Running the event display DELGRA

General information

The DELPHI event display DELGRA is shipped as part of the DELPHI software stack. It is based on the PHIGS, an old 3d graphics standard. The current version has been migrated to open source software tools only. During this move the functionality had to be slightly changed with respect to the original version. Remaining known issues are being addressed as time allows.

The event display uses OpenGL behind the scenes. It works better on more recent implementations of OpenGL, and in 64bit. For this reason, the 64bit version is the default for the default software stacks available from /cvmfs.

List of changes with respect to the original version from 2001

The following changes have been applied to version 2.01:

Removed marker selection window as closing the window closes the whole application. The use case of markers is not documented, and nobody could remember how that was supposed to work, therefore it has been disabled.
Detector colors allow to set the amount of transparency. Note that tracks are still hidden.
Hardcopy EPS export is currently not supported. Instead, it is now possible to choose between different output formats:
- Color TGA
- Black and white TGA
- Color PNG (RGB), ignoring transparency
- Black and white PNG, ignoring transparency
- Color PNG (RGBA), including transparency
- Black and white PNG, including transparency
It is now also possible to drop the headers entirely.

Please read /cvmfs/delphi.cern.ch/README.DELGRA for the latest news.

DELGRA documentation

The original documentation for delgra can be found here.

Running DELGRA locally

The easiest way to run DELGRA is locally. This works if you have a Linux desktop running one of the supported operating systems. Install CVMFS, source the environment (. /cvmfs/delphi.cern.ch/setup.sh) and run:

    rungra

Running DELGRA with X11 forwarding on lxplus at CERN

The easiest way to run DELGRA remotely is by using X11 forwarding. This works if you are running a local X11 server. To connect to the node do

    ssh -Y lxplus.cern.ch
    rungra

As a DELPHI member, the environment will be automatically setup for you to use the software stack including DELGRA from cvmfs.

Running DELGRA over VNC with ssh tunneling

This procedure is a bit more complex though may have some advantages as you only need a vnc viewer locally. There is additional information available on a WIKI from LHCb, see here.

Known bugs and features

Bugs are tracked in CERN JIRA. Currently known issues include:

There is no postscript export. Simply print as TGA or PNG and convert the picture externally, if you need post script.
Issues have been seen on specific hardware where attempts to pick crash the event display when run locally. As a work around, do ssh -Y localhost from a shell and start it from there. This is a bit slower but stable.