== Graphical Login (VNC)
[[PageOutline]]

[[span(style=color: #FF0000, '''Graphical Login (VNC) only with JURECA login possible.''')]]


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Remote visualization, either implemented within visualization applications themselves or through server software, \\ eliminates the need for off-site file transfers and allows HPC users to run a broad range of visualization tools \\
in-place on the supercomputer where the data resides and more compute resources are available.

A graphical login using Virtual Network Computing (VNC) simplifies the access to remote visualization. \\
A broad variety of Linux applications with graphical user interface and/or need for OpenGL can be used directly on the supercomputers via VNC.
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VNC provides a complete graphical and remote desktop by \\
* transmitting the keyboard and mouse events from your computer to the remote machine and \\
* relaying the graphical screen updates back in the other direction.

VNC is
* platform-independent (VNC viewers are available for almost any operating system)
* application-independent (no need for remote visualization support inside the application)
* multiple clients may connect to a VNC server at the same time sharing the same session (support, presentation, group discussions)

[wiki:vnc3d/details ... more details]

\\
=== Ok, what do I have to do?

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'''Strudel''' (Scientific Remote Desktop Launcher)
  * cross-platform application for Linux, MacOS and Windows
  * Strudel '''should be used''' to access remote graphical desktop on JURECA
  * developed
    * by the Multi-modal Australien ScienceS Imaging and Visualization Environment ([https://www.massive.org.au MASSIVE]) team 
    * under the NeCTAR-funded [https://www.massive.org.au/cvl Characterisation Virtual Laboratory]
...................................................................................................................................................................................\\
'''[wiki:vnc3d/strudel ==> Download & Install Instructions <==]'''
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\\

alternative option)
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'''[wiki:vnc3d/manual vncserver/ssh/vncviewer]''' (manual connection)
  * manual start of VNC server on JURECA
  * manual tunnel for VNC data
  * manual start of VNC viewer on local machine
...................................................................................................................................................................................\\
'''[wiki:vnc3d/manual ==> Install instructions <==]'''
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==== IMPORTANT: Use hardware acceleration in your VNC session 

'''vglrun''':\\
Any OpenGL application running in your VNC session should be started with '''vglrun''' to use the hardware acceleration provided by the visualization nodes.

==== e.g. ParaView
Open a terminal in your VNC session and:
{{{ #!sh
# What versions of ParaView are available?
module spider ParaView

# load ParaView dependency
module load intel-para

# load ParaView
module load ParaView
}}}

{{{ #!sh
# start ParaView Server and GUI using VirtualGL for hardware acceleration
srun -n 24 vglrun pvserver
vglrun ParaView
}}}
Connect to the pvservers on localhost:11111

==== e.g. !VisIt
Open a terminal in your VNC session and:
{{{ #!sh
# change Stage
module use /usr/local/software/jureca/OtherStages
module load Stages/.Stage1

# What versions of VisIt are available?
module spider VisIt

# load VisIt dependency
module load intel-para/2015.07

# load VisIt
module load VisIt/2.10.0
}}}

{{{ #!sh
# start VisIt using VirtualGL for hardware acceleration
vglrun visit -hw-accel
}}}


== Hints

* press F8 to enter VNC-Viewer Options (example: toggle to full screen)

* sync clipboard between client and server
{{{ #!ShellExample
    vncconfig -poll=100
}}}

* To reset your VNC-password delete ~/.vnc/passwd

----
any feedback welcomed - [mailto:h.zilken@fz.juelich.de], [mailto:j.goebbert@fz-juelich.de]