[vtkusers] Qt5/VTK application does not start correctly (with X11 forwarding)

[David Gobbi]

The "-X" vs "-Y" doesn't mean encrypted vs. non-encrypted.  See the ssh man
page here:

https://man.openbsd.org/ssh

Specifically:   -Y    Enables trusted X11 forwarding.

The "-Y" gives the client access to the GPU, and is necessary for all but
the most basic rendering.  I'm not sure if putty provides this option,
since I do nearly all of my work on Linux or Mac.

 - David



On Fri, Aug 11, 2017 at 7:52 AM, Sophonet <vtk12af6bc42 at kant.sophonet.de>
wrote:

> Yes, well, I am using a Windows machine and putty. Putty has an option in
> it's configuration dialog. I don't know whether the X connection is
> encrypted (-X) or not (-Y).
>
>
>
> On 2017-08-11 14:31, David Gobbi wrote:
>
>> How are you doing the X11 forwarding?  Are you using "ssh -Y"?
>>
>> On Fri, Aug 11, 2017 at 6:20 AM, Sophonet
>> <vtk12af6bc42 at kant.sophonet.de> wrote:
>>
>> Hi list,
>>>
>>> an application using VTK 8.0.0 and Qt 5.9.1 (built with -opengl
>>> desktop) does not start correctly (using X11 forwarding). After
>>> displaying an error message "failed to get the current screen
>>> resources", there is another error message
>>>
>>> vtkXOpenGLRenderWindow (0x55f891d77a80): GL version 2.1 with the
>>> gpu_shader4 extension is not supported by your graphics driver but
>>> is required for the new OpenGL rendering backend. Please update your
>>> OpenGL driver. If you are using Mesa please make sure you have
>>> version 10.6.5 or later and make sure your driver in Mesa supports
>>> OpenGL 3.2.
>>>
>>> However, my Ubuntu 17.04 system has Mesa 17.0.7, glxgears works fine
>>> (using X11 forwarding) and glxinfo shows (among other things) the
>>> correct driver - see below, so I am a bit puzzled what is going on.
>>> Any hints?
>>>
>>> Thanks,
>>>
>>> sophonet
>>>
>>> P.S.: The first call in my application's main() function is
>>> QSurfaceFormat::setDefaultFormat, see below. The same application
>>> runs fine and without problems on Windows.
>>>
>>> #if QT_VERSION >= 0x050500
>>> // before initializing QApplication, set the default surface
>>> format, see documentation
>>>
>>> QSurfaceFormat::setDefaultFormat(QVTKOpenGLWidget::defaultFormat());
>>> #endif
>>>
>>> GLX version: 1.2
>>> GLX extensions:
>>> GLX_ARB_get_proc_address, GLX_ARB_multisample,
>>> GLX_EXT_import_context,
>>> GLX_EXT_visual_info, GLX_EXT_visual_rating,
>>> GLX_MESA_multithread_makecurrent, GLX_MESA_query_renderer,
>>> GLX_OML_swap_method, GLX_SGIS_multisample, GLX_SGIX_fbconfig,
>>> GLX_SGI_make_current_read
>>> Extended renderer info (GLX_MESA_query_renderer):
>>> Vendor: VMware, Inc. (0xffffffff)
>>> Device: llvmpipe (LLVM 4.0, 128 bits) (0xffffffff)
>>> Version: 17.0.7
>>> Accelerated: no
>>> Video memory: 3949MB
>>> Unified memory: no
>>> Preferred profile: core (0x1)
>>> Max core profile version: 3.3
>>> Max compat profile version: 3.0
>>> Max GLES1 profile version: 1.1
>>> Max GLES[23] profile version: 3.0
>>> OpenGL vendor string: VMware, Inc.
>>> OpenGL renderer string: Gallium 0.4 on llvmpipe (LLVM 4.0, 128 bits)
>>> OpenGL version string: 3.0 Mesa 17.0.7
>>> OpenGL shading language version string: 1.30
>>>
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