[vtkusers] Combined on-screen and off-screen possible with VTK-7.0.0 on linux/X?
Michael Bachmann
Michael.Bachmann at synopsys.com
Mon Feb 8 04:52:46 EST 2016
Hello list!
Hello Sophonet!
First of all:
=> Thank you Sophonet for investigating this issue and for describing the patch to "VTKROOT/CMake/vtkOpenGL.cmake".
I applied your patch and it also re-enables offscreen rendering on a headless machine (were no X DISPLAY is available).
Actually I really wonder why there are only a few posts about this issue.
For the application I'm working on the ability of VTK7 to perform On-Screen and Off-Screen rendering with a single build of VTK is an absolute must-have! (Just like it was in VTK5 and VTK6)
Please take the suggestion of Sophonet into account and re-enable it at least for the OpenGL rendering backend.
Making this available for the OpenGL2 backend should also be considered.
Building the software twice, e.g. like it is done for paraview (non-headless) and the paraview server (headless) is not an option for everyone.
Actually is quite a big burden which has been silently put on the shoulders of VTK users.
So please: Provide the facilities to perform On-Screen and Off-Screen rendering with a single build of VTK using OSMesa and X on Linux again!
Best regards,
Michael
Date: Thu, 21 Jan 2016 14:54:46 +0100
From: Sophonet <vtk12af6bc42 at kant.sophonet.de>
To: vtkusers at vtk.org
Subject: Re: [vtkusers] Combined on-screen and off-screen possible
with VTK-7.0.0 on linux/X?
Message-ID: <ac1f14a73f567e2e8e5916a5c942dc04 at srv19.sysproserver.de>
Content-Type: text/plain; charset=UTF-8; format=flowed
As one further follow-up of my two earlier e-mails, I have partly answered the question myself... remember, my question is related to the OpenGL (not OpenGL2) rendering backend.
Two observations:
1. It seems that the current CMake flag VTK_OPENGL_HAS_OSMESA is useless, since it does not set anything relevant (see my e-mail below) 2. It seems that combined on-screen / off-screen rendering is possible (on Mesa 9.2.3 using the OpenGL rendering backend):
As a quick hack, I have changed VTKROOT/CMake/vtkOpenGL.cmake such that
* VTK_USE_OSMESA = True (triggers find_package OSMesa)
* VTK_USE_X = True (triggers find_package OpenGL)
...and (at the bottom) vtk_module_link_libraries links to *both*, ${OSMESA_LIBRARY} and ${OPENGL_LIBRARIES}.
After this hack, I can successfully launch interactive (glx-)renderwindows as well as set (occasionally) set SetOffscreenRenderingOn().
Therefore, my suggestion would be to
- remove VTK_OPENGL_HAS_OSMESA
- change the vtkOpenGL.cmake such that VTK_USE_OSMESA is exposed as an advanced option and is not exclusive w.r.t. VTK_USE_X, but may be set at the same time.
Any comments?
Thanks,
Sophonet
Am 2016-01-19 11:06, schrieb Sophonet:
> As a follow-up, I have done some more investigations myself and am
> still lost:
>
> According to http://www.vtk.org/Wiki/VTK/OSMesa_Support, it seems that
> the legacy OSMesa library on linux systems is not needed anymore, but
> that software renderers (such as gallium llvm) can provide off-screen
> rendering themselves. Correct?
>
> When looking at VTKROOT/CMake/vtkOpenGL.cmake, it appears (not
> perfectly sure though) that in this case VTK_OPENGL_HAS_OSMESA needs
> to be turned on, since this flag sets VTK_CAN_DO_OFFSCREEN to 1.
> However, it seems to me that VTK_CAN_DO_OFFSCREEN is not used anywhere
> else (did a thorough "grep" on that keyword in the source tree).
>
> It seems that Marcus (Hanwell) was responsible for many of these
> changes in CMake - Marcus, can you help?
>
> What I would like to do is (see my first e-mail below) to
> simultaneously use interactive rendering and (occasionally) off-screen
> rendering (for generating static images), which was possible on Linux
> in earlier versions of VTK (e.g. 5.10), but is not possible anymore.
