I don't know if this will help at all... but, here goes:<br><br>In your original email you said you have VTK_USE_OFFSCREEN on but VTK_USE_DISPLAY off.<br><br>VTK_USE_OFFSCREEN is simply used to control the *default* value of vtkRenderWindow's OffScreenRendering property. VTK_USE_DISPLAY controls what VTK tests are run: tests that require the display (whether offscreen rendered or not) are skipped if VTK_USE_DISPLAY is off.
<br><br>So, it probably makes no difference to your particular case, here, but in my mind, it doesn't make a lot of sense to set VTK_USE_OFFSCREEN to ON unlesss VTK_USE_DISPLAY is also ON. "OffScreen" rendering occurs invisibly, but it still requires use of the display...
<br><br>Now this is all strictly from the VTK side of the fence. Don't know if these settings propagate to any other logical implications on the ParaView side of the fence.<br><br><br>HTH,<br>David<br><br><br><div><span class="gmail_quote">
On 11/17/06, <b class="gmail_sendername">John Biddiscombe</b> <<a href="mailto:biddisco@cscs.ch">biddisco@cscs.ch</a>> wrote:</span><blockquote class="gmail_quote" style="border-left: 1px solid rgb(204, 204, 204); margin: 0pt 0pt 0pt 0.8ex; padding-left: 1ex;">
Francois<br><br>vtk is compiled with OSMesa, I was using a cvs version around the end<br>octobers - I just did a cvs update and clean build and the same problem<br>exists. However, I believe I had problems /before /26 oct. I originally
<br>attributed my trouble to using pvserver from pv3 and pvclient from pv2,<br>but I'm not doing that any more - it was working in early oct, but I<br>don't know exactly when I broke it.<br><br>I tried various DISPLAY localhost:
0.0 and :0 combinations, with and<br>without xservers available, but always the same trouble.<br><br>(The machines are headless, so offscreen rendering must be software)<br><br>Anything else I can try?<br><br>JB<br>> Hi,
<br>><br>> Assuming you use cvs version of ParaView, there was some change related to offscreen rendering in VTK on October 26. Is it when the warnings started to occur?<br>><br>> Under X11, if vtk was compiled with OSMESA (OS=OffScreen) it creates an OSMesa window and an OSMesa context.
<br>> Otherwise, (NEW) it tries to use a hardware accelerated offscreen rendering by creating a window and an OpenGL context and asking for OpenGL extensions GL_EXT_framebuffer_object and GL_ARB_texture_non_power_of_two.
<br>> It those extensions are not available, the OpenGL context and window are destroyed and it tries to use a Pbuffer offscreen. If not available, it uses a GLX Pixmap.<br>><br>> Under Win32, it first tries the hardware accelerated offscreen rendering (NEW). If the extensions are not available, an Offscreen Device Context is used.
<br>><br>> The source code is in VTK/Rendering: vtkXOpenGLRenderWindow, vtkWin32OpenGLRenderWindow and the superclass vtkOpenGLRenderWindow.<br>><br>> Kent Eschenberg wrote:<br>><br>>> No fixes here - just some related info.
<br>>><br>>> --On 11/16/2006 02:55:05 PM +0100 <a href="mailto:biddisco@cscs.ch">biddisco@cscs.ch</a> wrote:<br>>><br>>>> I keep getting a warning that one or more of the servers cannot access<br>
>>> a display and so compositing will be disabled.<br>>>><br>>> ...<br>>><br>>>> It used to work ok, but I must have broken something. Anyone got any idea?<br>>>><br>>> 1) Another possible cause is that something changed in your OS' defaults. Upgrades to some of our systems sometimes replaces various graphics header files.
<br>>><br>>> 2) You might try changing<br>>><br>>><br>>>> and set environment to (also tried blank for DISPLAY)<br>>>> DISPLAY :0<br>>>><br>>> to instead set DISPLAY to localhost:
0.0.<br>>><br>>> 3) Using X Windows and using OpenGL are two different issues; linking t Mesa does not always eliminate the need to access X.<br>>><br>>> For example, the code may ask X for a font definition that it uses to prepare the equivalent font in Mesa.
<br>>><br>>> There is also a bug (may not be on the formal list) where pvbatch (and maybe pvserver) still need to see an X server though they don't really use it.<br>>><br>>> 4) Finally, keep in mind that there are 2 different types of "off screen rendering".
<br>>><br>>> The one that is officially known by that name has been in OpenGL from the beginning (see glXCreateGLXPixmap). It writes to an X pixmap instead of the screen (I suspect there is also a Windows version). I *think* this approach still uses the graphics card
<br>>> for acceleration.<br>>><br>>> In addition, Mesa can render off screen, into a buffer, and does not need a graphics card or an X pixmap - it tries to hide all that from the application.<br>>>
<br>>> Of course, all this is just a list of options; perhaps someone who knows the internals can comment on how VTK/ParaView actually does things???<br>>><br>>> Kent<br>>> Pittsburgh Supercomputing Center
<br>>><br>><br>><br>><br><br><br>--<br>John Biddiscombe, email:biddisco @ cscs.ch<br><a href="http://www.cscs.ch/about/BJohn.php">http://www.cscs.ch/about/BJohn.php</a><br>CSCS, Swiss National Supercomputing Centre | Tel: +41 (91)
610.82.07<br>Via Cantonale, 6928 Manno, Switzerland | Fax: +41 (91) 610.82.82<br><br>_______________________________________________<br>ParaView mailing list<br><a href="mailto:ParaView@paraview.org">ParaView@paraview.org
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