Houdini 17.0 Reference

Environment variables

See how to set environment variables.

Variables

  • HOUDINI_AUTHOR

    Controls the username and machine name used when saving HDAs and hip files. Normally your login name and hostname are used, but setting this to myself@mydomain will use a user name of myself and a hostname of mydomain instead.

  • HOUDINI_DISABLE_CONSOLE

    If set, disables creation of floating consoles on Windows machines.

  • HOUDINI_TEXT_CONSOLE

    If set, instead of creating a floating console, a normal window shell will be created on NT machines.

  • HOUDINI_WINDOW_CONSOLE

    On the Windows operating system, the setting of this environment variable will force the creation of a floating console regardless of whether its output is redirected. This is only necessary for broken shells that incorrectly start up Houdini window applications with redirected output. At the time of this writing, only Cygwin-compiled shells require this.

  • HOUDINI_VERBOSE_ERROR

    Print out unexpected file save errors to the console as well as displaying them in error boxes.

  • HOUDINI_DISABLE_FILE_LOAD_WARNINGS

    If set, suppresses the dialog that displays warnings encountered while loading a file.

  • HOUDINI_OLD_SPINNER

    If set, the old style interrupt dialog graphic will be used (i.e. the spinning pie).

  • HOUDINI_OLD_CONST_BEHAVIOUR

    If set, the old behavior dealing with constant() expression segments is used instead. The old behavior allows changing the value of a constant() expression channel segment at any given frame within it, not just at its boundaries.

  • HOUDINI_SHOW_OLD_RENDER_PROPERTIES

    If set, render properties from previous releases will be displayed.

  • HOUDINI_SHOW_OLD_SHOPS

    If set, SHOPs from previous releases will be displayed.

  • HOUDINI_DISABLE_CPUID

    Obsolete control.

  • HOUDINI_DISABLE_MMX

    If set, disable MMX support for COPs and VEX. This also disables XMMX and SSE. This will reduce COPs processing speed by about 30%.

  • HOUDINI_DISABLE_XMMX

    If set, disable Extended MMX support for COPs and VEX. Extended MMX is implemented in the original Athlons and Pentium IIIs. This also disables SSE. This will reduce COPs processing speed by about 20%.

  • HOUDINI_DISABLE_SSE

    If set, disable SSE support for COPs and VEX. SSE is implemented in Pentium IIIs and higher and Athlon XPs (not the original Athlons). This will reduce COPs processing speed by about 10%.

  • HOUDINI_DISABLE_3DNOW

    If set, disable 3DNow support for COPs and VEX. 3DNow is available in AMD Athlon and Cyrix CPUs. 3DNow is not used if the CPU supports SSE (which is any Athlon XP, MP, 64 or Opteron).

  • HOUDINI_DISABLE_AVX

    If set, disable use of AVX processor instructions (where available). AVX instructions are present starting with Intel Sandy Bridge (released Q1 2011) and AMD Bulldozer (released Q4 2011) processors.

  • HOUDINI_DISABLE_JEMALLOCTEST

    If set, disable the test to see if jemalloc has successfully been loaded. On platforms that expect jemalloc, failure to link it will result in memory fragmentation and poor performance. Thus, a warning will be printed. However, it may be this is an intentional override, in which case setting this environment variable will suppress the warning.

  • HOUDINI_OSX_SWAP_DEL_AND_BACKSPACE

    On Mac OS X, when this variable is set the meaning of the keyboard 'delete' and 'backspace' keys are interchanged.

  • HOUDINI_ANONYMOUS_STATISTICS

    If set to 1, this will forcibly allow Houdini to gather and send anonymous usage statistics to help improve the product. Setting to 0 will disable statistic collection. The default of -1 will use the anonymous usage statistics settings in the preferences.

  • HOUDINI_ANONYMOUS_STATISTICS_UPLOAD_ERRORS

    If set, Houdini will print errors to the console when Houdini encounters network or server errors when attempting to upload anonymous usage statistics. By default, Houdini will not print anything if these errors occur.

  • HOUDINI_STATS_API_URL

    This variable controls which web URL Houdini sends anonymous usage statistics to. The default value is http://www.sidefx.com/stats/api.

  • HOUDINI_NO_START_PAGE_SPLASH

    If set to 1, Houdini will not attempt to open the Start Here splash page or the page that asks permission to turn on anonymous usage statistics.

  • HOUDINI_CASE_SENSITIVE_FS

    If set to 1, this causes Houdini to treat the file system as case-sensitive. This value defaults to 0 for Windows and Max OS X. For all other platforms, it defaults to 1.

  • HOUDINI_COREDUMP

    Setting this environment variable to 1 is useful for debugging HDK crashes. On Unix systems, Houdini will attempt to dump a core file instead of simply exiting on the SIGILL, SIGEMT, SIGBUS or SIGSEGV signals. Please see signal(5) for more information. On Windows, this will enable just in time debugging for debuggers such as Visual Studio.

  • HOUDINI_NO_ENV_FILE

    If set, Houdini will not load the $HOUDINI_USER_PREF_DIR/houdini.env file. This allows large facilities with standard environments to disable the houdini.env file by setting this variable in the script which they use to launch Houdini.

  • HOUDINI_NO_ENV_FILE_OVERRIDES

    This environment variable is similar to HOUDINI_NO_ENV_FILE, but is less extreme. Setting this stops the user from being able to override existing variables in their houdini.env file. If they try to do so, a warning will be printed.

  • HOUDINI_NO_LEGACY_MENUS

    When set, Houdini will not load the old MainMenuMaster, MaindMenuEscape, and MainMenuCommon menu files. It will only use the new MainMenuMaster.xml, MainMenuEscape.xml, and MainMenuCommon.xml.

  • HOUDINI_DSO_ERROR

    Determines if DSO/DLL errors on plug-ins will be printed out to the console. This can help in debugging custom operators.

    By default this is disabled.

    The existence of the variable in the environment (or setting its value to 1) will cause dynamic linking errors to be output.

    Setting the value to 2 will cause more verbose errors to be printed.

    Setting the value to 3 will cause all DSO related messages to be printed.

  • HOUDINI_DSO_DEEPBIND

    Only applicable On Linux. If set to 1, then all dynamically loaded DSO will be loaded using RTLD_DEEPBIND.

  • HOUDINI_DSO_EXCLUDE_PATTERN

    If set, this specifies a glob pattern that is used to exclude matching DSO/DLL files. The precise accepted syntax is as follows:

    • If it begins with a '/', then it matches at the beginning, else the pattern starts matching at any path component.

    • * matches any path component, but stops at slashes.

    • ** matches anything, including slashes.

    • ? matches any character except a slash (/).

    • [...] matches one of the enclosed characters, eg. [abc]

      • - within [...] denotes a character range, eg. [a-c]

      • If first character after [ is ! or ^, then it matches anything except the enclosed characters.

    • {x,y} matches the any of the comma(',') separated patterns within

  • HOUDINI_CPP_EXPAND_PRAGMA

    Determines whether the C pre-processor will perform macro expansion on #include, #sinclude, and #pragma statements.

  • HOUDINI_ENABLE_UNDO_BUG_NOTIFY

    If set to 1, this environment variable enables verbose output for potential undo bugs as they occur in Houdini.

  • HOUDINI_TIFF_BOTTOMLEFT

    Older versions of Houdini generated TIFF files with the first scanline of data representing the bottom of the image. This control can be turned on to replicate the behavior of older versions of Houdini.

  • HOUDINI_TIFF_SAMPLEFORMAT

    If set, the TIFF SAMPLEFORMAT tag will be output in all cases. This may cause older versions of the TIFF library to print warnings/errors about unknown tags.

  • HOUDINI_DISABLE_IMAGE_DSO

    If set, no custom image formats will be loaded. Only built-in formats will be installed.

  • HOUDINI_THREAD_IMAGE

    If set, some old-style compositing operations will be multi-threaded. On some platforms, this can provide a performance boost. However, on other platforms, this can cause a performance hit. This also affects Houdini applications like ipaint.

  • HOUDINI_LMINFO_VERBOSE

    Typically, Houdini will print out warnings at start-up time if licenses are due to expire shortly. If this control is set to 0, then no warnings will be printed out when applications start.

  • HOUDINI_NOHKEY

    Setting this environment variable will prevent Houdini from launching the apprentice license auto-installer and the license administrator when a license check fails.

  • HOUDINI_NOHKEY_APPRENTICE

    Setting this environment variable will prevent Houdini from launching the apprentice license auto-installer but will cause it to immediately launch the license administrator when a license check fails.

  • HOUDINI_NO_ASSET_INSTANTIATION

    Setting this environment variable will prevent Houdini from auto-instantiation when importing assets.

  • HOUDINI_JITTERY_CAMERA

    Setting this environment variable will prevent the direct assignment of the camera transform to the GL view transform. This will cause the camera to jitter in some cases. It, however, fixes reversed-perspective problems with the ES Tornado 3000 video card.

  • HOUDINI_VEX_DISABLE_AUTO_FOLDING

    Disables a specific optimization in Mantra/VEX which tries to selectively retain parameters to the VEX code, so that the same optimized code can be re-used between multiple instances that have different parameter values. If this optimization is off, then any VEX code that is instantiated multiple times with different parameter values, will have each instance treated as a unique optimization.

  • HOUDINI_VEX_RETURNBYREFERENCE

    In very old code, VEX would allow functions that computed a single value to also pass the return value by reference (e.g. sin(result, value) instead of result = sin(value)). This form of the function was marked as deprecated over 5 years ago and is now no longer allowed. Enabling this variable will re-instate the deprecated functions.

  • HOUDINI_VEX_PROFINFO_HTML

    If this variable is set, the VEX profiling information will be output using HTML instead of text.

  • HOUDINI_VEX_DISABLE_INSTANCE_CACHE

    Disables global caching of VEX shaders for the SOP and POP contexts so that shader-local data (such point clouds generated with pcgenerate) are regenerated with each cook of that operator.

