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Environment Variables
Several environment variables are used by VMD to determine the
location of certain files and directories. These variables are
accessible to text interface through array env.
These variables include:
- DISPLAY :
(Unix-only)
The X-Windows display that VMD should use for displaying the
VMD windows and menus, as well as the graphics window. If this
environment variable is not overridden by VMDGDISPLAY all
VMD windows will be directed to this display.
- VMDDIR :
The directory which contains the VMD data files (such as this help
file) and architecture-specific executables. By default, this is
/usr/local/lib/vmd on Unix systems, and
C:\Program Files\University of Illinois\VMD
on Windows sytems.
- VMDTMPDIR :
The directory which VMD should use for temporary data files. By
default, this is /tmp, or /usr/tmp on Unix systems, and
C:\
on Windows.
- VMDCUSTOMIZESTARTUP :
(Unix-only)
The name of a C-shell script to source prior to running the actual
VMD process. This shell script can contain any commands necessary for
performing machine-specific spaceball, graphics, and other customizations
necessary to run VMD. This can be anything from a simple script that
sets the right serial port for a Spaceball based on the hostname, or
it can be a complex script for turning on a projection system, logging
demos, configuring multi-display stereo-framelock features, etc.
- VMDBABELBIN :
The complete path and filename for the program babel, which is used
by VMD to convert molecular structure/coordinates files into PDB
files which VMD can actually understand. If this is not set
explicitly, the VMD startup script will attempt to find babel in
the current path. If Babel cannot be found or is not installed, VMD will not be able to read molecular file formats other than PDB,
PSF, and binary DCD files.
- VMDFILECHOOSER :
Specifies which file chooser to use for loading and saving files from the
GUI. At present, this should be either FLTK, which uses Fltk's platform-
independent file chooser, or TK, which uses Tk's file chooser. The Tk
file chooser is the default and uses a native Windows interface on Windows
platforms. The Fltk file chooser looks the same on all platforms, supports
tab completion but not drive letters, and is probably most appropriate for
Unix environments. The file chooser can be overridden at any time by
changing the environment variable (e.g., in Tcl, set env(VMDFILECHOOSER) FLTK).
- VMDFORCECPUCOUNT :
Specifies the maximum number of CPUs or CPU cores that VMD should
use when running on a multiprocessor or multicore computer system.
By default, VMD will use all of the processors on the host machine.
This option can be used to prevent VMD from ``hogging'' CPUs or to
make it abide by job submission policies required on large
supercomputer systems, when running batch mode.
- VMDCAVEMEM :
(Unix-only)
This overrides the default size of the shared memory arena
which is allocated by VMD when the CAVE starts up. The variable
must be an integer number of megabytes. Since this is the only
shared memory pool allocated, and it is done only once, you must
choose a value sufficient to account for the largest scene you
intend to render in VMD in that CAVE session. The default value
unless otherwise specified is 80 Megabytes. Values of 200MB to 512MB
are commonly needed for large molecular systems containing several
hundred thousand atoms.
- VMDFREEVRMEM :
(Unix-only)
This overrides the default size of the shared memory arena
which is allocated by VMD when the FreeVR starts up. The variable
must be an integer number of megabytes. Since this is the only
shared memory pool allocated, and it is done only once, you must
choose a value sufficient to account for the largest scene you
intend to render in VMD in that FreeVR session. The default value
unless otherwise specified is 80 Megabytes. Values of 200MB to 512MB
are commonly needed for large molecular systems containing several
hundred thousand atoms.
- VMDFORCECONSOLETTY :
(Unix-only, intended only for clusters
This environment variable forces VMD to treat the text console
as an interactive terminal, despite what the operating system says.
This is only useful for running an interactive VMD session on a
Clustermatic or Scyld Linux cluster node.
- VMDGDISPLAY :
(Unix-only)
The name of an X-Windows display that VMD will use to display
the graphics window. This environment variable is only used
on Unix systems. Through the use of the the DISPLAY and
VMDGDISPLAY envrironment variables, the VMD graphics window can
be placed on a separate screen from the windows and menus. This is
particularly useful when giving 3-D demonstrations using a projector.
The windows and menus can be kept on a different screen from the graphics
so that they do not distract the audience.
- VMDGLSLVERBOSE :
OpenGL Shading language compiler diagnostic errors only printed
only when this environment variable is set.
