LatencyFleX Implementation (#41)

* Adds LatencyFleX, an open source and vendor agnostic input latency reduction technology similar to Nvidia's Reflex. Currently only works on Linux via Wine/Proton, but future versions may support Windows as well. Falls back to doing nothing if LatencyFleX isn't available.

See here for more information:
https://ishitatsuyuki.github.io/post/latencyflex/

* Add the ability to toggle LatencyFlex on or off with a cvar.

1 files changed, 47 insertions, 0 deletions

diff --git a/NorthstarDedicatedTest/latencyflex.cpp b/NorthstarDedicatedTest/latencyflex.cpp
new file mode 100644
index 00000000..84b79d33
--- /dev/null
+++ b/NorthstarDedicatedTest/latencyflex.cpp
@@ -0,0 +1,47 @@
+#include "pch.h"
+#include "latencyflex.h"
+#include "hookutils.h"
+#include "dedicated.h"
+#include "convar.h"
+
+typedef void(*OnRenderStartType)();
+OnRenderStartType OnRenderStart;
+
+ConVar* Cvar_r_latencyflex;
+
+HMODULE m_lfxModule{};
+typedef void (*PFN_winelfx_WaitAndBeginFrame)();
+PFN_winelfx_WaitAndBeginFrame m_winelfx_WaitAndBeginFrame{};
+
+void OnRenderStartHook()
+{
+	if (Cvar_r_latencyflex->m_nValue)
+		m_winelfx_WaitAndBeginFrame();
+
+	OnRenderStart();
+}
+
+void InitialiseLatencyFleX(HMODULE baseAddress)
+{
+	if (IsDedicated())
+		return;
+
+	// 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");
+
+	if (m_lfxModule == nullptr)
+	{
+		spdlog::info("Unable to load LatencyFleX library, LatencyFleX disabled.");
+		return;
+	}
+
+	m_winelfx_WaitAndBeginFrame = reinterpret_cast<PFN_winelfx_WaitAndBeginFrame>(reinterpret_cast<void*>(GetProcAddress(m_lfxModule,"winelfx_WaitAndBeginFrame")));
+	spdlog::info("LatencyFleX initialized.");
+
+	Cvar_r_latencyflex = RegisterConVar("r_latencyflex", "1", FCVAR_ARCHIVE, "Whether or not to use LatencyFleX input latency reduction.");
+
+	HookEnabler hook;
+	ENABLER_CREATEHOOK(hook, (char*)baseAddress + 0x1952C0, &OnRenderStartHook, reinterpret_cast<LPVOID*>(&OnRenderStart));
+}
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