  • HOUDINI_VEX_DISABLE_JIT

    Disables just-in-time compilation of VEX shader fragments to native machine code. This variable is still used, but is deprecated in favor of HOUDINI_VEX_JIT_OPTIMIZE.

  • HOUDINI_VEX_JIT_OPTIMIZE

    Specify JIT optimizations for VEX compilation. The string for this variable is a comma separated list of various options. If the option is found in the string. If the option token is found, the flag will be turned off. The flag can be turned off by prefixing the token with "no-". Alternatively, the value for the flag can be specified with the suffix "=value".

    For example

    • "native": Enable native JIT code generation

    • "no-native": Disable native JIT code generation

    • "native=on": Enable native JIT code generation

    • "native=off": Disable native JIT code generation

    Currently the following options are recognized

    • "cache" - Enable JIT specialization cache (default ON)

    • "native" - Enable native JIT code generation (default ON)

    • "global" - Perform global optimization across import calls (default ON)

  • HOUDINI_VEX_ASSERT

    Sets the behavior for the VEX assert_enabled() function. If the variable is set, the assert_enabled() function returns true. This has the effect of enabling the assert() macro (defined in assert.h).

  • HOUDINI_VEX_MODULECACHESIZE

    Sets the number of LLVM modules cached by VEX. Each cached module consumes some memory, but can save re-compiles if the same shader is used multiple times. A value of -1 indicates that the module cache will be unbounded.

  • HOUDINI_VEX_MEMORYCACHESIZE

    For efficiency, VEX has it’s own memory allocator. This variable controls the cache size for in MB each VEX variable type. The cache is split across threads, so machines with more cores may require larger cache sizes. This typically comes into play when there are large arrays being processed in VEX.

  • HOUDINI_MAXTHREADS

    Controls the maximum number of threads to use for compute-intensive operations in Houdini.

    The default of 0 means to use all available processors.

    Positive values will limit the number of threads that can be used. A value of 1 will disable multithreading entirely (limiting to only one thread). Positive values will be clamped to the number of CPU cores available.

    If the value is negative, the value is added to the maximum number of processors to determine the threading limit. For example, a value of -1 will use all CPU cores except 1.

    This control can be overridden by the -j option to most applications.

  • HOUDINI_MAXSPUS

    Controls the maximum number of SPUs to use in Cell/BE releases of Houdini. The default of -1 means to use all available SPU resources, while a value of 0 will disable SPU use entirely. Positive values will clamp the number of SPUs that can be used.

  • HOUDINI_USE_HFS_PYTHON

    Note

    This variable is no longer used.

    Houdini defaults to loading the Python library that is shipped in $HFS. You can instruct Houdini to load a different Python library by modifying the library search path in your operating system (Mac and Linux only). You may want to do this if there are 3rd-party modules installed in a different Python distribution that you wish to make available in Houdini.

    On Linux set the LD_LIBRARY_PATH environment variable to include the directory containing the Python library before launching Houdini.

    For example, in a terminal you can run:

    export LD_LIBRARY_PATH=/path/to/python/lib
    
    cd /opt/hfsX.Y.ZZZ
    source ./houdini_setup
    
    houdini
    

    You can alternatively set LD_PRELOAD instead of LD_LIBRARY_PATH if you want to load the Python library but not any unwanted libraries that are in the same directory.

    For example:

    export LD_PRELOAD=/path/to/python/lib/libpython2.7.so.1.0
    
    cd /opt/hfsX.Y.ZZZ
    source ./houdini_setup
    
    houdini
    

    Similarly on Mac set the DYLD_LIBRARY_PATH environment variable to include the directory containing the Python framework library. When using DYLD_LIBRARY_PATH you must launch the Houdini executable in the application bundle instead of the executable in $HFS/bin.

    For example, in the Houdini Terminal you can run:

    export DYLD_LIBRARY_PATH=/System/Library/Frameworks/Python.framework/Versions/2.7
    
    $HFS/Applications/Houdini\ FX\ X.Y.ZZZ.app\Contents\MacOS\houdinifx
    

    You can alternatively set DYLD_INSERT_LIBRARIES instead of DYLD_LIBRARY_PATH to load the Python framework library.

    For example:

    export DYLD_INSERT_LIBRARIES=/System/Library/Frameworks/Python.framework/Versions/2.7/Python
    
    $HFS/Applications/Houdini\ FX\ X.Y.ZZZ.app\Contents\MacOS\houdinifx
    
  • HOUDINI_PYTHON_VERSION

    Note

    This variable is no longer used.

  • HOUDINI_PYTHON_BIN

    Note

    This variable is no longer used.

    If you are loading a different Python library into Houdini (see note for HOUDINI_USE_HFS_PYTHON) and you need to additionally set the Python prefix path then instead of setting HOUDINI_PYTHON_BIN, set the PYTHONHOME environment variable.

  • HOUDINI_PYTHON_LIB

    Note

    This variable is no longer used.

    See the note for HOUDINI_USE_HFS_PYTHON for instructing Houdini to load a different Python library.

  • HOUDINI_OGL_MAX_GL_VERSION

    By default this is zero, indicating that Houdini should use all available features that the OpenGL driver provides. It can be set to any OpenGL version (major.minor, like "2.1") and only those OpenGL features that were part of the OpenGL core at that version will be enabled.

  • HOUDINI_OGL_ENABLE_TEXTURE_SEQUENCES

    Defining this variable enables the AGP texturing with large texture sequences, which may cause the X server seizing when the application quits (observed on nVidia cards with drivers 7174 and less). When this variable is not defined, Houdini deletes last raster texture before using a new one.

  • HOUDINI_OGL_DUMP_SHADER_ERRORS

    If present, GLSL compilation errors will be dumped to the console when encountered. This should only be used for debugging purposes.

  • HOUDINI_OGL_CORE_PROFILE

    If set to 1, the OpenGL core profile will be used. On Windows and Linux, this can be set to 0 to use the OpenGL Compatibility profile to allow OpenGL 1.x and 2.x API calls and shaders. OSX does not offer the compability profile with a OpenGL 3.2+ context, so this variable has no effect on OSX (Core profile is always used on OSX). The default is 0 on Windows and Linux, and 1 on OSX. If a Compatibility profile fails to provide OpenGL 3.2 or higher, Houdini will attempt to use the core profile instead.

  • HOUDINI_ENABLE_RETINA

    If set to 0, turns off Houdini’s support for retina displays under OSX. This will cause Houdini to act as if the display has half the resolution it actually has, resulting in a slightly pixelated interface. The advantage is that Houdini will also use less Video RAM for buffers, and run fewer pixels through the OpenGL shader pipeline, resulting in slightly increased performance. Linux and Windows are not affected by this setting.

  • HOUDINI_HIP_FROM_PATH

    When loading .hip files, force the Houdini HIP variable to the path of the HIP file specified rather than the HIP variable set inside hip file.

  • HOUDINI_PATHMAP

    This string defines multiple mappings represented as a Python-style dictionary. Mappings can map one directory to another directory. The key is the directory to map and the value represents the destination directory. For example:

    { "c:/temp": "/tmp", "/mnt/render": "//storage/share/render" }
    

    would create two directory mappings.

  • HOUDINI_COMPARE

    This string defines the command line to launch an external compare (diff) program. The following variables can be used when constructing the command line:

    "$OLDPATH"

    The currently saved op type

    "$NEWPATH"

    The modified op type data

    "$OLDTITLE"

    A title to use for the saved op type data instead of the temp file name (if your favorite differ supports this)

    "$NEWTITLE"

    A title to use for the saved modified op type data instead of the temp file name (if your favorite differ supports this)

    Use quotes generously to avoid problems with spaces.

  • HOUDINI_HIP_DEFAULT_NAME

    The default .hip file name. This defaults to "untitled.hip" and is used to initialize the HIP filename when starting a new Houdini session.

  • HOUDINI_DEFAULT_RENDERERS

    This variable provides a comma separated list of renderer(s) to use, overriding the preferences entirely. The format of the names should be the same as the render.activelist.val value in $HIH/houdini.prefs. Renderers enabled through this variable cannot be turned off through the preferences dialog.

  • HOUDINI_VIEW_RMAN

    This variable specifies the command to run when "View: RMan" is chosen from the viewport rendering menu.

  • HOUDINI_DEFAULT_RIB_RENDERER

    This variable is used in the creation script of the RIB output driver to create parameters appropriate for a particular RIB renderer. See $HH/scripts/out/targets.

  • HOUDINI_RIBSHADER_DIR

    This variable specifies the directory where Houdini should put RenderMan shaders compiled from VOP Networks. The default is $HOUDINI_TEMP_DIR. Only the compiled shader is placed in this directory. The source code for the shader is always put in $HOUDINI_RIBTEMP_DIR or $HOUDINI_TEMP_DIR.

  • HOUDINI_RIBTEMP_DIR

    This variable specifies the directory where Houdini should put RenderMan intermediate (i.e. source and error) files while generating compiled shaders from VOP Networks.

  • HOUDINI_THUMB_RENDER

    This provides a default value for the -r option of the thumbrender application. This application is used to render thumbnails for the SHOP palette.

  • HOUDINI_VIEW_MANTRA

    This variable specifies the command to run when "View: Mantra" is chosen from the viewport rendering menu.

  • HOUDINI_DISABLE_EXPORT_RENAME

    This variable disables the immediate recooking of exported CHOPs whenever a new node is created or when an existing node is renamed. For example, if you have a chop that is exporting to /obj/geo*, then it requires recooking if an object is renamed from /obj/foo to /obj/geo1. To disable this behavior, set this environment variable to 1.

  • MANTRA_FORCE_RAY

    Force mantra to use raytracing (same as -r option)

  • MANTRA_ENGINE_PROCEDURAL

    Specifies the default behavior for enabling the engine procedural in mantra. If the -e command line option isn’t specified on the command line, this setting determines how the engine procedural will enabled. Currently, the different possible values are "none", "basic" or "full". Note that "full" will cause mantra to consume an Engine license (not a Render license).

    Specifying the -e option on the mantra command line overrides this variable.

