We are getting some crashes from users during swap chain initialisation. We assume it’s because AMD’s Fidelity FX Swap Chain feature is the cause as it is enabled by default.
So we’d like to toggle this feature only when the user enables the FSR mode in our game.
For this we need to change the related cvar (r.FidelityFX.FI.OverrideSwapChainDX12) from the in-game setting and upon restart be ready during
SCOPED_BOOT_TIMING("LoadModulesForProject(ELoadingPhase::PostSplashScreen)");inside
FEngineLoop::PreInitPreStartupScreenwhich is too early for our custom GameUserSettings which do normally initialise cvars for us.
This brought us to the general question of this post:
What is Epic’s suggested way for changing and storing cvars during runtime for the next restart when game user settings are not applicable?
I figured the Scalability system starts very early for instance. But it does not set cvars directly but works by reading vars from the GameUserSettings ini and afterwards applying these to the actual cvars through code.
Does this mean the suggested way is to create custom code in a similar fashion? Or are there some onboard methods we could/should use?
For our particular use case we successfully tested modifying the FSR plug-in code by applying this same principle. Though it feels bit awkward to write custom code for this general purpose.
I’m aware of these posts
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This seems to work:
FConfigFile* ConfigFile = GConfig->FindConfigFile(GEngineIni); ConfigFile->bCanSaveAllSections = true; GConfig->SetInt(TEXT("/Script/FFXFSR3Settings.FFXFSR3Settings"), TEXT("r.FidelityFX.FI.OverrideSwapChainDX12"), FSREnabled, GEngineIni); GConfig->Flush(false, GEngineIni);But from the other posts it sounds like this is not what Epic would suggest to do.
Any clarification appreciated.
Regards