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Dumiatis
New Participant
January 31, 2022
Solved

Is there a way in Unreal Engine to pre cache shaders for a given level.

  • January 31, 2022
  • 3 replies
  • 5632 views


I made a Quest 2 VR experience for a client. There are points in the experience where there are negative framerate spikes. I found out that the spikes are when shaders are first seen in a given level. Is there a way to pre cache the shaders?

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    Best answer by Dumiatis

    Thanks! Probably exactly what I wanted. 

    I followed the instructions to the letter in the video, but unfortunately it didn't create the PSO files. I saw in the comments that Vulcan seemed to be problematic with this, which is what I am using. But still storing this info away in case it's useful in the future. 

    3 replies

    Anonymous
    February 1, 2022

    Yes there is something like that:
    https://docs.unrealengine.com/4.26/en-US/ProgrammingAndScripting/Rendering/FShaderCache/
    https://answers.unrealengine.com/questions/715197/using-fshadercache-on-gearvr.html 

    Also maybe this is relevant:
    https://www.youtube.com/watch?v=0tzrsEm6V9Q
    And this:

     


    LET ME KNOW if it helped!

      DumiatisAuthorAnswer
      New Participant
      February 2, 2022

      Thanks! Probably exactly what I wanted. 

      I followed the instructions to the letter in the video, but unfortunately it didn't create the PSO files. I saw in the comments that Vulcan seemed to be problematic with this, which is what I am using. But still storing this info away in case it's useful in the future. 

      CarpetFace
      CarpetFace
      Inspiring
      February 6, 2022

      I have not tried the PSO solution yet, thinking that I'd use that only for shipping builds.  But what I still did anyways was to have a warmup phase during the initial load where I basically just put everything that caused a hitch while everything was still faded out black.  This works pretty well and hasn't been too difficult to setup and maintain.  I also now have the option to just not do the PSO step, as doing so will now only speed up the initial load.  So unless my boot time gets too bad, I might just skip it.  

       

      It does make me wonder why UE doesn't just do that automatically by default.  Is there some advantage to lazily creating the shader cache?  If the alternative is a runtime hitch during gameplay, that seems like a very poor design decision, especially for VR apps, so there must be some downside that I am missing?

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