  • MANTRA_DISABLE_FOGBOX

    When rendering fog, mantra will create a matte shaded object automatically so the fog will be picked up in the background. Setting this variable disables this feature.

  • MANTRA_NONRAT_ERROR

    Normally, mantra will automatically convert texture files that are not in .rat format to .rat format internally - which can slow down render startup. To disable automatic conversion to .rat format and instead print out an error when textures are not in the native format, set this variable.

  • MANTRA_LINEAR_CREASES

    Revert to the subdivision crease algorithm used in Houdini 12.5 and earlier. Subdivision creases in mantra now use Pixar-style creasing for Houdini 13 and later.

  • HOUDINI_RMAN_INCLUDE_FIX

    Setting this variable will cause the order of pre/post includes to be different when generating RIB. This allows for proper motion blur of RiReadArchive geometry read using the include files.

  • HOUDINI_MI_DISABLE_FLIP_RMAP

    When auto-generating reflection maps for MentalRay, one of the images is flipped by default. Setting this variable will turn the flipping off.

  • HOUDINI_DISABLE_SOHO_SPOOLING

    When this variable is defined, interactive rendering from within Houdini will send data directly to the renderer over a pipe rather than first saving it to a temporary file and then spooling it to the renderer in a separate thread.

  • HOUDINI_MMB_PAN

    When this variable is defined, the mouse buttons are remapped so that the left button tumbles, middle mouse pans, and right mouse button zooms. This is the setting used in Houdini version 8.1 and earlier.

  • HOUDINI_DISABLE_SAVE_THUMB

    Disable saving of thumb-nails in .hip files. This makes .hip files smaller and faster to save/load.

  • HOUDINI_UI_COREDUMP

    Prevent Houdini from trying to saving a .hip file when a crash is detected. Instead, Houdini will simply crash.

  • HOUDINI_USER_PREF_DIR

    The directory to store user preference files. The value of this variable must include the substring __HVER__, which will be replaced at run time with the current MAJOR.MINOR version string. On Windows and Linux, this defaults to the expanded value of $HOME/houdini__HVER__. On Mac OSX, it will also use this default if the directory exists, else it uses the expanded value of $HOME/Library/Preferences/houdini/__HVER__.

  • HOUDINI_ENABLE_FPS_SCALE

    If enabled, it will stretch all keys in your animation so that the time at the start of the last keyframe is the total animation length when you change the frame rate of your animation. Usually, when you change your animation frame rate, the last keyframe will end up at a fractional keyframe of your new frame rate because each frame in Houdini is actually a (1/FPS) seconds in length. Note that when you do this, the actual timing of your animation will be changed when you modify your frame rate.

  • HOUDINI_LINUX_DOUBLE_CLICK_TIME

    Specifies the delay (in seconds) within which the mouse button needs to be clicked (and released) for the second time in order to consider it a double-click action.

  • HOUDINI_ENABLE_TABLET

    Enable Wacom tablet support on Linux and Windows. This defaults to 1.

  • HOUDINI_ENABLE_3DMOUSE

    Enable 3D mouse support. This defaults to 1.

  • HOUDINI_USE_NATIVE_FILE_CHOOSER

    This variable controls whether Houdini will use the file chooser dialogs provided by the operating system. By default Houdini will try to use them, but only on platforms on which Houdini supports native file choosers. If this variable is set to 0, Houdini will use own file browser dialogs. There are three levels that this variable can specify.

    0

    Only use Houdini’s own file choosers. This is the default behavior.

    1

    Houdini and MPlay will use native file choosers for their File > Open… items in their main menus. For any other file browsing, Houdini will use own file choosers.

    2

    If possible, Houdini will use native file choosers for browsing any file.

  • HOUDINI_MAX_FILE_HISTORY

    This variable controls the maximum number of items kept in the recent files history lists. Its value can range from 1 to 64 inclusively.

  • HOUDINI_X11_SYNCHRONOUS

    Force Unix X11 servers to be synchronous. If enabled, this may affect performance by slowing down redraws.

  • HOUDINI_VIEW_METACAM

    Obsolete control.

    Used to specify Houdini digital assets lockable to the view. Please, use the desired light or a camera as a "Representative" operator for the HDA, which can be specified in the Basic tab of the asset properties.

  • HOUDINI_SKIP_NAME

    Avoid printing viewport name in Houdini

  • HOUDINI_TOP_POS_SINGLE_PASS

    Set this environment variable to force only a single pass for drawing the wireframe outside of stamped projections in the TOP texture positioner view. Otherwise multiple passes are used to only draw the frame outside of the stamped projection.

  • HOUDINI_IPLAY_IP

    Force "ip" image device to use iplay instead of mplay. This behavior can be overridden using the HOUDINI_IP_COMMAND and HOUDINI_IP_COMMAND_FLIP controls.

  • HOUDINI_CONSOLE_LINES

    Number of lines to store in the Windows console

  • HSCRIPT_NO_HISTORY

    If this variable is defined, the script applications (hython and hbatch) and script panes will not store the line history. They will use standard input directly.

  • HOUDINI_INTERRUPT_THRESH

    Timeout in seconds before the interrupt dialog appears to interrupt long operations.

  • HOUDINI_TEX3D_USAGE

    Amount of memory used by 3D texture maps in VEX.

  • HOUDINI_RAT_USAGE

    Amount of memory used by RAT textures in Houdini and renders. This amount is specified in mega-bytes. For example, setting the control to 32 will limit Houdini/Mantra to use 32 Mb of RAM for RAT file texturing.

  • HOUDINI_RAT_FILES

    The maximum number of files held open by the Houdini texture engine for rendering or other applications.

  • HOUDINI_RAT_LOCALCACHE

    Specifies the size of the local texture disk cache in MB.

    When texture are stored on network drives, and there are more textures than will fit in memory (i.e. there’s texture cache thrashing), setting a local disk cache will cause discarded tiles to be written to a local disk file rather than having to be re-fetched over the network. This may improve performance on heavily loaded networks.

    The cache file is created in HOUDINI_TEMP_DIR (which should have enough space to store the cache file).

  • HOUDINI_RAT_OPTIMIZE_BANDWIDTH

    When textures are stored on network drives, Houdini/Mantra can attempt to optimize data transfer over the network. This control can be used enable/disable this behavior. The default behavior is to perform bandwidth optimization.

    This feature may not be supported on all operating systems.

  • HOUDINI_PTEX_USAGE

    Amount of memory used by .ptx textures in Houdini and renders. This amount is specified in mega-bytes. For example, setting the control to 32 will limit Houdini/Mantra to use 32 MB of RAM for .ptex files.

  • HOUDINI_PTEX_FILES

    Maximum number of files held open by the ptexture library in Houdini and renders.

  • HOUDINI_PTEX_WINDING

    Controls the expected orientation of ptexture faces. Setting the value to 1 will swap the u and v coordinate from the standard Houdini format, which is typically the expected orientation from other software packages. When 1 you won’t have to swap uv’s in shaders or SOPs.

  • HOUDINI_UVENLARGER_DIFFUSE_WRAP

    When set to 1, Diffuse Fill UDIM Post Process in Bake Texture will wrap diffusion across 0-1 boundaries, which can be help reduce visible seams if an edge of a polygon is touching the boundary in UV space, and texture is sampled at higher mipmap level with wrapped texture filter.

  • HOUDINI_MDISPLAY_WAIT_TIME

    Number of seconds to wait before deciding that iplay could not be started.

  • HOUDINI_OVERRIDE_XRES

    Specifies the horizontal resolution of your monitor in pixels. Houdini will not create any windows wider than the value specified here. You can use this value to force Houdini to only use a portion of your screen.

  • HOUDINI_OVERRIDE_YRES

    Specifies the vertical resolution of your monitor in pixels. Houdini will not create any windows taller than the value specified here. You can use this value to force Houdini to only use a portion of your screen.

  • HOUDINI_UISCALE

    This specifies a fixed scale factor to adjust the dots-per-inch Houdini uses for displaying ui. A value of 100 will provide the default of 85 dpi. A value of 200 will have all fonts and icons twice that size, and 50 will make them half that size. A value of -1 will cause the dpi to be calculated from the monitor’s dimensions and resolution, or by HOUDINI_OVERRIDE_*.

    By default the value is 100.

  • HOUDINI_SCRIPT_DEBUG

    If set, errors will be printed when loading dialog scripts and scripted operators.

  • HOUDINI_IMAGE_DEBUG

    If set, some image formats will be more verbose about errors encountered when saving/loading images. It’s possible that many false positives will be reported with this setting turned on, so it’s not recommended to have this enabled by default.

  • HOUDINI_TARGA_LINEAR

    Houdini defaults TARGA images to sRGB color space. However, older versions of Houdini expected TARGA format to be in linear space. Setting this variable will change the default color space for TARGA images to linear.

  • HOUDINI_ENABLE_EXR_TEXTURE

    When enabled (default on) this allows Houdini to access .exr files directly for texture evaluation. While convenient, this may have performance penalties if there are large filter areas. Disabling this will cause .exr files to be converted internally to .rat files for more efficient texture access. There is a cost (time and memory) to converting to .rat files.

  • HOUDINI_SCRIPT_LICENSE

    This variable is primarily used to determine which license should be used when using the hou module from a standard python shell. The license will determine which features are available in the hou module. It is recommended that you set this variable with os.environ, but you must do so before importing the hou module.

    Note that hython and hbatch will also use this variable. The hbatch and hython options will override this variable, though.

    Possible values of the variable are: "hbatch"

    Access to all of Houdini. Checks out for a Houdini Batch license, and if one could not be found, checks out an Houdini Master license.

    "hbatch -R"

    Same as "hbatch", but only checks for a Houdini Batch license. See the -R option in hbatch for more information.

    "hscriptexper"

    Access to all of Houdini, including the experimental parts. It uses a Houdini Master Experimental license.

    "hescape"

    Access to all the nodes that Houdini Escape has access to. uses a Houdini Escape license.

