TrimGear Plugin for X-Plane 12

TrimGear is an X-Plane 12 plugin that addresses hardware limitations when trimming simulated aircraft. Not all joystick trim wheels are geared appropriately for X-Plane's built-in trim commands. This plugin allows users to gear up or gear down their trim sensitivity to match their specific hardware.

Features

• Custom Trim Commands: 6 new commands for geared trim control

  • trimgear/pitch_trim_up - Pitch trim up with gear
  • trimgear/pitch_trim_down - Pitch trim down with gear
  • trimgear/roll_trim_left - Roll trim left with gear
  • trimgear/roll_trim_right - Roll trim right with gear
  • trimgear/rudder_trim_left - Rudder trim left with gear
  • trimgear/rudder_trim_right - Rudder trim right with gear

• Configurable Gear Settings: 9 predefined gear ratios

  • 0.001, 0.005, 0.01, 0.015, 0.02, 0.025, 0.03, 0.035, 0.04

• Per-Aircraft Configuration: Settings are automatically saved and loaded for each aircraft

• Plugin Menu: Easy gear selection through X-Plane's plugin menu system

Code Structure

Core Components

• src/trimgear.cpp - Main plugin entry point

  • Implements X-Plane plugin callbacks (XPluginStart, XPluginStop, etc.)
  • Manages custom command creation and registration
  • Handles menu system creation and interaction
  • Coordinates between config and trim controller components

• src/trim_controller.h/cpp - Trim adjustment logic

  • Manages X-Plane dataref access for trim controls
  • Implements gear-based trim adjustments
  • Handles three trim axes: pitch, roll, rudder
  • Uses datarefs: sim/flightmodel/controls/elv_trim, ail_trim, rud_trim

• src/config.h/cpp - Configuration management

  • Loads and saves per-aircraft gear settings
  • Manages TrimGear.cfg files in aircraft directories
  • Uses XPLMGetNthAircraftModel(0, ...) to locate current aircraft
  • Handles configuration parsing and file I/O

• src/constants.h - Shared constants and enums

  • Defines gear setting values and menu item IDs
  • Contains trim axis enumeration
  • Buffer size constants for X-Plane API calls

Architecture

The plugin follows a modular design:

1. Plugin Layer (trimgear.cpp) - Interfaces with X-Plane SDK
2. Controller Layer (trim_controller) - Business logic for trim adjustments
3. Configuration Layer (config) - Persistent storage management
4. Constants Layer (constants) - Shared definitions

Building

Prerequisites

• CMake 3.16 or higher
• C++17 compatible compiler
• X-Plane 12 SDK

Quick Start (Recommended)

For first-time setup and building:

# Linux/Mac
./build-all.sh

# Windows
build-all.bat

These scripts will automatically download the X-Plane SDK, build the plugin, and provide installation instructions.

Manual Setup & Build

Setup SDK

Option 1: Use setup scripts:

# Linux/Mac
./setup-sdk.sh

# Windows  
setup-sdk.bat

Option 2: Manual setup:

1. Download the X-Plane SDK from developer.x-plane.com
2. Extract to SDK/ folder in project directory
3. Alternatively, set XPLANE_SDK_PATH environment variable

Build Commands

# Quick build (debug)
./build.sh

# Release build with package
./build.sh release

# Windows
build.bat
build.bat release

# Manual CMake (advanced)
mkdir build && cd build
cmake ..
cmake --build .
cmake --build . --target package

Platform-Specific Outputs

• Windows: build/TrimGear/win.xpl
• macOS: build/TrimGear/mac.xpl (Universal Binary)
• Linux: build/TrimGear/lin.xpl

Installation

1. Build the plugin following the instructions above
2. Copy the entire TrimGear folder to your X-Plane Resources/plugins/ directory
3. Restart X-Plane

Directory Structure

X-Plane 12/
└── Resources/
    └── plugins/
        └── TrimGear/
            └── win.xpl (or mac.xpl/lin.xpl)

Usage

Basic Operation

1. Assign Commands: In X-Plane's joystick settings, assign the TrimGear commands to your trim controls:

   • trimgear/pitch_trim_up
   • trimgear/pitch_trim_down
   • trimgear/roll_trim_left
   • trimgear/roll_trim_right
   • trimgear/rudder_trim_left
   • trimgear/rudder_trim_right

2. Adjust Gear Settings: Use the plugin menu (Plugins > TrimGear) to select appropriate gear ratios for each trim axis

3. Per-Aircraft Settings: Gear settings are automatically saved for each aircraft in a TrimGear.cfg file

Menu System

The plugin menu provides:

• Reload Configuration: Manually reload settings for current aircraft
• Pitch Trim Gear: 9 radio button options (0.001 to 0.04)
• Roll Trim Gear: 9 radio button options (0.001 to 0.04)
• Rudder Trim Gear: 9 radio button options (0.001 to 0.04)

Configuration Files

Configuration files are automatically created in each aircraft's directory as TrimGear.cfg:

# TrimGear Configuration File
# Gear settings index (0-8) corresponding to values:
# 0=0.001, 1=0.005, 2=0.01, 3=0.015, 4=0.02, 5=0.025, 6=0.03, 7=0.035, 8=0.04

pitch_gear=2
roll_gear=2  
rudder_gear=2

Troubleshooting

Common Issues

1. Plugin Not Loading

   • Check Log.txt for error messages
   • Verify SDK installation and platform-specific libraries
   • Ensure plugin is in correct directory structure

2. Commands Not Working

   • Verify commands are properly assigned in X-Plane joystick settings
   • Check that trim datarefs are available for current aircraft
   • Review Log.txt for dataref errors

3. Configuration Not Saving

   • Check aircraft directory permissions
   • Verify aircraft path detection is working
   • Look for filesystem errors in Log.txt

Debug Information

The plugin writes detailed logging to X-Plane's Log.txt file with prefix "TrimGear:". Common log messages include:

• Plugin initialization status
• Dataref discovery results
• Configuration loading/saving operations
• Gear setting changes
• Trim adjustment actions

Requirements

• X-Plane 12
• Compatible joystick/trim hardware
• Windows 10+, macOS 10.14+, or Linux with X11