This G4 Graphics Driver creates a HepRep File suitable for viewing
by the HepRApp, Wired4 or FRED Event Display clients.
It requires no external packages.

The HepRep graphics format is further described at
http://www.slac.stanford.edu/~perl/heprep/


Two different drivers are available for either HepRep1 or HepRep2.


Driver: HepRepFile
------------------
The version of HepRep produced by this driver is HepRep Version 1.

Writes files with file extension .heprep.

First file is written to current directory and is named G4Data0.heprep.
Subsequent files increment the number, as in G4Data1.heprep, G4Data2.heprep...

To specify a different output file directory (instead of current directory),
set G4HEPREPFILE_DIR

To specify a different output file name (instead of G4Data),
set G4HEPREPFILE_NAME

To repeatedly overwrite the same output file (instead of having incremental
numbers at the end of the file name),
set G4HEPREPFILE_OVERWRITE

By default, invisible objects are not culled but are left in the heprep file
with their visibility initially set to false (so that you can subsequently
choose to make them visible from within the heprep browser).
To force culling of invisible objects,
set G44HEPREPFILE_CULL

View the file using the HepRApp HepRep Browser, available from:
http://www.slac.stanford.edu/~perl/HepRApp

HepRApp can read xml files in zipped format as well as unzipped,
so you can save space by applying gzip to the xml file.
This will reduce the file to about five percent of its original size.

Joseph Perl
15 November 2007


Driver: HepRepXML
-----------------
The version of HepRep produced by this driver is HepRep Version 2.

This driver can write both Binary HepRep (.bheprep) and XML HepRep 
(.heprep) files. Binary HepRep files are a one-to-one translation
of XML HepRep files, but they are considerably shorter and faster
to parse by a HepRepViewer such as WIRED 4.

You can view the files using the WIRED 4 Event Display, available from:

http://wired4.freehep.org

Both Binary HepRep and XML HepRep can be compressed using the standard
zlib library if linked into Geant4 using G4LIB_USE_ZLIB. If a standard
zlib is not available (WIN32-VC for instance) you should also set 
G4LIB_BUILD_ZLIB to build G4zlib included with Geant4.

HepRep files (Binary and XML) can contain multiple HepRep events/geometries.
If the file contains more than one HepRep it is not strictly XML anymore.
Files can be written in .heprep.zip, .heprep.gz or .heprep format and their
binary versions .bheprep.zip, .bheprep.gz or .bheprep.

The .heprep.zip is the default for file output, the .heprep is the default 
for stdout and stderr.

(Optional) To set the filename with a particular extension such as: 
.heprep.zip, .heprep.gz, .heprep, .bheprep.zip, .bheprep.gz or .bheprep
use for instance:

/vis/scene/create filename.bheprep.zip


(Optional) To create separate files for each event, you can set a suffix such as 
"-0001" to start writing files from filename-0001.bheprep.zip to 
filename-9999.bheprep.zip (or up), while "-55-sub" will start write files 
filename-55-sub.bheprep.zip to filename-99-sub.bheprep.zip (or up).

/vis/heprep/setEventNumberSuffix -0001
(Note: suffix has to contain at least one digit)


(Optional) To route the HepRep XML output to stdout (or stderr), 
by default uncompressed, use:

/vis/scene/create stdout


To select the driver, where the file if not create by scene is set to 
G4HepRepOutput.heprep.zip, use:

/vis/open HepRepXML


(Optional) To write a geometry, use:

/vis/viewer/flush


(Optional) To signal a change in geometry (to be written with the next event), use:

/vis/viewer/refresh


To write 10 events (and geometries), use:

/run/beamOn 10


(Optional) To accumulate multiple (5) G4 events into one HepRep event, use:
/vis/scene/endOfEventAction accumulate
/run/beamOn 5
/vis/viewer/update


(Optional) To add attributes to each point on a trajectory, use:
/vis/heprep/addPointAttributes 1
Be aware that this may increase the size of the output dramatically.


(Optional) You may use the commands:
/vis/viewer/zoom                            to set an initial zoom factor
/vis/viewer/set/viewpointThetaPhi           to set an initial view point
/vis/heprep/setCoordinateSystem uvw         to change the coordinate system, where uvw can be "xyz", "zxy", ...


(Optional) You may decide to write .zip files with events and geometry separated (but linked).
This results in a smaller zip file, as the geometry is only written once. Use the command:

/vis/heprep/appendGeometry false


(Optional) To close the file, remove the SceneHandler, use:

/vis/sceneHandler/remove scene-handler-0


Limitations:

Only one SceneHandler can exist at any time, connected to a single Viewer. 
Since the HepRep format is a model rather than a view this is not a real
limitation. In WIRED 4 you can create as many views (SceneHandlers) as you like.

1 June 2005
Mark.Donszelmann@slac.stanford.edu