    "hescape -p"

    Access to all the nodes that Houdini Escape has access to, plus the third party rendering nodes. Uses a Houdini Escape license and a Plus license.

  • HOUDINI_RMAN_CURVE_STEP

    Obsolete control. Overrides the step size when writing RiCurve primitives for RIB. This is obsolete and may be removed in future versions. It has been replaced by the ri_curvestep detail integer attribute.

  • HOUDINI_DISABLE_ALEMBIC_INDEXED_ARRAYS

    Disable saving string attributes as Alembic indexed arrays. By default, Houdini will save strings as indexed attributes in cases where it makes sense. This option will disable this feature.

  • HOUDINI_ALEMBIC_OGAWA_STREAMS

    When doing threaded processing on Alembic Archives, use this many streams. The default of zero lets Houdini pick the optimal number, and 1 disables threaded processing of Alembic archives. Higher values enable threading but cause more open files, so it should generally not be set higher than the processor count.

  • MANTRA_BIAS_NORMAL

    Specifies that biasing for ray tracing operations in mantra should operate along the normal vector rather than along the outgoing ray.

  • HOUDINI_UI_QUEUE_SIZE

    Specifies the size of the UI event queue. Increasing this can help prevent queue overflows.

  • FPS

    This variable is used by iplay to set the default frames per second. It is automatically set by the OpenGL output driver.

  • HOUDINI_PERFORMANCE_SIZE

    Specifies the number of lines that the performance monitor keeps.

  • HOUDINI_ABEKAS_PAL_XRES

    Overrides the default resolution of the abekas image device.

  • HOUDINI_ABEKAS_PAL_YRES

    Overrides the default resolution of the abekas image device.

  • HOUDINI_GAUSS_EXP

    Specifies the exponent for the Gaussian filter kernel. This affects any Gaussian filtering (image scaling, rendering, etc.)

  • HOUDINI_MITCHELL_B

    Specified the B parameter of the Mitchell filter kernel. This affects any Mitchell filtering (image scaling, rendering, etc.)

  • HOUDINI_MITCHELL_C

    Specified the C parameter of the Mitchell filter kernel. This affects any Mitchell filtering (image scaling, rendering, etc.)

  • HOUDINI_CHOP_OLDNOISE

    The noise CHOP in Houdini5 and greater has a new method for computing random values. This produces different results than Houdini4, but is more consistent on different hardware platforms. If this variable is set, the noise CHOP in Houdini5 will generate same values as Houdini4.

  • HOUDINI_FULL_SHADERSTRING

    This variable determines whether shaders are output to mantra or prman with values set for all their parameters. If set to 0, then only parameters whose values are not at default are sent. This results in smaller IFD or RIB files. However, if the shader is changed without regenerating its corresponding .ds files, then the output might be wrong.

  • HOUDINI_TYPED_SHADERSTRING

    This variable determines whether the shader string output to prman contains only the parameters that are tagged with a type. If the variable is not set, then all parameters are included whether or not they have a script type information. Otherwise, if it is set, then shader string will contain only parameters that have an explicit script_ritype tag set.

  • HOUDINI_RSL_HASHING

    To prevent name collisions on .slo files, Houdini will normally do hashing on the SLO shader name. Mangling/hashing the shader name will help in cases where there are multiple shaders with the same name, but in different sub-networks. In addition, hashing will help when the same .hip file is being used to generate shader files on a shared network drive (preventing overwriting by separate Houdini processes).

    The value of this variable has different levels of name mangling.

    0

    Disable all mangling of names

    1

    Hash shader name with the operator path name and the Houdini process id.

    2

    Place shader in a sub-directory based on the .hip file name

    3

    Place each shader in a sub-directory based on the .hip file name and the operator’s full path.

  • HOUDINI_VOP_DEFINITIONS_PATH

    Defines the directory search path where Houdini looks for connector type definitions (such as new struct definitions). The default is to look in the vop subdirectory of HOUDINI_PATH directories.

  • HOUDINI_NO_DEFAULT_SHELF_TOOLS

    This variable, when set to non-zero, disables the automatic generation of the shelf tools for Houdini Digital Assets that don’t define any shelf tools (or explicitly removed all the tools from its tool section). Otherwise, when a digital asset is loaded, Houdini will generate a default tool that will allow the user to instantiate it from the shelf or the TAB menu.

  • HOUDINI_SHELF_EXCLUDE_DIRS_PATTERN

    If set, this specifies a regular expression that is used to exclude matching subdirectories when searching for shelf files.

  • HOUDINI_CHOP_LINEWIDTH

    This variable controls the line thickness in the CHOP viewer.

  • HOUDINI_CHOP_UNITS

    This sets the default parameter for the Units parameter of CHOPs. Valid values include: frames, samples, seconds.

  • HOUDINI_CHOP_IMAGE

    This variable can be set to point to an image file which is displayed when the CHOP viewer is disabled.

  • HOUDINI_COLOR_PICKER_GAMMA

    This variable specifies the gamma exponent for the device specific color correction of the color picker gadgets and color parameters.

  • HOUDINI_CINEON_WHITE_POINT

    Defines the white point for reading and writing Cineon files. This value is not used if a LUT file is used. It defaults to 685.

  • HOUDINI_CINEON_FILM_GAMMA

    Defines the film gamma for reading and writing Cineon files. This value is not used if a LUT file is used. It defaults to 0.6.

  • HOUDINI_CINEON_BLACK_POINT

    Defines the Cineon black point for reading and writing Cineon files. This value is not used if a LUT file is used. It defaults to 95.

  • HOUDINI_CINEON_FULL_RANGE

    If set, the generated LUT from the CINEON_WHITE_POINT and CINEON_FILM_GAMMA is not clipped above the white point; the full range of the Cineon data is preserved. Only used by the Houdini 4.0 Compositor.

  • HOUDINI_CINEON_RENDER_LUT

    Defines the default render LUT filename for reading and writing Cineon files.

  • HOUDINI_CINEON_PREVIEW_LUT

    Defines the default preview LUT filename for reading and writing Cineon files. Only used by the Houdini 4.0 Compositor.

  • HOUDINI_IMAGE_DISPLAY_GAMMA

    Defines the default gamma for Houdini (found in Edit > Color Settings), for displaying images in the composite view, render view, 3D viewport and MPlay.

  • HOUDINI_IMAGE_DISPLAY_LUT

    Defines the default display LUT for Houdini (found in Edit > Color Settings), for displaying images in the composite view, render view, 3D viewport and MPlay.

  • HOUDINI_OCIO_SRGB_FILE_COLORSPACE

    Sets the source colorspace for an sRGB file when loaded into MPlay.

  • HOUDINI_OCIO_FILENAME_COLORSPACE

    Enables detection of the OpenColorIO colorspace of an image file by looking at the filename itself. If set to 1, detection is enabled. The longest, rightmost string that matches a colorspace will be taken as the colorspace. If none are found, use Houdini’s heuristics for determining the colorspace (JPG is sRGB, EXR is linear, etc). If set to 2, detection occurs in the same way but when no colorspace is found, the "default" role defined by the OpenColorIO config.ocio file is used (OpenColorIO strict parsing). When set to 0, detection is not performed and Houdini’s native heuristics are used to determine the colorspace.

    This only has an effect if an valid OCIO environment variable is set.

  • HOUDINI_IMAGE_DISPLAY_OVERRIDE

    If set to 1, the HOUDINI_IMAGE_DISPLAY_GAMMA and HOUDINI_IMAGE_DISPLAY_LUT will always override the values stored in color.pref. When 0, these variables will only take effect if colors.pref is not present. Setting this to 2 will only allow gamma to override, and 3 only the LUT.

  • HOUDINI_IMAGE_INSPECT_LUT

    Defines the default inspect LUT filename for inspecting images in the compositor’s viewer and MPlay.

  • HOUDINI_AUTOCONVERT_IMAGE_FILES

    By default Houdini linearizes any non-linear image formats that it loads, and converts them from linear to the image format’s native colorspace when writing image files. This can be globally disabled by setting this variable to 0, though local options can still override it (icp -g auto, the Linearize Non-Linear Images in the File COP). This sets the initial default for those parameters. This should only be used if a LUT pipeline is handling the linearization of images. This should generally be used in conjunction with a HOUDINI_IMAGE_DISPLAY_GAMMA setting of 1.0.

  • HOUDINI_LOD

    This is an Level of Detail number, such as 0.01 or 1.0. It becomes the default LOD for new windows. Higher LODs will result in more accurate drawing of curves and surfaces, however at a corresponding cost in display speed. By default, it is set to 1.0. If you find yourself having to constantly change the View Parameter:Viewer:LOD setting, you might save some work by just making your default a better value.

  • HOUDINI_WF_GAMMA

    Specifies the gamma value written out to Wavefront .rla files.

  • EDITOR

    Houdini will use this variable to determine which external graphical editor to invoke when editing text. The editor should run in the foreground.

    If the VISUAL environment variable is set, then it is used instead of EDITOR and started as a graphical process. In other words, the VISUAL environment variable will override this and thus have no effect if VISUAL is also set. If both the VISUAL and EDITOR variables are not set, then a default editor (Windows Notepad, Mac OS X Text Edit, Linux GEdit) is used.

    This environment variable may be used by applications other than Houdini.

  • VISUAL

    Houdini will use this variable to determine which external editor to invoke when editing text.

    If this environment variable is not set, then the EDITOR environment variable is used. See the help for the EDITOR environment variable to see what are the defaults if both are not set.

    This environment variable may be used by applications other than Houdini.

  • HFS

    The path where Houdini is installed. Houdini reads the configuration information from $HFS/houdini.

  • SHELL

    When Houdini starts external applications, it uses the SHELL variable to determine how to start them. This may be used by applications other than Houdini.

  • HOME

    This variable determines your "home" directory. This may be used by applications other than Houdini. Houdini mostly uses files in $HOME/houdiniVERSION, where VERSION i the current version number (ie: $HOME/houdini6 or $HOME/houdini6.1).

