Simple hold-to-zoom feature for Starfield

Overview • Features • Installation • Usage • Configuration • Building • License

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Overview

StarZoom is a native SFSE plugin for Starfield, built on CommonLibSF. Hold a key (keyboard or gamepad) in first- or third-person view and the camera's FOV smoothly zooms in; release it and the FOV eases back to normal.

It drives the game's own fFPWorldFOV:Camera/fTPWorldFOV:Camera settings (via RE::INIPrefSettingCollection/RE::INISettingCollection) — the same values the renderer itself reads for first-/third-person FOV — rather than touching any camera/scene-graph memory directly. See How it works below. The same mechanism optionally scales fMouseHeadingSensitivity:Controls alongside it, so aim doesn't feel twitchy at a narrower zoomed-in FOV.

By using this project you agree to comply with the CommonLibSF license, which is GPL-3.0-or-later WITH Modding Exception AND GPL-3.0 Linking Exception (with Corresponding Source). In short: if you distribute a compiled binary linked against CommonLibSF, you must also make the corresponding source available.

Features

• Per-view toggle — zoom in first person only, third person only, or both.
• Smooth ease in/out — a smoothstep transition (zero velocity at both ends) instead of an abrupt cut, so the zoom never jolts when the hotkey is pressed, released, or tapped quickly mid-transition.
• Keyboard hotkey — any virtual-key code, configurable.
• Gamepad support — any XInput button bitmask also triggers the zoom (default: Left Stick button / LSB), independently of the keyboard hotkey.
• Config-driven — target FOV and transition speed are both adjustable without recompiling.
• Mouse sensitivity compensation — optionally scales sensitivity down while zoomed, in proportion to how much the FOV has narrowed, so aim doesn't feel twitchy at low zoom FOVs.
• Hot reload — press a key (default F3) in-game to apply StarZoom.ini edits without restarting.

Installation

1. Install SFSE, Address Library for SFSE Plugins and StarZoom.
2. Copy StarZoom.dll and StarZoom.ini into Data\SFSE\Plugins\ in your Starfield install folder.
3. Launch the game via sfse_loader.exe.

Usage

Hold the configured hotkey (default: C on keyboard, LSB/Left Stick button on an XInput gamepad) in first- or third-person view to zoom in. Release it to ease back to the normal FOV.

Configuration

Edit StarZoom.ini next to the DLL (created with defaults on first launch if missing):

Key	Default	Description
Hotkey	67	Virtual-key code of the hold-to-zoom key (67 = C)
GamepadButton	64	XInput button bitmask that also holds-to-zoom (64 = Left Stick button / LSB; 0 disables)
ZoomFOV	60.0	FOV in degrees while the hotkey is held
ViewMode	2	Which view(s) the hotkey zooms in (0 = first person only, 1 = third person only, 2 = both)
SmoothSpeed	8.0	Ease-in/ease-out speed for the zoom transition (higher = snappier)
ReloadKey	114	Virtual-key code that reloads this file without restarting the game (114 = F3)
ScaleMouseSensitivity	1	Whether to scale mouse sensitivity down while zoomed (1 = on, 0 = off)
SensitivityExponent	2.5	How aggressively sensitivity is cut at a given zoom level (only while ScaleMouseSensitivity=1); 1.0 scales linearly with FOV, higher cuts harder

Press the reload key (default F3) in-game after editing StarZoom.ini to apply changes immediately — no restart needed.

For a full list of decimal keyboard and gamepad (XInput) codes, see the Keybind Reference PDF in the Files tab on this mod's Nexus page.

Building

Requirements

• XMake 3.0.0+
• C++23 compiler: MSVC (Build Tools for Visual Studio, no full IDE required) or Clang-CL

Dependencies

lib/commonlibsf (and its own nested lib/commonlib-shared dependency) is a git submodule. Fetch it with:

git submodule update --init --recursive

Build

xmake build

This produces StarZoom.dll under build/windows/x64/....

Visual Studio project (optional)

xmake project -k vsxmake

generates a vsxmakeXXXX/ solution if you'd rather build/debug from the Visual Studio IDE.

Project Structure

├── src/
│   ├── PCH.h                 Precompiled header (CommonLibSF + STL includes)
│   ├── Plugin.cpp            SFSE entry point (SFSE_PLUGIN_LOAD)
│   ├── Config.h / .cpp       StarZoom.ini load / defaults
│   ├── Hooks.h / .cpp        DXGI swapchain Present hook install
│   ├── Input.h / .cpp        Keyboard + XInput hotkey polling
│   └── FOVController.h / .cpp   Per-frame FOV transition + INI setting write
├── dist/StarZoom.ini         Default config, shipped alongside the DLL
└── lib/commonlibsf/          CommonLibSF (git submodule)

How it works

StarZoom IAT-hooks the game's own import of CreateDXGIFactory2 (the standard D3D12 bootstrap call) as a trigger to check RE::CreationRendererPrivate::Renderer's own DXGI factory pointer — a CommonLibSF-exposed, Address-Library-resolved pointer into the game's renderer, and the actual source of truth. Once that pointer reports a real factory, StarZoom hooks IDXGIFactory2::CreateSwapChainForHwnd on it to catch the game's real swapchain the moment it's created, then hooks that swapchain's Present for a per-frame callback. A background thread polls the same renderer pointer directly as a fallback, with no timeout, in case the import hook can't attach on a given Starfield build. See the comments in Hooks.cpp for more detail.

License

This project is licensed under GPL-3.0-or-later WITH Modding Exception AND GPL-3.0 Linking Exception (with Corresponding Source).