- VMDHTMLVIEWER :
The name of a command that will run a web browser in the background
(Netscape, Mozilla, Firefox or whatever you prefer)
that VMD should use to display HTML documents (such as this help
file). By default, on UNIX, this is mozilla. (usage examples in Tcl:
set env(VMDHTMLVIEWER) ``mozilla -remote openURL(%s)",
set env(VMDHTMLVIEWER) ``mozilla %s SPMamp;")
- VMDIMAGEVIEWER :
The name of the external program to use for displaying VMD snapshots (or other images), in various formats.
- VMDIMMERSADESKFLIP :
Enable a special reversed/reflected stereo projection mode for
use with experimental displays based on LCD panels, phase plates,
and beam splitters.
- VMDMACENABLEEEXTENSIONS :
Enable performance-oriented OpenGL rendering extensions
which are disabled by default. These extensions have been
observed to trigger instability on some MacOS X systems.
- VMDMAXAASAMPLES :
Override the maximum requested OpenGL multisample antialiasing
sample depth with a user-specified value. The VMD default is
normally 8 samples per pixel. Some video cards exhibit poor
performance with large numbers of antialiasing samples and must
be restricted to 5 or fewer samples per pixel.
- VMDMSECDELAYHACK :
Add in a user-specified delay which causes VMD to sleep for
specified number of milliseconds each time it renders the molecular
scene on the display. This feature is meant as a workaround to
poor performing display drivers which make the windowing system
unresponsive if VMD is allowed to run unrestricted at maximum drawing rate.
- VMDMSMSUSEFILE :
Force VMD to communicate with MSMS through the filesystem rather
than with the socket-based network interface. This option can be
used when the socket interface isn't working properly for some reason.
This is the default behavior when using VMD on Windows.
- VMDNOCUDA :
Force VMD not to use CUDA-based GPU acceleration, even if CUDA
support was compiled in, and CUDA-capable devices are detected at startup.
This can be used in cases where a GPU or GPU drivers prove to be unreliable
for computation, for benchmarking vs. CPU-only implementations, and
to prevent VMD from using a GPU that's already oversubscribed by other
processes running on the same machine.
- VMDCUDADEVICEMASK
This environment variable limits VMD to running
GPU-accelerated algorithms on a specific subset
of GPUs, based on a hexadecimal mask. For example, to
allow rendering on only the first two GPUs, one would
set the mask to 0x3; to use only the second GPU, the mask
would be set to 0x2.
- VMDDISABLESTEREO :
(Unix)
Prevents VMD from enabling stereoscopic display features. This is
normally only used as a workaround for buggy display drivers.
- VMDPREFERSTEREO :
(Unix, MacOS X)
On Unix systems using X11, this environment variable allows NVidia Quadro
users to override the normal X11 visual search order, skipping multisample
capable visuals in favor of stereo visuals. VMD still attempts to get the
more complex visuals first, but if it comes down to a choice between stereo
and multisample as mutually exclusive options, this variable provides
the ability to force the use of stereo if available.
On MacOS X, this environment variable tells VMD to create a
a stereo-capable display window, even at the risk of terminating the
program if the request is denied.
- VMDSCRDIST :
Distance to the VMD image plane.
- VMDSCRHEIGHT :
Height of the VMD image plane.
- VMDSCRPOS :
Position of the VMD graphics window (x,y).
- VMDSCRSIZE :
Size of the VMD graphics window (x,y).
- VMD_EXCL_GL_EXTENSIONS :
Disable the use of named OpenGL extensions according to their
official OpenGL extension names. This is intended to be used
only when one encounters severe stability problems caused by
buggy display drivers.
- VMDSHEARSTEREO :
Enable the use of an alternative perspective projection mode
which may result in improved stereoscopic display. Uses the
shear-matrix stereo formulation rather than eye rotation.
- VMDSIMPLEGRAPHICS :
Forces VMD to use absolutely minimalistic graphics features with no
use of OpenGL extensions. Essentially, nothing but bread-and-butter
vertex arrays and immediate mode rendering will be used. This mode
is intended to be used only when one encounters severe stability
problems caused by buggy display drivers.
- VMDWIREGL :
This environment variable disables several graphics features which
are unsupported (or poorly supported) by WireGL and Chromium.
This variable will be superceded with a more general
implementation in a future release.
- VMDOPTIXDEVICE
This environment variable limits VMD to performing
OptiX GPU-accelerated ray tracing on a specific GPU.
- VMDOPTIXDEVICEMASK
This environment variable limits VMD to performing
OptiX GPU-accelerated ray tracing on a specific subset
of GPUs, based on a hexadecimal mask. For example, to
allow rendering on only the first two GPUs, one would
set the mask to 0x3; to use only the second GPU, the mask
would be set to 0x2.
