[vtkusers] Re: Offscreen Rendering

[John Shalf]

Miguel Angel Martin Fernandez wrote:
> 
> Hello vtkusers!
> 
> The script "run.sh" does work if i am actually running the program via
> telnet, as long as i have 'XOpenDisplay((char *)NULL)' in my
> vtkOpenGLOffscreenRenderWindow, that way XOpenDisplay defaults to the
> value of the DISPLAY environment variable (--> i read the man page!! )

The default value of the DISPLAY variable may well be the
host that executes the program.  So that would mean all of
the rendering would be redirected to the host you'd
telnetted from in the worst case.  Overriding with ":0"
ensures that it is rendering on the local host (could be
more specifically "localhost:0.0").  

> However what i am actually trying to do is parallel rendering on a
> linux cluster with mpi, so programs are called via rsh, and with this
> approach the script doesn't seem to work. However it did work by telling
> XOpenDisplay exactly what display i wanted:
> 
>                   'XOpenDisplay("<name_of_R>:0.0")'

Is <name_of_R> the name of the machine that the local MPI
process is executing on, or is it the name of the host that
started the MPI job?  Some X implementations want
"localhost:0.0" or "$hostname:0.0", but the ":0" is usually
enough.  Seems your machine is one of the former...

-john