nexus-gamesync

Native game-lighting capture shims for Nexus's Game Sync mode. These DLLs impersonate vendor RGB SDKs so that games hand their lighting to Nexus, which then renders it on the user's own hardware.

Windows-only. GSI (game-state integration) is a separate, service-side mechanism and does not live here.

What it does

Three shims impersonate three vendor SDKs. Each is a drop-in replacement loaded by bare name (from System32 / SysWOW64) in place of the real vendor DLL; it implements the SDK surface, captures the game's lighting, and forwards it to the local Nexus service. All three share one forwarding worker (src/forward.c): a thread + WinHTTP that fetches the pair token from /pair, then POSTs frame JSON to http://127.0.0.1:9400/lighting/game-sync/frame (coalesced to the service render rate). Colours go on the wire as COLORREF 0x00BBGGRR.

Shim	DLL(s)	Vendor SDK	ABI
Razer Chroma	RzChromaSDK64.dll / RzChromatic64.dll (x64), RzChromaSDK.dll / RzChromatic.dll (x86)	Razer Chroma	undecorated, GUID effect ids
Alienware/Dell LightFX	LightFX.dll	Dell LightFX 2.0	__stdcall, LFX_RESULT
Logitech	LogitechLedEnginesWrapper.dll / LogitechLed.dll	Logitech Gaming LED	__cdecl, bool

Capture / commit model (differs per SDK)

• Chroma - games either create a few keyboard effects once (colours baked in) then animate by SetEffect(id) cycling between them (Cyberpunk), or re-create the effect every frame and never SetEffect (Dead Cells). Grids are stored by effect id at create time and the active grid is forwarded on BOTH CreateKeyboardEffect and SetEffect. Both the 6x22 and 8x24 keyboard grids forward on the wire as effect CHROMA_CUSTOM (the service treats both sizes identically; there is no distinct CHROMA_CUSTOM2 wire effect).
• LightFX - staged state since the last LFX_Reset is committed on LFX_Update. LFX_SetLightColor / LFX_Light(mask,rgb) only stage; LFX_Update forwards one representative colour (CHROMA_STATIC 1x1).
• Logitech - no commit call; each set-call IS the frame. LogiLedSetLighting forwards a solid (CHROMA_STATIC 1x1); LogiLedSetLightingFromBitmap forwards the 21x6 BGRA bitmap as a CHROMA_CUSTOM 6x21 grid. Per-key set-calls no-op.

Layout

• src/forward.c / src/forward.h - shared forwarding worker (token, WinHTTP, coalescing, app-title sanitize, frame JSON). Each shim links it.
• src/rzchroma.c / .def / .rc - Razer Chroma shim (18 exports).
• src/lightfx.c / .def / .rc - LightFX shim (19 exports).
• src/logiled.c / .def / .rc - Logitech shim (30 exports, the official set).
• build.bat - x64 MSVC build of all three shims -> dist/.
• build32.bat - x86 MSVC build of all three shims -> dist/x86/.
• build32dbg.bat - x86 debug Chroma build with /DSHIM_LOG.
• test/ - dev harnesses (loadtest.c LightFX+Logitech load/forward; selftest_fwd.c / editortest.c Chroma; modlist.c 32-bit module enumerator).
• THIRD-PARTY.md - MIT attribution for Aurora-Wrappers + vendor-header notes.

Build

Requires MSVC (VS 2022 Build Tools). Run build.bat (x64) and build32.bat (x86) - 32-bit games load the x86 DLLs from SysWOW64. x64 DLLs land in dist/; x86 DLLs land in dist/x86/ (LightFX/Logitech share their names across arches, so the arches are kept in separate dirs). The Chroma DLLs ship under two names each because which one a game's editor lib loads is build-specific.

Install models

• System-wide (Model A, target): the Nexus installer places the DLLs in System32/SysWOW64 so any game loads them with zero per-game setup.
• Per-game (fallback): drop the DLLs next to a game's executable.

Legal

Clean-room reimplementations of the documented SDK export surfaces; they link no vendor code and redistribute no vendor headers. Razer Chroma, Alienware/Dell LightFX and Logitech are trademarks of their respective owners; this project is not affiliated with or endorsed by any of them. See THIRD-PARTY.md for attribution.

License

nexus-gamesync is licensed under the GNU Affero General Public License v3.0 (AGPL-3.0); see LICENSE for the full text. Contributions are covered by CLA.md - see CONTRIBUTING.md.

Copyright (C) 2026 Hello Nexus