- VMDOPTIXNODISPLAYGPUS
This environment variable limits VMD to performing
OptiX GPU-accelerated ray tracing on GPUs that are not
attached to a display, to prevent long-running batch mode
OptiX renderings from interfering with interactive
VMD sessions or other desktop applications.
- VMDOPTIX_CLUSTER
This environment variable sets the remote access URL for
VMD OptiX renderings on remote NVIDIA VCA clusters.
- VMDOPTIXVCACONFIG
This environment variable selects the VCA cluster rendering
configuration index for VMD OptiX renderings on remote
NVIDIA VCA clusters, e.g., to favor increased image-space
parallel decomposition, or conversely for increased stochastic
sampling performance.
- VMDOPTIXVCANODES
The number of VCA cluster nodes to request for the interactive
VMD OptiX rendering session.
- VMDOPTIX_USER
This environment variable sets the remote access user name for
VMD OptiX renderings on remote NVIDIA VCA clusters.
- VMDOPTIX_PASSWD
This environment variable sets the remote access password for
VMD OptiX renderings on remote NVIDIA VCA clusters.
- VMDOPTIXBITRATE
This environment variable controls the bitrate used for remote
video streaming when VMD performs interactive ray tracing
on a remote NVIDIA VCA cluster. A good typical value for
high resolution, e.g., 4K images would be 15000000.
- VMDOPTIXBUILDER
This environment variable allows the default fast-but-memory-intensive
``Trbvh'' acceleration structure to be overridden by ``MedianBvh''
or other algorithms that aren't as fast, but require
much less GPU memory when rendering hundreds of millions of
objects that could otherwise cause GPU out-of-memory errors.
- VMDOPTIXIMAGESIZE
This environment variable allows the user to forcibly override
the resolution of the images to be rendered, ignoring the
incoming image height and width parameters VMD would normally use.
This variable is particularly useful when combining interactive
ray tracing with VR HMDs, where the ray traced image dimensions should
generally be more than
higher horizontal resolution than
the VR HMD display, and at least
higher vertical resolution.
- VMDOPTIXAOMAXDIST
This environment variable specifies a maximum occlusion distance
in eye coordinates, rather than the default of infinity,
for use when computing the ambient occlusion factor for a hit point.
By setting this to a small to moderate value, the interior region of
closed structures such as virus capsids will be lit with soft shadows
as they would with conventional AO, both on the interior and exterior.
Without the reduced occlusion distance cutoff, closed surfaces would
fall entirely into shadow.
- VMDOPTIXHEADLIGHT
This environment variable enables a positional light that is
always located at the center of projection, useful for interiors
of virus capsids and the like.
- VMDOPTIXDOMEMASTER
This environment variable allows the user to forcibly override the
currently active VMD 3-D projection mode
(only ``Orthographic'' or ``Perspective'' are currently implemented in
the OpenGL-based renderer), allowing the OptiX ray tracer to generate
hemispherical images for so-called ``fulldome'' projection systems such
as those typically used in digital planetariums.
- VMDOPTIXEQUIRECTANGULAR
This environment variable allows the user to forcibly override the
currently active VMD 3-D projection mode
(only ``Orthographic'' or ``Perspective'' are currently implemented in
the OpenGL-based renderer), allowing the OptiX ray tracer to generate
omnidirectional VR movies, e.g. for YouTube.
- VMDOPTIXSTEREO
This environment variable allows the user to forcibly override the
currently active VMD stereoscopic 3-D projection mode
allowing the OptiX ray tracer to generate stereoscopic
omnidirectional VR movies, e.g. for YouTube.
- VMDOSPRAYAOMAXDIST
This environment variable specifies a maximum occlusion distance
in eye coordinates, rather than the default of infinity,
for use when computing the ambient occlusion factor for a hit point.
By setting this to a small to moderate value, the interior region of
closed structures such as virus capsids will be lit with soft shadows
as they would with conventional AO, both on the interior and exterior.
Without the reduced occlusion distance cutoff, closed surfaces would
fall entirely into shadow.
- VMDOSPRAYMPI
This environment variable enables the use of the MPI distributed memory
rendering mode of OSPRay if it was compiled into the OSPRay library
in use by VMD.
- VMDOSPRAYIMAGESIZE
This environment variable allows the user to forcibly override
the resolution of the images to be rendered, ignoring the
incoming image height and width parameters VMD would normally
use. This environment variable makes it easy to renderer very
large images without changing the VMD display resolution.
Next: Startup Files
Up: Customizing VMD Sessions
Previous: VMD Command-Line Options
Contents
Index
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