Input Flow Debugger

Unreal UI has many layers of input routing and focus management that can be difficult to visualize and debug. This plugin provides an in-game overlay and editor tools to help developers understand and troubleshoot input flow, navigation, and focus behavior in Unreal Engine 5 projects. Additionally, the tool provides the ability to inspect and modify MVVM ViewModels at runtime.

This is intended to be a tool in the toolbox in addition to the WidgetReflector and other built-in debugging tools.

Dependencies

• Created based on vanilla Unreal Engine 5.6, compatibility with other versions is not guaranteed. Pull requests for other versions are welcome.
• Enhanced Input (Optional, but required for Enhanced Input inspection features)
• CommonUI (Optional, but required for ActivatableWidget hierarchy features)
• ModelViewViewModel (Optional, but required for ViewModel inspection features)

Features

• Navigation Simulation ("Nav Spider"): Visualizes where navigation input (D-Pad/Arrow Keys) will go next, identifying explicit rules, boundary stops, and wrap behavior.
• Visual Focus History: Track widget focus changes over time with a visual trail on screen.
• Input Event Logging: Real-time log of Slate input events (Key Down, Click, Hover, Focus) with rich text links to open the specific widget asset in the Editor.
• Enhanced Input Inspector: Live view of active Contexts, Actions, Trigger states, and Modifiers.
• CommonUI Integration: Visualizes the Activatable Widget stack/queue and identifies the current Input Routing Leaf.
• Draggable Overlay: In-game debug overlay with movable, resizable panels.
• Editor Dock Tab: Analyze input state without cluttering the game viewport using the dedicated Editor Tab.
• NEW: ViewModel Inspector: Read the live values of all ViewModels bound to widgets, set new values at runtime.

Installation

1. Copy the InputFlowDebugger folder into your project's Plugins directory.
2. Regenerate project files and compile.
3. Enable the plugin in Edit > Plugins.

Usage

In-Game Overlay

The debugger injects an overlay directly into the game viewport.

• Toggle Overlay: Use the console command InputFlow.Overlay 1 to enable and InputFlow.Overlay 0 to disable.

Editor Analyzer

For a static view or secondary monitor debugging:

1. Go to Tools > Debug > Input Flow Debugger.
2. Play in Editor (PIE) to populate the data.

Visual Guide

Navigation Simulation

The debugger draws splines indicating navigation flow:

• Orange: Normal navigation.
• Pink: Explicit navigation rule.
• Red: Navigation stop.
• Blue: Handled by container.

License

MIT License. Pull requests and contributions are welcome!