Ground Control II - Wireless Fix & Smooth Zoom

A fix for Ground Control II (2004) that:

1. Prevents crashes on startup with wireless USB devices
2. Adds smooth mouse wheel zoom with inertia

The Problem

Ground Control II has two issues:

• Crash on startup when wireless USB devices (keyboards, mice, controllers) are connected
• Jerky zoom - mouse wheel zoom is choppy with no smooth scrolling

Reference: PCGamingWiki - Ground Control II

The Solution

This fix provides a replacement dinput.dll that:

• Prevents the wireless device crash
• Adds smooth inertia-based zoom using mouse wheel

Installation

1. Download dinput.dll from Releases
2. Copy it to your Ground Control II game folder (where gcii.exe is located)
3. (Optional) Copy dinput_inertia.ini to customize zoom behavior
4. Play the game

To uninstall, simply delete dinput.dll from the game folder.

Mouse Wheel Zoom Configuration

The zoom behavior can be customized via dinput_inertia.ini in the game folder:

[Inertia]
Enabled=1           ; 1 = on, 0 = off
DecayRate=80        ; 1-100: how fast momentum decays (higher = faster stop)
Multiplier=200      ; 1-500: zoom speed per wheel tick (higher = faster)
InjectInterval=4    ; 0-500ms: delay between zoom steps (lower = smoother)
ReverseWheel=1      ; 1 = Starcraft 2 style, 0 = original behavior

If no INI file is present, sensible defaults are used.

Technical Details

Wireless Device Fix

The crash occurs in Windows' DirectInput library during HID device enumeration. This fix:

• Intercepts EnumDevicesA and returns only keyboard/mouse (avoids HID crash)
• Intercepts GetDeviceInfo (avoids a secondary crash)
• Forwards all other DirectInput calls to the real dinput.dll

Smooth Zoom

Ground Control II uses Page Up/Page Down for camera altitude but only checks wheel direction, not magnitude. This fix:

• Captures mouse wheel input and accumulates velocity with momentum
• Converts velocity to Page Up/Page Down key presses via DirectInput
• Injects keys at a configurable rate for smooth zooming

Building from Source

Requires Visual Studio Build Tools with C++ workload.

1. Open Developer Command Prompt for VS
2. Navigate to the source directory
3. Run:

   build.bat           # Debug build (with logging)
   build.bat release   # Release build (no logging)

Source Files

File	Description
dinput_impl.c	Main implementation
dinput_inertia.ini	Zoom configuration template
dinput.def	DLL export definitions
version.rc	Version resource (metadata)
build.bat	Portable build script

Debug Build

The debug build creates dinput_debug.log next to the game executable, useful for troubleshooting. The release build has no logging overhead.

Compatibility

• Game: Ground Control II (2004)
• OS: Windows 10/11
• Architecture: 32-bit (x86) - matches the game
• Game stores: GOG and Steam versions

License

MIT License - see LICENSE

Credits

• Mykola Nick Yakovliev
• Fix developed with assistance from Claude (Anthropic)