  • HSITE

    The HSITE variable is a path to the site-specific Houdini configuration information. This allows a site to have a common set of defaults and files. It is, by default, in the HOUDINI_PATH between HOME and HFS. To change global configuration information, you should use this rather than editing the contents of $HFS/houdini.

    Like HOME, Houdini uses $HSITE/houdiniVERSION, where version is the current version number (ie: $HSITE/houdini16 or $HSITE/houdini16.1)

  • JOB

  • HOUDINI_TEMP_DIR

    Specifies a directory where Houdini will generate temporary files.

  • HOUDINI_UNDO_DIR

    Specifies a directory where Houdini will store undo information. If not specified, the temporary directory will be used.

  • HOUDINI_CONDENSE_HIP

    If this variable is set Houdini will attempt to make paths entered "friendly" by replacing portions of filename paths with .hip if it’s appropriate. This behavior is off by default.

  • HOUDINI_UNBUFFERED_STDINOUT

    If this variable is set, Houdini will not buffer the console’s standard input and output. When output is unbuffered, any output you write to the console (from C++, Python, etc.) will appear immediately, without you having to write a newline character or flush the output. This variable is similar to Python’s PYTHONUNBUFFERED variable.

  • HOUDINI_MESSAGE_COMMAND

    An external program which Houdini uses to display graphical messages.

  • HOUDINI_CONFIRM_COMMAND

    An external program which Houdini uses to display confirmation boxes.

  • HOUDINI_WEB_BROWSER_COMMAND

    An external program which Houdini uses to display web pages. For example "/usr/bin/firefox" on Linux or "c:/Progra~1/Mozill~2/firefox.exe" on Windows (though "c:\\\Progra~1\\\Mozill~2\\\firefox.exe" is also valid).

  • HOUDINI_TERMINAL_COMMAND

    An external program which Houdini uses as a terminal. For example the default "xterm" or "gnome-terminal".

  • HOUDINI_ERRORLOG_FILENAME

    If set to a valid file name, Houdini will log all errors of severity above HOUDINI_ERRORLOG_LEVEL to this file.

  • HOUDINI_ERRORLOG_LEVEL

    The minimum error level that Houdini will write to the error log file specified by HOUDINI_ERRORLOG_FILENAME. Valid values are integers between 0 (all errors will be logged) and 6 (nothing will be logged) inclusive. Default value is 3. Error levels are defined as follows: 1, message; 2, prompt; 3, warning; 4, abort operation; 5, fatal error.

  • HOUDINI_DEFAULT_TEXTURE_COLOR

    Specifies the default color to use when texture maps cannot be found while rendering. This can be specified as a single string containing four floating point numbers representing the red, green, blue and alpha components of the default color. For example:

    setenv HOUDINI_DEFAULT_TEXTURE_COLOR "0 0 0 0"

    to set it to zero black.

  • HOUDINI_DESKTOP_DIR

    This variable specifies the file path to the folder or the directory that is considered the user’s system desktop directory. This variable is used in the file chooser dialog to jump to the user’s desktop.

  • HOUDINI_VEX_DEFAULT_AMBIENT

    The default VEX ambient light shader. If no shader can be found for an ambient light source, this shader will be applied at render time.

  • HOUDINI_VEX_DEFAULT_LIGHT

    The default VEX light shader. If no shader can be found for a light source, this shader will be applied at render time.

  • HOUDINI_VEX_DEFAULT_MATTE

    The default VEX matte surface shader. This shader is used at render time to provide a background surface if there is fog applied to a scene.

  • HOUDINI_VEX_DEFAULT_SHADOW

    The default VEX shadow shader. If a light source is casting shadows, but no shadow shader is found, this shader is applied at render time.

  • HOUDINI_VEX_DEFAULT_SURFACE

    The default VEX surface shader. If no surface shader can be found, this shader will be applied at render time.

  • HOUDINI_VEX_DEFAULT_VOLUME

    The default VEX surface shader applied to volumes. If no surface shader can be found for an object, this shader will be applied at render time.

  • HOUDINI_OGL_DEBUG

    Starts Houdini with a debug GL profile, if supported by the OpenGL driver. This can be used to help debug GL render hooks in the HDK. The value specifies the level, which includes reporting from all levels below it. This information is provided by the OpenGL driver and requires the GL_ARB_debug_output extension. Messages are written to the standard error stream and prefixed with HOUDINI_OGL_DEBUG.

    0

    No debugging (default)

    1

    High priority messages only

    2

    Medium and high priorities

    3

    Low, medium and high priorities

    4

    All messages (notifications, low, medium and high priorities)

  • HOUDINI_OGL_DEBUG_EXCLUDE

    Excludes certain messages types from debug output when HOUDINI_OGL_DEBUG is enabled. Multiple message types and sources can be excluded, specified by whitespace-separated strings.

    error

    OpenGL Errors

    performance

    Issues affecting performance

    portability

    Legal uses of OpenGL on this platform that may not work on others

    undefined

    Use of OpenGL whose behavior is not defined by the OpenGL specification

    deprecated

    Use of OpenGL features that are deprecated (legacy)

    other

    Other miscellaneous messages

    annotation

    Houdini debug annotations

    group

    Houdini main rendering group annotations

    opengl

    Message originated from the OpenGL driver

    compiler

    Message originated from the GLSL compiler, or other compiler

    window

    Message originated from the Window Manager (WGL, GLX, AGL)

    houdini

    Message originated from Houdini

    thirdparty

    Message originated from outside OpenGL, Houdini or Window Manager

  • HOUDINI_OGL_PICKBUFFER_PATH

    For debugging viewport picking. Specifies a directory where pick buffers should be written out as image files for later inspection. Use the HOUDINI_OGL_FILECOUNT variable to control the number of files to write before looping around to overwrite existing files.

  • HOUDINI_OGL_SNAPBUFFER_PATH

    For debugging viewport snapping. Specifies a directory where snap buffers should be written out as image files for later inspection. Use the HOUDINI_OGL_FILECOUNT variable to control the number of files to write before looping around to overwrite existing files.

  • HOUDINI_OGL_BEAUTY_PATH

    For debugging viewport drawing. Specifies a directory where geometry draw should be written out as image files for later inspection. Use the HOUDINI_OGL_FILECOUNT variable to control the number of files to write before looping around to overwrite existing files.

  • HOUDINI_OGL_VIEWPORT_PATH

    For debugging viewport drawing. Specifies a directory where final viewport buffers should be written out as image files for later inspection. Use the HOUDINI_OGL_FILECOUNT variable to control the number of files to write before looping around to overwrite existing files.

  • HOUDINI_OGL_FILECOUNT

    Controls the number of images to keep when writing out OpenGL buffers with the HOUDINI_OGL_SNAPBUFFER_PATH, HOUDINI_OGL_PICKBUFFER_PATH and HOUDINI_OGL_BEAUTY_PATH values.

  • HOUDINI_COPY_SUFFIX

    When copy/pasting, this variable can be used to create user-specific temporary files.

  • HOUDINI_OPNAMESPACE_HIERARCHY

    Defines the operator type namespace hierarchy as a space-separated list of namespace names and/or operator type names, sorted according to the descending preference order. This hierarchy is used to resolve any ambiguous operator type names used in scripts (eg, in opadd command) A few examples:

    Given hierarchy "userB userA" and available operators userA::hda and userB::hda, the command "opadd hda" will choose userB::hda.

    Given hierarchy "Sop/hda::2.0" and available operators hda::2.0 and hda::3.0, the command "opadd hda" will choose hda::2.0.

    Given hierarchy "Sop/hda::" and available operators hda and hda::1.0, the command "opadd hda" will choose hda.

  • HOUDINI_RMAN_CURVE_BASIS

    Obsolete control. Specify the curve interpolation when generating RiCurve primitives in a RIB stream. This should be one of "linear" or "cubic". This is obsolete and may be removed from future versions. It has been replaced by the ri_curveinterpolation detail string attribute.

  • HOUDINI_COP_DISK_DEFAULTNAME

    Obsolete control

  • HOUDINI_COP_ENSURECOLORPLANES

    Forces each COP to generate C and A color planes. Provides backwards compatibility with old versions of Houdini.

  • HOUDINI_MANTRA3_SHADOW

    Obsolete control

  • HOUDINI_MANTRA3_REFLECT

    Obsolete control

  • HOUDINI_RI_SHADERPATH

    When the RSL shader search path is not specified on the RIB output driver in the Shader Path parameter (or if the parameter does not exist), then this environment variable is checked. If this variable exists, then its value will be output to the RIB stream. If the variable doesn’t exist, a specially constructed search path will be output to the RIB file. That specially constructed path consists of the current directory, followed by the list of ri_shader sub-directories in HOUDINI_PATH, followed by the RenderMan’s default shader search path.

  • HOUDINI_RI_RIXPLUGINPATH

    When the RIS shader search path is not specified on the RIB output driver in the Rix Plugin Path parameter (or if the parameter does not exist), then this environment variable is checked. If this variable exists, then its value will be output to the RIB stream. If the variable doesn’t exist, then no RIS plugin path will be output to the RIB file.

  • HOUDINI_FILE_VIEWER

    Specify an external application to view files.

  • HOUDINI_CHECK_XFORM

    When generating scripts for renderers, if this variable is set, the transforms on objects will be tested to see if they are singular (i.e. whether there are zero scales). If the transform is singular, the object will not be output.

    The value of this variable is the threshold at which the transform is considered zero. Thus, the variable should be set to some very small floating point number.

  • HOUDINI_STPATH

    Specify a path to search for the source to a shader when editing shader code from pop-up dialog scripts.

  • HOUDINI_STEDIT

    Specify an external application to edit shaders with.

  • HOUDINI_DOUBLEBUFFER

    This variable can be set to either ON or OFF. It will force houdini to run in either single or double buffer mode.

  • HOUDINI_WORKSHEET_BOXPICK

    This environment variable is used to override using the left mouse button for box picking in the network worksheet. Can be set to either "middle" or "right".

