   NeedsShaderStableKeys=true

   If you do not have NeedsShaderStableKeys enabled, it will not create the scl.csv files in metadata needed to generate the stable.csv file later.

3. Copy the both scl.csv files that are in the Pipeline Caches folder into the PSOCaching folder that was created on the root of your C drive.

4. Next, copy the rec.upipelinecache file that was generated when the project was run on a target device to the PSOCaching folder that was created on the C drive.
   

5. To generate the needed files we will need to use UE4 commandlet function. To use the commandlet function, first open up the Engine\Binaries\Win64 folder and look for the UE4Editor-Cmd.exe file.
   

6. Right-click the UE4Editor-Cmd.exe file, and from the displayed list select the Create Shortcut option.

7. Move the newly created shortcut to the PSOCaching folder that was created on the root of your C drive.

8. Right-click UE4Editor-Cmd.exe shortcut, and from the displayed menu select the Properties option.

9. In the Target input, add the following command line parameters after the end of UE4Editor-Cmd.exe.
   

   ActionRPG -run=ShaderPipelineCacheTools expand C:/PSOCaching/*.rec.upipelinecache C:/PSOCaching/*.scl.csv ActionRPG_GLSL_ES3_1_ANDROID.stablepc.csv

10. Click OK to close the shortcut properties dialogue box and then double-click UE4Editor-Cmd.exe - Shortcut to run the commandlet.

11. Once the commandlet is finished running, a new file called stablepc.csv is created and placed in the PSOCaching folder that was created on the root of the C drive.
    

End Result

With the scl.csv and the rec.upipelinecache files now combined together to produce the stablepc.csv file, next we need to place the stablepc.csv file in a specific location so that it will be used when your UE4 project is being built..