LatencyFleX Implementation Update (#183)v1.8.1-rc4

Main entry point for LatencyFlex was recently changed from
latencyflex_wine.dll to latencyflex_layer.dll to prepare library for
eventual windows release/to be more generic. This updates our
implementation to match, while still supporting the previous libraries
for existing users.

Co-authored-by: Kyle Gospodnetich <KyleGospo@users.noreply.github.com>

1 files changed, 41 insertions, 9 deletions

diff --git a/NorthstarDedicatedTest/latencyflex.cpp b/NorthstarDedicatedTest/latencyflex.cpp
index 4ac1c760..3e2cecd7 100644
--- a/NorthstarDedicatedTest/latencyflex.cpp
+++ b/NorthstarDedicatedTest/latencyflex.cpp
@@ -9,13 +9,19 @@ OnRenderStartType OnRenderStart;
 ConVar* Cvar_r_latencyflex;
 
 HMODULE m_lfxModule {};
-typedef void (*PFN_winelfx_WaitAndBeginFrame)();
-PFN_winelfx_WaitAndBeginFrame m_winelfx_WaitAndBeginFrame {};
+typedef void (*PFN_lfx_WaitAndBeginFrame)();
+PFN_lfx_WaitAndBeginFrame m_lfx_WaitAndBeginFrame {};
 
 void OnRenderStartHook()
 {
+	// Sleep before next frame as needed to reduce latency.
 	if (Cvar_r_latencyflex->GetInt())
-		m_winelfx_WaitAndBeginFrame();
+	{
+		if (m_lfx_WaitAndBeginFrame)
+		{
+			m_lfx_WaitAndBeginFrame();
+		}
+	}
 
 	OnRenderStart();
 }
@@ -25,17 +31,43 @@ void InitialiseLatencyFleX(HMODULE baseAddress)
 	// Connect to the LatencyFleX service
 	// LatencyFleX is an open source vendor agnostic replacement for Nvidia Reflex input latency reduction technology.
 	// https://ishitatsuyuki.github.io/post/latencyflex/
-	m_lfxModule = LoadLibraryA("latencyflex_wine.dll");
+	const auto lfxModuleName = "latencyflex_layer.dll";
+	const auto lfxModuleNameFallback = "latencyflex_wine.dll";
+	auto useFallbackEntrypoints = false;
+
+	// Load LatencyFleX library.
+	m_lfxModule = ::LoadLibraryA(lfxModuleName);
+	if (m_lfxModule == nullptr && ::GetLastError() == ERROR_MOD_NOT_FOUND)
+	{
+		spdlog::info("LFX: Primary LatencyFleX library not found, trying fallback.");
 
-	if (m_lfxModule == nullptr)
+		m_lfxModule = ::LoadLibraryA(lfxModuleNameFallback);
+		if (m_lfxModule == nullptr)
+		{
+			if (::GetLastError() == ERROR_MOD_NOT_FOUND)
+			{
+				spdlog::info("LFX: Fallback LatencyFleX library not found.");
+			}
+			else
+			{
+				spdlog::info("LFX: Error loading fallback LatencyFleX library - Code: {}", ::GetLastError());
+			}
+
+			return;
+		}
+
+		useFallbackEntrypoints = true;
+	}
+	else if (m_lfxModule == nullptr)
 	{
-		spdlog::info("Unable to load LatencyFleX library, LatencyFleX disabled.");
+		spdlog::info("LFX: Error loading primary LatencyFleX library - Code: {}", ::GetLastError());
 		return;
 	}
 
-	m_winelfx_WaitAndBeginFrame =
-		reinterpret_cast<PFN_winelfx_WaitAndBeginFrame>(reinterpret_cast<void*>(GetProcAddress(m_lfxModule, "winelfx_WaitAndBeginFrame")));
-	spdlog::info("LatencyFleX initialized.");
+	m_lfx_WaitAndBeginFrame = reinterpret_cast<PFN_lfx_WaitAndBeginFrame>(reinterpret_cast<void*>(
+		GetProcAddress(m_lfxModule, !useFallbackEntrypoints ? "lfx_WaitAndBeginFrame" : "winelfx_WaitAndBeginFrame")));
+
+	spdlog::info("LFX: Initialized.");
 
 	Cvar_r_latencyflex = new ConVar("r_latencyflex", "1", FCVAR_ARCHIVE, "Whether or not to use LatencyFleX input latency reduction.");