OpenGL

OpenGL visualization driver is normally tied with a Geant4 GUI, and is the default driver in Geant4 if no driver is specified. Qt base GUI provides most controls of the viewer. It is my default choice for Geant4 visualization on macOS.

However, it is hard to use this driver in a Geant4 installation in a container, which may not even have a GUI. In such a case, there are two options. One is to use a combination of ATree, VRML2FILE, and TSG_FILE to cover everything that OpenGL with the Qt base GUI can do. The other is to generate HepRepFiles, which can be visualized using HepRApp offline. The latter is almost as powerful as the Qt based OpenGL.

Animation Example Code

// only "rich" trajectories contain time information
/vis/scene/add/trajectories rich
// time interval needs to be set with one of the trajectory models
/vis/modeling/trajectories/create/drawByParticleID
/vis/modeling/trajectories/drawByParticleID-0/default/setTimeSliceInterval 0.01 ns
// let the particle go
/run/beamOn
// set start time and a time window after the start time
/vis/viewer/set/timeWindow/startTime 0 ns 0.05 ns
// save the view to a file, g4_00.g4view
/vis/viewer/save
// save next view to a file, g4_01.g4view
/vis/viewer/set/timeWindow/startTime 1 ns 0.05 ns
/vis/viewer/save
// ...
// change all views together and create a lot of G4OpenGL_viewer-0_????.jpg
/vis/viewer/interpolate ! ! ! ! export

One can create animation using the jpg files exported from Geant4:

ffmpeg -i "G4OpenGL_viewer-0_%4d.jpg" -y animation.gif