  • HOUDINI_DEFOPTYPEPREFIX

    When you convert a subnet into a new operator type, this prefix, if present, will be used for guessing what the basename of the new operator should be. If not present, the username is used.

    For example, setting this to "foobar_" will ensure all operators created will have their basename type prefixed by foobar_. This can be used to ensure conflicts don’t occur with other projects operators.

  • HOUDINI_VEX_COMPILER

    External application used for compiling VEX code. Usually "vcc".

  • HOUDINI_ABEKAS_LOGNAME

    Specify the user name for logging into an Abekas frame recorder.

  • HOUDINI_ABEKAS_LOGPASSWD

    Specify the password for logging into an Abekas frame recorder.

  • HOUDINI_MD_COMMAND

    Specify the external application used by the md image device to read images from stdin and display them in a persistent frame buffer device (i.e. MPlay).

  • HOUDINI_MD_COMMAND_FLIP

    Specify the external application used by the md image device to read images from stdin and display them upside down in a persistent frame buffer device (i.e.

  • HOUDINI_MPLAY_LOCKPATH

    Specify a directory to create the MPlay lockfiles. These files will normally be created in the user’s HOME directory. The value of this variable should point to a directory where lockfiles can be created (i.e. /tmp or c:/temp).

  • HOUDINI_EXTERNAL_HELP_BROWSER

    When this variable is defined, Houdini will launch a default web browser to display the help documents externally. This applies only to the Houdini’s floating help browser pane; the embedded panes will still show the Houdini’s own help browser. This environment variable is useful to display html content which cannot be normally displayed in the standard help browser (such as https).

  • HOUDINI_IP_COMMAND

    Specify the external application used by the ip image device to read images from stdin and display them in a viewer (i.e. iplay).

  • HOUDINI_IP_COMMAND_FLIP

    Specify the external application used by the ip image device to read images from stdin and display them upside down in a viewer (i.e. iplay).

  • USER

    Internally, Houdini will to override this variable with information from the login session. This variable represents the name of the user logged in.

  • HOUDINI_OS

    The OS that Houdini believes it’s running on. Possible values of this variable are currently defined as "Windows", "Linux", or "MacOS".

  • HOUDINI_UI_RESOURCES

    An application variable which specifies the name of the resource file used for Houdini. It is rare that you would need to change this variable, and incorrectly setting it will cause the graphical Houdini applications to fail on startup.

  • HOUDINI_PATH

    The path of directories where Houdini looks for configuration files.

  • HOUDINI_OTL_PATH

    This path is not used directly by Houdini. It is used to provide default values for the HOUDINI_OPLIBRARIES_PATH and HOUDINI_OTLSCAN_PATH values in a way that is backward compatible (since HOUDINI_OTL_PATH used to mean what HOUDINI_OPLIBRARIES_PATH now means).

  • HOUDINI_OTLSCAN_PATH

    This path specifies the directories Houdini will search for OTL files. This value is only used if the Operator Type Manager is configured not to use OPlibraries files to find OTL files. The default for this value is the HOUDINI_OTL_PATH with /otls appended to each directory in that path.

  • HOUDINI_OPLIBRARIES_PATH

    The path of directories where Houdini looks for OPlibraries files for loading OTL files at startup. OPlibraries files are only used if the Operator Type Manager is configured to use them. Otherwise OTL files are scanned for directly. This path by default is equal to the HOUDINI_OTL_PATH.

  • HOUDINI_SCRIPT_PATH

    The path of directories where Houdini searches for scripts. This includes .cmd files for hscript, .class files for the java command, .tcl and .tk files for the tcl and tk commands, and command scripts for the Alfred Output Driver.

  • HOUDINI_SOHO_PATH

    The path of directories used by soho.

  • HOUDINI_CLIP_PATH

    The path of directories where Houdini looks for .clip and .bclip channel files

  • HOUDINI_CUSTOM_PATH

    The path of directories where Houdini looks for custom panel information.

  • HOUDINI_DESK_PATH

    The path of directories where Houdini looks for desktops.

  • HOUDINI_DSO_PATH

    The search path for loading custom plug-ins (Dynamic Shared Objects or Dynamic Link Libraries).

  • HOUDINI_IMAGE_DSO_PATH

    The search path for loading custom image format plugins for reading and writing images of that format (.so, .dll).

  • HOUDINI_AUDIO_DSO_PATH

    The search path for loading custom audio format plugins for reading and writing audio or channel files (.so, .dll).

  • HOUDINI_PDG_DSO_PATH

    The search path for loading custom PDG node, work item, and scheduler definitions (.so, .dll).

  • HOUDINI_VEX_DSO_PATH

    The search path for loading custom VEX functions.

  • MANTRA_DSO_PATH

    The search path for loading mantra specific plug-ins (procedurals)

  • HOUDINI_ENABLE_OLD_PRESETS

    If set, the preset menu in the parameter pane toolbar will show the old-style presets options for loading and saving the presets to a file.

  • HOUDINI_USE_OTL_AS_DEFAULT_HDA_EXT

    If set, Houdini will use the older .otl as the default extension for digital assets instead of the newer .hda extension.

    This can be useful when using a legacy asset management system that does not yet understand the new .hda extension.

  • HOUDINI_GEOMETRY_PATH

    The search path for geometry files.

  • HOUDINI_GEOMETRY_CACHESIZE

    The size for caching of tessellated geometry in Houdini. Some uses for tessellated geometry include viewport rendering, and ray intersections.

  • HOUDINI_MACRO_PATH

    The search path for toolbar macro files.

  • HOUDINI_MENU_PATH

    The search path for XML menu files, such as the main menu, the node RMB menu, parameter menu, and shelf menu.

    Note, the paths are scanned in reverse order, i.e., the files from directories further in the path are loaded first, and files from directories earlier in the path are loaded later. This ensures that the default menus are loaded first, which allows custom files to modify their configuration.

  • HOUDINI_PDG_PATH

    The search path for PDG templates, interface files and custom Python node definitions.

  • HOUDINI_PYTHON_PANEL_PATH

    The search path for factory and custom Python panel files. The panel files are searched for and loaded when Houdini starts. They can define interfaces that appear in Python Panels or set the configuration of the Python Panel interfaces menu.

  • HOUDINI_TEXTURE_PATH

    The search path for loading images. This includes .rat files and other 2D formats as well as .i3d 3D texture files.

  • HOUDINI_TOOLBAR_PATH

    The search path for factory and custom shelves and shelf tools (i.e., shelf files). The shelf files are searched for and loaded when Houdini starts. They can define new tools that appear in the TAB menu or new groupings of tools (ie, toolbars or shelves) which can be displayed in the shelving area (usually, just below the main menu).

  • HOUDINI_RADIALMENU_PATH

    The search path for factory and custom radial menus. The radial menu files are searched for and loaded when Houdini starts.

  • HOUDINI_UI_APP_PATH

    An application search path for .ui definition files. Use care when changing this path, otherwise the graphical Houdini applications may not start.

  • HOUDINI_UI_AUDIO_PATH

    An application search path for the audio notification files used by the interface. Use care in changing this path, otherwise audio notifications may stop working.

  • HOUDINI_UI_CURSOR_PATH

    An application search path for locating the Houdini mouse cursor set. Use care when changing this path, otherwise the mouse cursor may not reflect its current context.

  • HOUDINI_UI_DIALOG_PATH

    An application search path for locating the Houdini dialog files generated from states, handles, operators and HDAs. Use care when changing this path, otherwise the parameter pane will not show any user interface for the chosen objects.

  • HOUDINI_UI_PATH

    The base path for all user interface files. Use extreme care when changing this variable, or graphical Houdini applications may not start. Before adding paths to this variable, check the other HOUDINI_UI variables to see if one or more of those paths will accomplish what you need. Adding a new path to this variable can be expensive.

  • HOUDINI_UI_TEMPLATE_PATH

    An application search path for locating the parts Houdini uses to compose a user interface for states, handles, operators and HDAs. Use extreme care when changing this path. Houdini may not recover very well if the user interface parts are missing.

  • HOUDINI_UI_ICON_PATH

    The search path for icon files. Setting this path will override the default of $HOUDINI_PATH/config/Icons.

  • HOUDINI_GEOMETRY_FORMAT

    Specifies the default geometry format used when saving geometry. The default is to use the current version of Houdini’s version. Setting to "hclassic" will save geometry in Houdini 11's geometry format, which doesn’t support all the features of later formats.

  • HOUDINI_ICON_CACHE_DIR

    The directory to store the cache of rendered icons in. By default, this cache is stored in $HOUDINI_USER_PREF_DIR/config/Icons. If your home directory is slow (for example, if home directories are stored on networked servers), setting this to a local path may help Houdini’s startup time.

  • HOUDINI_VEX_PATH

    The search path for VEX code. Setting this path will override the default path of $HOUDINI_PATH/vex/. Searching for the dialog scripts is independent of VEX searching and is controlled by the HOUDINI_PATH.

  • HOUDINI_GLSL_PATH

    The search path for GLSL code. Setting this path will override the default path of $HOUDINI_PATH/ogl2/. Searching for the dialog scripts is independent of GLSL searching and is controlled by the HOUDINI_PATH.

  • HOUDINI_ASSET_STORE_PATH

    The search path for the user’s asset store related files (asset OTLs, licenses, list of installed assets, etc)

  • HOUDINI_OUTLINEFONT_PATH

    This is the path searched for Adobe Type 1 or True Type fonts used in the Font SOP and Font COP.

  • HOUDINI_BACKUP_DIR

    This is the directory used to store the backed-up hip files when the "Numbered Backup" save option is set. HOUDINI_BACKUP_DIR must be set to a native file path. Custom file system (FS) paths are not supported.

  • HOUDINI_BACKUP_FILENAME

    A template for the filename used for file backups when the "Numbered Backup" save option is set. Two variables are required: $BASENAME, which will be replaced by the name of the file being saved without its extension; and $N, which is replaced by the backup number. $N can be followed by a single digit which is interpreted as the number of digits to be used in the backup number; numbers with fewer digits than this will be padded with zeroes. Default value is $BASENAME_bak$N.