>
> Thanks,
>
> Sophonet
>
>
> Am 2016-01-15 12:44, schrieb Sophonet:
>> Dear list,
>>
>> in my application, I would like to display a vtkRenderWindow for user
>> interaction, but I also would like to use off-screen functionality
>> simultaneously to render pre-defined views / snapshots that are shown
>> as static images, like "thumbnails" for different datasets.
>>
>> This was possible in VTK 5.10 on linux (by creating a dedicated
>> vtkRenderWindow per thumbnail, setting OffScreenRenderingOn,
>> rendering and capturing the resulting image with a vtkWindowToImageFilter).
>>
>> In VTK-7.0.0.rc1, using the OpenGL rendering backend on Mesa 9.2.3, I
>> now get a segfault with the following backtrace:
>>
>> (gdb) bt
>> #0 0x00007fffd045db90 in xcb_glx_get_string_string_length ()
>> from /usr/lib64/libxcb-glx.so.0
>> #1 0x00007fffd0cce605 in ?? () from /usr/lib64/libGL.so.1
>> #2 0x00007fffd0ccc2b6 in ?? () from /usr/lib64/libGL.so.1
>> #3 0x00007fffd14cd086 in
>> vtkOpenGLExtensionManager::ReadOpenGLExtensions() ()
>> from
>> /import/QUINTA/non-public/software/linux-install/quinta_gcc_debug/lib
>> /libvtkRenderingOpenGL-7.0.so.1
>> #4 0x00007fffd14cbd50 in vtkOpenGLExtensionManager::Update() ()
>> from
>> /import/QUINTA/non-public/software/linux-install/quinta_gcc_debug/lib
>> /libvtkRenderingOpenGL-7.0.so.1
>> #5 0x00007fffd14cafd7 in
>> vtkOpenGLExtensionManager::ExtensionSupported(char const*) ()
>> from
>> /import/QUINTA/non-public/software/linux-install/quinta_gcc_debug/lib
>> /libvtkRenderingOpenGL-7.0.so.1
>> #6 0x00007fffd14ec8ea in vtkOpenGLRenderWindow::OpenGLInitContext()
>> ()
>> from
>> /import/QUINTA/non-public/software/linux-install/quinta_gcc_debug/lib
>> /libvtkRenderingOpenGL-7.0.so.1
>> #7 0x00007fffd14eae6d in vtkOpenGLRenderWindow::OpenGLInit() ()
>> from
>> /import/QUINTA/non-public/software/linux-install/quinta_gcc_debug/lib
>> /libvtkRenderingOpenGL-7.0.so.1
>> #8 0x00007fffd1576932 in
>> vtkXOpenGLRenderWindow::CreateOffScreenWindow(int, int) ()
>>
>> Besides a remark that probably there could be better error handling
>> than just letting the app crash without an exception being thrown, I
>> would like to know if joint on-screen rendering and off-screen
>> rendering is still possible somehow with VTK-7.0.0.
>>
>> I have made two approaches when configuring via CMake: (i) Setting
>> VTK_OPENGL_HAS_OSMESA=True (no effect, I think I remember that in
>> earlier versions, this allowed OSMESA_INCLUDE_DIR etc. to be set;
>> this is not the case anymore, so does this flag still do something?
>> Note that for VTK 5.10 as mentioned above I did not have to set this
>> explicitly), (ii) Setting USE_OFFSXCREEN_EGL=True - resulting in an
>> error that this could not be combined with VTK_USE_X.
>>
>> On Windows, combining on-screen and off-screen rendering as described
>> in the second paragraph is possible.
>>
>> Any suggestions would be welcome, the Wiki page I have found on this
>> topic is not fully understandable to me
>> (http://www.vtk.org/Wiki/VTK/OSMesa_Support; does this mean that I
>> have to switch on VTK_OPENGL_HAS_OSMESA or not?...)
>>
>> Thanks,
>>
>> sophonet
>>
>>
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