tomeichlersmith / ldmx-g4-vis

GDML-based Detector Visualization

g4-vis

Copied from geant4/examples/extendend/gdml/G01. Its README and History are included here for reference.

While loading the GDML file(s), the Geant4 messages are directed to gdml_parse.out and gdml_parse.err for later inspection.

Set Up

Container

The Dockerfile packaged here is useful for creating an image with this code and its dependencies built into it. It takes some time to build an image (since we have to build Geant4), but once Geant4 is built, re-building with only changes to this source code is relatively quick.

docker build . -t ldmx-g4-vis

Running is a bit more complicated since we want to share the display and the directory from which we are running. ldmx-g4-vis is a short shell script that does the correct mounting behavior. You could copy it to a directory in your PATH or just run it directly.

cp /path/to/ldmx-g4-vis/ldmx-g4-vis ~/.local/bin #for example
ldmx-g4-vis Detectors/data/ldmx-det-v14

Container-less

Install Geant4 with Qt

# Depedencies
sudo apt install \
  cmake \
  libxerces-c-dev \
  qtcreator \
  qtbase5-dev \
  qt5-qmake \
# Configuration
cd geant4
git fetch --tags upstream
git checkout v10.7.3
cmake -B build -S . \
  -DCMAKE_INSTALL_PREFIX=install \
  -DGEANT4_USE_GDML=ON \
  -DGEANT4_USE_QT=ON
# build
cd geant4/build
make -j2 install

Source the environment script

source /full/path/to/geant4/install/bin/geant4.sh

Build this library

cmake -B build -S .
cd build
make

Run from the directory where all the GDML files reside so that any cross referencing can be deduced. The env.sh scripts offers an example of shortening this call.

cd ldmx-sw/Detectors/data/ldmx-det-v14
/path/to/ldmx-g4-vis/build/load_gdml detector.gdml

Why

For those fluent with Geant4, you might wonder why we would have our own visualization tool when there already exists an example program that loads and visualizes GDML. There are a few cosmetic reasons for this.

1. We can redirect Geant4's logging and error messages into files so that they can be inspected more closely.
2. We can apply the VisAttributes as defined in our GDML auxilliary information.
3. We code in the OGL viewer instead of having the program call out to Geant4 macro file.

None of these are particularly necessary to view the LDMX GDML design, but having our own executable also gives us the ability to align it better with our workflow.