    A subdirectory path may be included, but only $BASENAME will be replaced in this part of the template. This may be used to group all the backups for a given file into a subdirectory (e.g. $BASENAME/$BASENAME_bak$N).

  • HOUDINI_AUTOSAVE_FILENAME

    A template for the filename used for auto save file backups when the "Numbered Backup" auto save option is set. Two variables are required: $BASENAME, which will be replaced by the name of the file being saved without its extension; and $N, which is replaced by the backup number. $N can be followed by a single digit which is interpreted as the number of digits to be used in the backup number; numbers with fewer digits than this will be padded with zeroes. Default value is $BASENAME_auto$N.

    A subdirectory path may be included, but only $BASENAME will be replaced in this part of the template. This may be used to group all the backups for a given file into a subdirectory (e.g. $BASENAME/$BASENAME_auto$N).

  • HOUDINI_MAX_BACKUP_FILES

    Setting this environment variable will limit the number of backup files Houdini creates when the "Numbered Backup" save option is set. Setting this environment variable to 0 will disable the limit and Houdini will write as many backup files as resources permit (default). Once the limit is reached, the file with the oldest numbered suffix in the filename will be deleted.

  • HOUDINI_NO_SPLASH

    Setting this environment variable will disable the Houdini splash screen from being displayed.

  • HOUDINI_SPLASH_MESSAGE

    Defines a custom message that will appear on the splash screen. Placing the three character string //n in this message will place a new line in the splash screen.

  • HOUDINI_SPLASH_FILE

    Defines a custom file to load for the splash screen. You may want to augment this with the HOUDINI_SPLASH_MESSAGE to write build-specific information.

  • HOUDINI_BUFFEREDSAVE

    When enabled .hip files are first saved to a memory buffer and then written to disk. This is useful when saving over the network from Windows 2000 machines, or other places where seeking to the network is expensive.

  • HOUDINI_VIEWERSTATE_PATH

    The search path for viewer state files. These are python files used for implementing viewer states. Houdini searches them at startup to register standard and user-defined viewer states. The registration of python viewer states is lazy, they are registered only when required.

  • HOUDINI4_COMPATIBILITY

    When this is enabled, some of the quirks of Houdini 4 are turned on. This is designed to be used to allow old hip files to be loaded. Support for these inconsistencies is not guaranteed in future versions of Houdini. Currently, this will:

    • Change the order of points in Spheres, Tubes, Torii, and Circles under certain orientations.

    • Reverse the direction of the Clip SOP’s "distance" parameter.

    • Revert to the old capture region weighting method

  • HOUDINI55_COMPATIBILITY

    When this is enabled, some of the quirks of Houdini 5.5 (and earlier) are turned on. This is designed to allow old hip files to be loaded identically. Support for these inconsistencies are not guaranteed in future versions of Houdini. Currently, this will:

    • Not always use the shortest path rotation blending the PolyWire SOP and Composite CHOP

    • Revert to the old boneangle() behavior of calculating the angle between the two negative z axes of the given bones (Note that usually this expression would have been used as (180-boneangle(…)) which can easily be converted into the new behavior by no longer subtracting from 180)

    • The Switch Operators in POPs, SOPs, COP2s and SHOPs will not consolidate null inputs.

    • When globbing channel patterns, the order will be reverted back to reverse creation order. This affects the Fetch CHOP, and the following hscript commands: chls, chread, chwrite

    • The "tmgls -l" hscript command will revert to showing paths that start with /Director.

    • Revert to the old behavior where when Houdini is told to look at something with an up vector that is parallel to the target direction, we do nothing. This affects all of Houdini. This includes (but not limited to) the Look At parameter in all operators, the mlookat() expression function, and the lookat() VEX function.

  • HOUDINI6_COMPATIBILITY

    When this is enabled, some of the quirks of Houdini 6.0 (and earlier) are turned on. This is designed to be used to allow old hip files to be loaded identically. Support for these inconsistencies are not guaranteed in future versions of Houdini. Currently, this will:

    • With soft transforms (SoftPeak, SoftTransform, and Soft Options in the Edit SOP that are not applied) and Ignore Connectivity Off, connectivity does not respect the soft radius. In Houdini 6.1 and later, two points are connected only if there is a sequence of edges within the soft radius that connects them. In 6.0 and earlier, or with this flag on, they are connected if there is any sequence of edges that connects them.

    • The Fetch CHOP will create the order of its fetched tracks in the following order:

      • animated channels (in the parameter order of fetched operator)

      • chop data tracks

      • non-animated parameters (again in parameter order)

    • The Edit SOP will use an old method for determining how a surface changes relative to the rest input.

  • HOUDINI7_COMPATIBILITY

    When this is enabled, some of the quirks of Houdini 7.0 (and earlier) are turned on. This is designed to be used to allow old hip files to be loaded identically. Support for these inconsistencies are not guaranteed in future versions of Houdini. Currently, this will:

    • The Object CHOP has a parameter Compute whose value Single Bearing Angle measures an angle between +z axis and the direction vector from source to target object. This angle was incorrectly decremented by 90 degrees in earlier versions. Right now, when a target object is right ahead of the source (measuring along z-axis), the angle is correctly computed as 0 instead of -90 which would be the case in Houdini 7.0.

  • HOUDINI8_COMPATIBILITY

    When this is enabled, some of the quirks of Houdini 8.0 (and earlier) are turned on. This is designed to be used to allow old hip files to be loaded identically. Support for these inconsistencies are not guaranteed in future versions of Houdini. Currently, this will:

    • The global VOP variable list will include the illuminance global variables on only on nodes that are direct children of Illuminance VOPs. That is, the variables of deeply nested children will not be taken into consideration. Though omitting such variables is technically wrong, adding the illuminance variables to all child nodes of any depth would mess up the variable order and break existing VOP Networks.

    • The csh-style variable modifiers will be disabled. Normally, Houdini uses csh-style modifiers to expand variables for hscript and houdini. For example, for variable value of ryan.cmd, $var:r returns "ryan".

  • HOUDINI95_COMPATIBILITY

    When this is enabled, some of the quirks of Houdini 9.5 (and earlier) are turned on. This is designed to be used to allow old hip files to be loaded identically. Support for these inconsistencies are not guaranteed in future versions of Houdini. Currently, this will:

    • The Transform CHOP will use the old (incorrect) interpretation of the Transform Order parameters.

  • HOUDINI10_COMPATIBILITY

    When this is enabled, some of the backwards compatibility issues of Houdini 10.0 (and earlier) are turned on. This is designed to allow old hip files to be loaded identically in later versions. Support for these inconsistencies are not guaranteed in future versions of Houdini. Currently, this will:

    • Provide old behavior of the cycle(), cyclet() hscript expressions and HOM functions.

  • HOUDINI11_COMPATIBILITY

    When this is enabled, some of the backwards compatibility issues of Houdini 11.0 (and earlier) are turned on. This is designed to allow old hip files to be loaded identically in later versions. Support for these inconsistencies are not guaranteed in future versions of Houdini. Currently, this will:

    • Patterns matching deprecated capture attributes names can match the modern capture attributes in the Attribute Transfer SOP and Attribute Composite SOP.

    • The unix command will default to running csh instead of the value in the $SHELL variable.

    • The operator type name specified for node creation will be used exactly as is, without optype namespace or version lookup. This is equivalent of always specifying -e for opadd or passing true as exact_type to hou.Node.createNode(). It allows scripts generated by opscript in H11 to always recreate exact node network, even if there are newer versions of some operators.

  • HOUDINI11_PERFMON_COMPATIBILITY

    When this is enabled, clicking on the Windows > Performance Monitor menu entry will open the performance monitor that was available in Houdini 11.1 and earlier versions. The 11.1 performance monitor also supplies performance data to the node information tooltip window (i.e. a node).

  • HOUDINI10_VOLUME_COMPATIBILITY

    When this is enabled the .bgeo saving of volumes will use the untiled format compatible with early versions of 10.0 and earlier versions of Houdini.

  • HOUDINI13_VOLUME_COMPATIBILITY

    This setting will turn off saving of shared data for volume primitives. When this is enabled geometry files may be significantly larger and sharing information will be lost when re-loading geometry. This usually only impacts geometry that has multiple copies of the same volume primitive.

  • HOUDINI13_GEO_COMPATIBILITY

    This setting will enable the saving of .geo/.bgeo files compatible with 13.0 versions of Houdini. See also HOUDINI13_VOLUME_COMPATIBILITY.

  • HOUDINI14_GEO_COMPATIBILITY

    This setting will enable the saving of .geo/.bgeo files compatible with 14.0 versions of Houdini. If this is not set, packed geometry primitives will not be loaded properly.

  • HOUDINI15_PARMDATA_COMPATIBILITY

    This setting will enable the saving of geometry parameter data in a fashion compatible with early 15.0 and 15.5 versions of Houdini.

  • HOUDINI15_5_GEO_COMPATIBILITY

    This setting will enable the saving of .geo/.bgeo files compatible with 15.5 versions of Houdini. If this is not set, files with polygons or tetrahedra saved in Houdini 16.0 or later will not be loaded properly in Houdini 15.5 or earlier.

  • HOUDINI16_5_DEFORM_COMPATIBILITY

    This setting will enable the old bone deform algorithm that allowed for separately deforming the two ends of capture regions by animating their end caps.

  • HOUDINI6_FILTER_COMPATIBILITY

    There was a large bug found in the low level filtering code in Houdini6.1. Fixing this bug caused the results of filtering to change quite dramatically from previous versions. To maintain previous behavior, this control can be set. However, use of this control is discouraged since the filtering was incorrect before the fix. This control may be removed in future versions of Houdini.

  • HOUDINI13_FILTER_COMPATIBILITY

    There was a large bug found in the mip-map computations for texturing in Houdini13. Fixing this bug caused the results of filtering mip maps to change quite dramatically from previous versions. To maintain previous behavior, this control can be set. However, use of this control is discouraged since the filtering was incorrect before the fix. This control may be removed in future versions of Houdini.

