[DLSS-G] Add runtime gating of IDXGISwapChainProvider to prevent early PresentBefore hook

[torbjornsoderman]

We're integrating DLSS-G (DLSS Frame Generation) using the 4.0.2 version into a real-time Unreal Engine 5.5.4 game and encountering a critical issue:

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🔥 Issue Summary

When the DLSS-G plugin is loaded (even with all activation cvars set to 0), the Streamline framework (version v2.7.30.afa89bde) immediately registers a DXGI PresentBefore hook via IDXGISwapChainProvider.

This causes a GPU hang in packaged builds when startup movies (e.g., Bink) are playing — even though DLSS-G is disabled in all config cvars.

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🧪 Repro Conditions

• DLSS-G plugin is "Enabled": true in .uproject (required to cook shaders like FStreamlineVelocityCombineCS)

• DefaultEngine.ini has:

  r.Streamline.Enable=0
  r.Streamline.Load.DLSSG=0
  r.Streamline.DLSSG.Enable=0
  
  

  • Bink movie plugin plays a fullscreen startup movie
  • No DLSS-G features are initialized or used
  • On startup: GPU crash (device removed during early DXGI present)

  ✅ Expected Behavior

  If r.Streamline.Load.DLSSG=0, the DLSS-G module should not register any DXGI hooks during StartupModule() or plugin load time.

  This would allow us to:

  • Cook DLSS-G shaders
  • Delay plugin activation manually (e.g., after movie playback)
  • Avoid early DXGI interference

  🚧 Current Workarounds Attempted

  • Delayed LoadModuleChecked() → fails due to missing cooked shaders (requires "Enabled": true)
  • Runtime cvar toggling → DXGI hook already registered too early
  • Tried Optional: true and EnablePlugins.Add(...) — no effect
  • Full Streamline SDK integration → not applicable to DLSS-G (precompiled only)

  🧩 Suggested Solution

  Please consider exposing a cvar like: r.Streamline.DelayHookRegistrationUntilFirstPresent=1 or a deferred DXGI hook registration like:

  if (r.Streamline.Load.DLSSG != 0)
  {
      RegisterIDXGISwapChainProvider();
  }
  
  
  

Torbjörn Söderman Technical Director, GOALS