Environment Variables

Environment variables can be set from a shell prompt with shell commands such as setenv (see the documentation of your shell) before mental ray, ivray, or the application that mental ray is built into, is started from the same shell. Environment variables set after mental ray is started, or set from a different shell, have no effect. mental ray will work without any environment variables, except that the .rayrc startup script may not be found if MI_ROOT is undefined.

DISPLAY

The Unix X11 display to be used for OpenGL acceleration.

HOME

Unix home directory, for finding the user's local .rayrc file.

HOMEDRIVE

Windows NT home drive, such as C:.

HOMEPATH

Windows NT home directory. mental ray will try to load %HOMEDRIVE%/%HOMEPATH%/rayrc.

MI_CG_FRAGMENT_PROFILE^3.4

Pass this profile name to the Cg compiler when compiling hardware shaders, instead of the profile matching the graphics hardware rendered on. This is useful in conjunction with the -hardware_echo command-line option to "cross-compile" shaders.

MI_HWDISPLAY^3.4

Overrides DISPLAY. This is useful if mental ray is run on one machine, where all graphical user interfaces are shown (so DISPLAY must point to the local host), but the local host does not have sufficient hardware rendering capacity so mental ray offloads it to another host, pointed to by MI_HWDISPLAY. This kind of remote hardware rendering incurs extra networking overhead but allows multiple desktop clients to share a fast hardware rendering server. It is not necessary for mental ray to be installed on the server, and no extra license is used. However, both the client and server hosts must have compatible OpenGL and OpenGL extension versions.

MI_IVRAY_OPTIONS

Extra options inserted by the Inventor version of mental ray.

MI_LIBRARY_PATH

Another search path, used for link commands.

MI_RAY_INCPATH

A colon-separated or semicolon-separated list of paths to search for files included with the $include command.

MI_RAY_OPTIONS

Extra options that are inserted by mental ray before the options on the command line. This is commonly used for options such as -xcolor.

MI_RAY2_SERVICE

The IP service that mental ray uses to contact slaves on other machines. The default is mi-ray2 for mental ray 2.x and mi-ray3 for mental ray 3.x. On Unix, service names are defined in /etc/services or in the services NIS map.

MI_RAY_SERVICE

If the previous variable is not defined, this one is used instead. This makes mental ray 2.x compatible with mental ray 1.9 while allowing both to coexist on the same machine. The default is mi-ray.

MI_RAY_SUBSTITUTE

An optional list of blank-separated substitution instructions, each in the form /search/replace/. Any other character besides / will also work.

MI_RAY_SWAPDIR

A swap directory where mental ray can put scene elements when it runs out of memory. This can be useful for large static scenes, where the scene file itself is large. mental ray generally swaps more efficiently than the operating system.

MI_RAY_SWAPLIMIT

The maximum number of bytes to write into the swap directory. A value of 0 turns off swapping.

MI_ROOT

The directory that mental ray searches for configuration files such as rayrc.

MI_STACKSIZE

New thread stacks will be created with this size in kilobytes if defined. The default is 16384 (16 MB) on Unix and 4096 on Windows NT. 4096 is nearly always sufficient except when very complex recursive shaders are used.

MI_TEX_LOOKUP_LOCAL

This variable can be set in network parallel rendering in order to look up and remap texture file paths on the individual rendering hosts instead of on the master host only. This allows to locate textures on the slave machines at a different file system path than on the master host.

Note that MI_TEX_LOOKUP_LOCAL should be set on all rendering hosts, not just the master.

Note also that this also causes file names to be echoed in the .mi format without performing file path substitutions.

SI_LOCATION

The directory of the linktab.ini file, which is used by the Softimage|3D application for path mapping.

TMPDIR

A directory for temporary code or object files to be compiled or linked. The default is /usr/tmp on Unix and the current directory on Windows NT.

USER

The current user name. It is stored in RLA image file headers, and is optional.

Registry lookups of the form $var return the value of the environment variable var. mental ray 3.4 allows
$?var, which returns 1 if the environment variable var exists and 0 otherwise.