[vtkusers] Offscreen Rendering & Linux

Tue Oct 19 08:08:42 EDT 2010

Hi Mark,

I'm jumping into this conversation a little late, so I might have
missed a couple things.  But it seems that you are going to need to
connect to an X server of some sort, so you should try using a hidden
X server, rather than just a hidden window.

Since I have only one monitor on my computer, but have a dual-head
video card, I use my second head (with no monitor attached) for
running VTK dashboard tests or other graphics-related things that I
don't want to see on-screen.  It seems to me that you could do
something similar, and when you log-in remotely you could set your
DISPLAY variable to use a hidden, hardware-accelerated X server.

  David

On Tue, Oct 19, 2010 at 5:39 AM, endlosschleife1
<endlosschleife1 at googlemail.com> wrote:
> Hi Lars,
>
> sorry for the late reply. Thanks a lot! I just tried this out. It does seem
> to not open the X Window, but I still need a X connection, otherwise my code
> terminates when it calls the GetDesiredVisualInfo() method. For my purposes
> I would need a VTK based rendering service that I can interact with remotely
> (starting it from a SSH terminal, sending rendered data to a client through
> a socket etc.). I will look into this some more. I wonder if I can hardcode
> all the information that the render window needs and tries to retrieve from
> the display.
>
> Thanks again!
>
> Mark
>
>
> 2010/10/3 Lars Friedrich Lars <lars-friedrich at gmx.net>
>>
>> Hello Mark,
>>
>>
>> I'm having a comparable problem. I found a solution that works for me,
>> maybe this is also a solution to your situation ...
>>
>> Basically, I want to hide the X-window when using GL hardware off-screen
>> rendering. My first experiments involved XUnmapWindow - however, as the X
>> window is initially mapped in the CreateAWindow()-method, the window will
>> appear at least for a few milliseconds prior to calling XUnmapWindow(). This
>> is neither "nice", nor a solution to your problem.
>>
>> Therefore, I inherited from vtkXOpenGLRenderWindow and overrode the
>> CreateAWindow()-method. I simply eliminated the code block that calls
>> XMapWindow() initially -> the off-screen window never gets mapped ...
>>
>> The inherited class is however suboptimal, as I had to redefine the
>> vtkXOpenGLRenderWindowInternal class (forward declaration ...).
>>
>> I attachted a simple example (hidex.cxx) that makes use of the simple
>> inherited class. If you want, try it, and please let me know whether or not
>> it works for you.
>>
>>
>> regards,
>>
>> lars
>>
>>
>>
>>
>> -------- Original-Nachricht --------
>> > Datum: Thu, 23 Sep 2010 10:54:54 -0400
>> > Von: Aashish Chaudhary <aashish.chaudhary at kitware.com>
>> > An: endlosschleife1 <endlosschleife1 at googlemail.com>
>> > CC: vtkusers at vtk.org
>> > Betreff: Re: [vtkusers] Offscreen Rendering & Linux
>>
>> > Mark,
>> >
>> > I believe that as of now if you want to use OpenGL driver and not Mesa
>> > it
>> > requires opening an windows or else you have to use Mesa (like you did).
>> > There is no workaround for the former case.
>> >
>> > On Thu, Sep 23, 2010 at 6:48 AM, endlosschleife1 <
>> > endlosschleife1 at googlemail.com> wrote:
>> >
>> > > Hello,
>> > >
>> > > has anybody some experience with doing offscreen rendering under Linux
>> > with
>> > > graphics acceleration support and give me some hints on how to get
>> > > this
>> > to
>> > > work?
>> > >
>> > > I'm using a vtkOpenGLRenderWindow and set OffScreenRendering to on.
>> > > With
>> > > that it does really not render into a window, but VTK still opens an X
>> > > Window (apparently it needs its handle). So for instance when I try to
>> > start
>> > > a VTK based app remotely via SSH I get the following error message:
>> > >
>> > > # An unexpected error has been detected by Java Runtime Environment:
>> > > #
>> > > #  SIGSEGV (0xb) at pc=0xb2b5b4f5, pid=16472, tid=3044047776
>> > > #
>> > > # Java VM: Java HotSpot(TM) Client VM (1.6.0-b105 mixed mode, sharing)
>> > > # Problematic frame:
>> > > # C  [libvtkRenderingJava.so.5.6.0+0x66c4f5]
>> > > _ZN22vtkXOpenGLRenderWindow13CreateAWindowEv+0x37b
>> > > #
>> > > # An error report file with more information is saved as
>> > > hs_err_pid16472.log
>> > > #
>> > > # If you would like to submit a bug report, please visit:
>> > > #   http://java.sun.com/webapps/bugreport/crash.jsp
>> > > #
>> > >
>> > > Is there any way around the need for VTK to open an X window?
>> > > Basically
>> > I
>> > > would like to know if that problem is even fixable or if I need to
>> > > look
>> > for
>> > > other workarounds.
>> > >
>> > > When I build VTK with MESA enabled it works, but the performance
>> > > without
>> > > accelaration is unacceptable.
>> > >
>> > > Thanks,
>> > > Mark
>> > > _______________________________________________
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>> > >
>> >
>> >
>> > --
>> > | Aashish Chaudhary
>> > | R&D Engineer
>> > | Kitware Inc.
>> > | www.kitware.com
>>
>> --
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>> Jetzt freischalten! http://portal.gmx.net/de/go/maxdome
>
>
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