FSR 4 Upscaling for Gunner, HEAT, PC!

AMD FSR 4.1 in GHPC. The game renders at a lower resolution and FSR rebuilds the full picture, so you get more frames and better anti-aliasing than the game's own. Cards without FSR 4 get FSR 3.1.

Reticles, bloom, depth of field and the rest of the effects are drawn after FSR at full resolution, so the sights stay sharp.

Warning

This is a janky mod. GHPC is Direct3D 11 and FSR 4 only runs on Direct3D 12, so the mod runs FSR on a second device next to the game's and passes the frame back and forth every frame. It's a hack and it might give you glitches, crashes or worse performance. I've only tested it on my own PC (RX 9070 XT at 4K). If it doesn't work on yours, delete the DLL and you're back to the normal game.

Installing it

1. Get MelonLoader 0.7.3 or newer into GHPC.
2. Download FSR4_<version>.zip from Releases.
3. Copy the Mods folder from the zip into the game folder, the one with GHPC.exe in it, so you end up with Mods\FSR4.dll.
4. Start the game. FSR is on straight away, in Quality mode.

Needs Windows 10 or 11 and a Direct3D 12 card. FSR 4 itself needs a Radeon RX 9000 (RDNA 4), anything else gets FSR 3.1. No other mods needed.

To remove it, delete Mods\FSR4.dll and the UserData\FSR4 folder.

Modes

Press F9 in game to step through them (Auto and Off are in the cycle too), or set one in the settings. The new mode shows at the top of the screen for a couple of seconds.

Mode	At 1080p renders at	At 4K renders at
NativeAA (FSR as anti-aliasing only)	1920x1080	3840x2160
Quality (default)	1280x720	2560x1440
Balanced	about 1130x635	about 2260x1270
Performance	960x540	1920x1080
UltraPerformance	640x360	1280x720
Auto	1920x1080 to 960x540	3840x2160 to 1920x1080

Auto moves the resolution to hold your target frame rate (90 by default), and only drops it when the graphics card is actually what's holding you back.

The mod also switches off a few of the game's cameras that render every frame for nothing (first-person, map, heat haze). Same picture, about 1 ms a frame back at 4K, and it works with FSR off too.

If FSR can't start, the mod says so in the MelonLoader console and the game carries on with its own anti-aliasing.

Frame generation

Off by default. Set FrameGeneration = true in the settings and AMD's frame generation puts a generated frame between every two real ones, so 80 real frames come out as about 160 on screen. It needs FSR on, any mode. On a Radeon RX 9000 it's FSR 4 frame generation, anything else gets FSR 3.1's.

• It costs a bit: about 7 % of your real frames on my PC, so expect a touch more input lag than the frame counter suggests.
• It only steps in when the game runs below half your monitor's refresh rate, above that there's nothing to gain.
• I run it with the game's vsync off and its frame cap at 90. That's the setup I've tested.
• The HUD stays sharp, but trees right next to the camera can smear a bit when you swing the view fast. That's the generated frame guessing, not much I can do about it.

Known limits

• The FSR 3.1 path has only been tested by forcing it on an FSR 4 card, and FSR 3.1 frame generation hasn't been run at all. If you're on something else, I'd like to hear how it goes.
• Trees are the most expensive thing in the sights and there's no free fix for them. Fewer pixels is what helps, which is what the modes are for.

Bugs

Open an issue with your graphics card, resolution and FSR mode, and attach MelonLoader\Latest.log from the game folder.

Settings

After the first start, UserData\MelonPreferences.cfg has an [FSR 4] section (close the game before editing it):

Setting	Values	Default
Enabled	true / false	true
Quality	NativeAA, Quality, Balanced, Performance, UltraPerformance, Auto	Quality
Sharpness	0 to 1	0.2
Target frame rate	Auto only, 0 is your display's refresh rate	90
Auto minimum scale	Auto only, 1.0 is full resolution	1.0
Auto maximum scale	Auto only, 2.0 is Performance	2.0
Cycle key	F1-F15, A-Z, 0-9 or None	F9
Show mode on screen	true / false	true
FrameGeneration	true / false	false

The camera switches are in [FSR4_Performance]: FpCameraIdle, FpCameraNoShadows, DistortionCameraForward and MapCameraIdle (on), InstancerCameraFilter (off, no measurable gain).

