From: John Stone (
Date: Wed Jan 22 2020 - 12:35:50 CST

  This sounds like some sort of OpenGL driver issue, or interference
caused by having window manager compositing enabled. Your renderer
appears to be an on-chip integrated Intel GPU. Historically there
have been quite a few problems with Intel integrated GPU graphics
drivers on Linux, and this may be another such example. Usually the
same chips work fine on Windows, which is why I blame the drivers.

If you can't get around the issue with Snapshot, then my recommendation
would be to use one of the ray tracing engines like TachyonInternal
instead. It won't render nearly as fast as OpenGL, but the image quality
will be higher and you won't be subject to driver bugs.

The other suggestion I have is to use a machine with a discrete GPU
rather than using the Intel integrated GPU, as the discrete GPU drivers
tend to be much higher quality, particularly on Linux.

  John Stone

On Wed, Jan 22, 2020 at 07:03:31PM +0100, Sebastian Reiter wrote:
> Hi,
> I am trying to make a movie of a protein with the ViewChangeRender
> and Movie Maker plugins and the snapshot render command.
> Particularly, I would like to slowly zoom into a specific site of a
> protein. However, snapshot sometimes seems to randomly zoom out a
> little from the current viewpoint. This causes the movie to stutter
> because the zooming motion is not continuous but interrupted by
> randomly offset frames.
> I know that it has something to do with snapshot, because a dry run
> with Movie Maker looks just fine. Also, the same thing happens, when
> I render a static scene with snapshot.
> Has anyone experienced this kind of issue before and knows a
> solution? If possible, I would like to stay with snapshot, because I
> am quite happy with the look and because more sophisticated
> rendering engines are too slow on my machine for a movie with a few
> hundred frames.
> I am using VMD 1.9.3 on a Ubuntu 18.04 64bit machine. The startup
> information of VMD says the following about the available graphics:
>     Info) Multithreading available, 4 CPUs detected.
>     Info)   CPU features: SSE2 AVX AVX2 FMA
>     Info) Free system memory: 3816MB (48%)
>     Info) No CUDA accelerator devices available.
>     Warning) Detected X11 'Composite' extension: if incorrect
> display occurs
>     Warning) try disabling this X server option.  Most OpenGL drivers
>     Warning) disable stereoscopic display when 'Composite' is enabled.
>     Info) OpenGL renderer: Mesa DRI Intel(R) HD Graphics 630 (Kaby
> Lake GT2)
>     Info)   Full GLSL rendering mode is available.
>     Info)   Textures: 2-D (16384x16384), 3-D (512x512x512),
> Multitexture (8)
> Thanks in advance and best regards
> Sebastian

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