Introduction

The G4Display module provides a Qt-based graphical user interface layer for controlling and interacting with Geant4 visualization from within GEMC. It is designed to expose common viewer controls (camera direction, lighting, scene style toggles, cutaway planes, etc.) through a set of QWidget-based panels.

The module assumes a running Geant4 UI session and communicates with it by sending visualization commands to G4UImanager. These commands are the same as would be used interactively in a Geant4 macro, but are generated in response to GUI events.

GEMC graphical interface with the Display page selected

GEMC scene decoration and annotation controls

Module structure

The module is primarily composed of:

G4Display : main widget that hosts visualization control tabs.
G4DisplayView : tab that provides camera, lighting, slice controls, and view toggles.
G4DisplayUtilities : tab with scene decoration and text controls.
G4SceneProperties : helper that generates Geant4 visualization commands for initial scene setup.
g4display options helpers (see g4display::defineOptions and related getters) used to map GOptions configuration into simple structs consumed by the GUI and scene initializers.

Verbosity and logging

Several classes in this module are built on top of GEMC base utilities that provide structured logging via GLogger. The logger name for this module is typically "g4display" (see G4DISPLAY_LOGGER).

The conventional meaning of the verbosity levels is:

Level 0 : high-level user-facing messages (major actions and state changes).
Level 1 : additional informational messages (configuration choices, derived parameters).
Level 2 : detailed informational messages (frequent GUI-driven updates, fine-grained state).
Debug : developer diagnostics (construction/destruction traces, command strings, internal decisions).

Typical usage

In a GEMC application, the GUI widget G4Display is instantiated with a shared GOptions instance and embedded into a parent window. Users interact with the GUI controls; the module translates those interactions into Geant4 visualization commands sent via G4UImanager.

The helper G4SceneProperties can be used during initialization to build a consistent default scene and viewer configuration from options.

Configuration

g4display::defineOptions() provides the following option groups:

g4view: driver, window dimensions and position, curve precision, background, and cloud density.
g4camera: initial camera theta and phi.
g4light: initial light-source theta and phi.
g4decoration: scale, axes, event ID, date, logos, and frame settings.
g4text: optional scene annotations.
dawn and useDawn: DAWN output view and enable switch.

The typed accessors getG4View(), getG4Camera(), getG4Light(), and getG4Decorations() project those option nodes into the structures used by the GUI and scene initializer.

Building and dependencies

This module depends on:

Qt6 (Widgets module)
Geant4 (UI and visualization)
GEMC core utilities (GOptions, GBase, GLogger, etc.)

Examples

The following example demonstrates how to create a minimal Geant4 visualization environment and optionally attach the G4Display GUI.

g4display_example_cc : Minimal G4Display GUI usage
Summary: create GOptions + logger, initialize G4VisExecutive, and build G4Display inside a Qt window.

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