How it works (for devs)

Two halves: the C# mod hooks into Unity and GHPC, and a C++ bridge (native\bridge.cpp) runs FSR. The bridge and AMD's three DLLs are embedded in FSR4.dll and unpacked to UserData\FSR4 at start.

Where FSR sits in the frame. GHPC uses Unity's Post Processing Stack v2. While FSR is on, I force the main camera's PostProcessLayer to TAA and a Harmony transpiler on PostProcessLayer.Render swaps its two TAA calls (the jittered projection and TemporalAntialiasing.Render) for FSR's jitter and FSR's upscale. That way FSR gets the HDR colour before exposure, the real depth (ResolvedDepth) and the motion vectors, and everything after the TAA slot (the game's reticles and scope mask, depth of field, bloom, exposure, grain, grading) runs on FSR's full-size output. The player's own anti-aliasing setting is put back when FSR goes off.

Rendering below display size. The main camera gets a display-size render target of mine, and its camera.rect is shrunk to the render size only for the length of its render (OnPreCull to OnPostRender), so Unity and PPv2 size everything before the TAA slot to the render size. A presenter camera of mine then blits the final picture to the screen, before the first-person camera and the UI. The main camera can't render straight to the screen, cos Unity puts all of a frame's screen cameras in one buffer sized by the first of them, and a shrunk main camera makes that buffer small, so everything comes out blurry.

The D3D11 to D3D12 bridge. Unity calls into the bridge on the render thread through IssuePluginEvent. The bridge makes a D3D12 device on the same adapter as the game's D3D11 one (by LUID), and the two share the colour, depth, motion and output textures and two fences, one per direction. Each frame D3D11 copies the inputs and signals, the D3D12 queue waits on that, runs FSR and signals back, and D3D11 waits on that before reading the output. Three command allocator slots so neither side waits on the other longer than it has to. The bridge asks AMD's loader which upscaler versions the driver offers and takes FSR 4 when it's there, FSR 3.1 when it isn't.

The rest.

• Mip bias: log2(render / display) - 1 on the game's textures while FSR is on, UI, fonts and reticles left alone, everything put back on off.
• History resets come from the game's own view-change events (switching sights or cameras).
• Auto runs one FSR context with the dynamic resolution flag, so a change of scale doesn't reset the history.
• Guards: the transpiler checks the patched IL, and if a game update moves the code it hooks, or nothing gets upscaled, FSR switches off for the session. If the bridge hits an error, FSR stops and the game falls back to its own anti-aliasing.
• Frame generation: the bridge hooks the game's Present through its swap chain and runs AMD's frame generation by hand on its D3D12 device, then presents the generated frame and the real one through the game's own chain, paced to half the real interval. AMD's own frame generation swap chain is out, cos DXGI won't take a second flip chain on Unity's window. It gets the frame before the overlay UI as its hudless input, which is what keeps the compass tape from doubling.

Building from source

C# (.NET Framework 4.7.2) plus a C++ half in native\. You need the .NET SDK 6+, GHPC with MelonLoader, CMake and the Visual Studio 2022 C++ build tools, and AMD's amd_fidelityfx_loader_dx12.dll, amd_fidelityfx_upscaler_dx12.dll and amd_fidelityfx_framegeneration_dx12.dll from the FidelityFX SDK (Kits\FidelityFX\signedbin) in native\amd\ (or -p:FsrSdkBin=<folder>).

dotnet build -c Release -p:GameDir="<GHPC folder>\Bin"

The DLL ends up in bin\Release\FSR4.dll with the native bridge and AMD's DLLs embedded.

License

GPL-3.0. AMD's FidelityFX headers in native\ffx\ and the FSR DLLs are AMD's, under the MIT licence that comes with the FidelityFX SDK. FSR is AMD's, and this mod isn't made or endorsed by AMD.