  • HOUDINI_SIMPLIFIED_NODE_NAMES

    When this is enabled, node names are not permitted to have . or - characters in them. By default these characters are allowed.

  • HOUDINI_HIPEXT

    When this variable is set, Houdini will no longer add the .hip extension from the Save dialog. This also controls the addition of .otl and .bgeo extensions in the relevant save dialogs.

  • HOUDINI_ACCESS_METHOD

    This value can be 0 (the default), 1, or 2. It selects the method used by Houdini to check file and directory permissions under Windows. 0 checks the permissions of the current user against the Windows user and group permissions set for the file in question. This method may be slow on machines that use a network login server. 1 uses a different method for checking the Windows user and group permissions, but relies on functionality that is broken in Windows 2000 Service Pack 2. Method 2 simply checks the file attributes. This method is fast, but ignores the user and group permissions, and so may report that some files or directories can be written to when actually they cannot.

  • HOUDINI_COOK_MODE_THRESHOLD

    Setting this variable will set a safety limit (in Megabytes) for the memory consumption of Houdini. If Houdini goes over this memory limit, it will immediately switch into the "Never" cook mode and alert the user. Setting this environment variable to 0 will disable this feature. This setting is only necessary when running on 32-bit operating systems.

  • HSCRIPT_SAFEQUIT

    If this variable is set, the quit command in hscript will prompt the user to verify that they want to quit.

  • HSCRIPT_ALLOW_BACKGROUND_RENDER

    By default, hbatch will force renders to block hbatch until the render is complete. Setting this variable will allow hbatch to render in the background.

  • HOUDINI_OLD_RATS

    This variable controls the format for RAT file textures that will be generated by Houdini. When it is set to 0, the new TBF file format will be used. When set to 1, the old RAT format will be used. The default value for this option is 0. In general, TBF textures will have better performance, so this variable should only be enabled when a texture must be compatible with versions of Houdini prior to version 8.0.

  • HOUDINI_QTML_USE_GDI

    This variable is used to tell QuickTime to use GDI instead of DirectDraw or DCI on windows platforms. GDI is forced when set to 1, and QuickTime makes the decision when set to 0. The default value for this option is 1 to avoid crashes in QuickTime dialog components that seem to be related to some nvidia drivers.

  • HOUDINI_MAX_CACHED_FBX_SCENES

    Sets the maximum number of cached FBX scenes to keep in memory. Useful in scenes that link to multiple FBX files on disk to avoid reloading complete files every time a node cooks. The default value is 1, the minimum is 0, and the maximum is 20.

  • HOUDINI_NETEXCHANGE_HEARTBEAT

    When a distributed simulation is exchanging data with other nodes it will often block while waiting for the other nodes to catch up. During this time the process can appear dead because it is no longer using any CPU. When this heartbeat is a non-zero positive value, it represents the number of seconds between printing out heartbeats to standard out, thereby reminding the world that this process is still alive.

  • HOUDINI_DOPVOLUME_NANTEST

    When enabled the various DOP gas micro solvers will scan their fields for NANs before and after processing. This can be useful for finding where these numbers are showing up in a simulation. It is helpful to set perfmon -o stdout first so one can tell which micro-solver is operating when the NaN test outputs an error.

  • HOUDINI_MULTITHREADED_COOKING

    EXPERIMENTAL: When enabled, Houdini will attempt to perform multithreaded node cooking where possible. As of Houdini 11, cooking problems can occur such as deadlocks if enabled. Note that this environment setting currently does NOT affect anything other than viewport object cooking.

  • HOUDINI_OGL_FIXEDVOXELSIZE

    Instead of scaling the density of voxels in volumes by their size, all voxels are treated as if they were 1×1×1 cubes when computing opacity for display. This results in things appearing more opaque if they are higher resolution.

  • HOUDINI_OCL_VENDOR

    Specifies the platform vendor to choose when creating the OpenCL context Houdini uses for OpenCL processing.

  • HOUDINI_OCL_DEVICETYPE

    Specifies the type of OpenCL device to use for OpenCL processing. The choices are GPU and CPU. If HOUDINI_OCL_VENDOR is set, then once a platform vendor is identified, only devices of the specified type will be used. If HOUDINI_OCL_VENDOR is not set, then all available OpenCL platforms will be searched and the first device of the specified type returned. Setting this variable is therefore and easy way to switch devices.

  • HOUDINI_OCL_DEVICENUMBER

    In the case of multiple OpenCL devices existing of the type specified by HOUDINI_OCL_DEVICETYPE, this variable selects which of these devices to use for OpenCL processing. For example, with a computer with more than one GPU this allows selection of a GPU other than the default for OpenCL.

  • HOUDINI_OCL_PATH

    The search path for OpenCL kernels. Setting this path will override the default path of $HOUDINI_PATH/ocl/.

  • HOUDINI_OCL_MEMORY_POOL_SIZE

    Houdini uses a memory pool for allocating device memory through OpenCL for improved performance and to decrease fragmentation. This variable is the percentage of total device memory to allocate for the pool. For example, the default setting of 0.125 will allocate 1/8 of device memory for the memory pool. Note that if the specified OpenCL device is 32-bit, the total device memory is clamped to 4GB before being multiplied by this percentage.

  • HOUDINI_OCL_REPORT_MEMORY_USE

    When enabled, Houdini will output OpenCL memory usage statistics after every set of OpenCL kernel calls.

  • HOUDINI_IOBUFFER_SIZE

    The number of megabytes to spool into the background output thread before blocking the addition of new write tasks.

  • HOUDINI_DOP_MAXCACHE

    Sets a maximum DOP cache size in megabytes. Even if the DOP node has a cache size larger than this specified, it will be clamped by this amount. If negative (the default) no clamping is done.

  • HOUDINI_SOP_DISABLE_CACHENODE

    The Cache SOP is disabled if this option is set.

    NOTE: This may break networks that rely on caching, and/or greatly slow down networks by causing recooking where caching was used.

    It can be useful if Cache SOPs are only used for playblast and one wants to ensure a farm machine doesn’t accumulate memory.

  • HOUDINI_SOP_DISABLE_COMPILENODE

    The Block End Compile SOP will always be non-compiled if this is set.

    This is useful if you want to do performance testing to see differences between compiled and non-compiled settings, or rule out compiling as a source of a bug.

  • HOUDINI_RUN_IN_FOREGROUND

    If set to 1, Houdini GUI applications will by default run as a foreground application, if run form a shell or a terminal. Otherwise, GUI applications will put themselves in the background, no longer associated with the shell or terminal. This option has no effect on OSX.

  • HOUDINI_OGL_FAST_BONES

    When enabled, nulls and bones rendering is done by accumulating all the objects and issuing one instanced drawing call.

  • HOUDINI_FAST_SKIN_BLENDSHAPES

    Enable experimental feature to use the GPU to do deformation in SOP_Deform and SOP_BlendShapes.

  • HOUDINI_DISTRIBUTEDPROJECTION_DIAGNOSTICS

    Perform extra checks to verify distributed slices are building coherent projection matrices during distributed pressure solves. Turn this on if distributed solves are failing to converge to get extra diagnostic information to submit.

  • HOUDINI_SAS_DISABLE_ASSET_DOWNLOAD

    If set to 1, prevents graphical Houdini from downloading assets (i.e. Simple Toon Character) from Orbolt that are regularly installed in every Houdini distribution. Default is 0.

  • HOUDINI_USE_HFS_OCL

    Set to its default value of 1, this variable tells Houdini to load the built-in CPU OpenCL driver that is shipped in $HFS (64-bit Windows and Linux only). This built-in CPU device can be selected using the regular OpenCL device specifications, e.g. HOUDINI_OCL_DEVICETYPE=CPU.

    Houdini will also fall back to using this driver if the usual OpenCL device selection process fails, making it safer to submit OpenCL jobs to a renderfarm that has no GPUs. Set this variable to 2 to disable this fallback mechanism, or 0 to disable the built-in device completely.

    On OSX this variable has no effect.

  • HOUDINI_DISABLE_AUDIO_SERVER

    If set to 1, prevents the Audio Server from initializing. Default is 0.

  • QT_MOUSE_COMPRESS_LIMIT

    On Linux, Qt compresses mouse move events for improved performance. Compression works by issuing out a single mouse event to the application for a group of mouse events that occurred within a small time period. The downside to mouse event compression is that it diminishes the quality for operations that track mouse movement (i.e. drawing curves in the viewport). This is why Houdini disables mouse event compression by default.

    You can turn compression back on by setting QT_MOUSE_COMPRESS_LIMIT to a non-zero, integer value. The value represents the maximum number of mouse move events to be compressed for each compression run. The higher the limit the more compression that is allowed.

    Set this variable only if you are experiencing slow response times when interacting with Houdini’s viewport or any interface in Houdini that tracks mouse movement (i.e. an OpenGL viewport written in PySide or PyQt).

    This variable affects only Linux.

  • HOUDINI_CHOP_MOTION_SAMPLES

    This variable overrides the Global Animation Settings CHOP Motion Samples value if the hchannel.pref file isn’t present. It can be use to increase the CHOP sampling rate for Constraints at render time.

  • HOUDINI_NVIDIA_OPTIX_DSO_PATH

    Defines the OptiX DSO search path. The existance of this variable also determines whether the IPR toolbox enables the denoise button or not.

  • HOUDINI_NVIDIA_OPTIX_DEVICENUMBER

    Device ID to use for OptiX denoiser. Use "hgpuinfo -o" to determine OptiX device IDs. Leave it undefined or -1 to use the first device.

  • PDGDIR

    This variable can be used in place of PDG_SHARED_ROOT to indicate the working directory of a PDG scheduler.

Reference

User interface

  • Menus

    Explains each of the items in the main menus.

  • Viewers

    Viewer pane types.

  • Panes

    Documents the options in various panes.

  • Windows

    Documents the options in various user interface windows.

Programming

  • Expression functions

    Expression functions let you compute the value of parameters.

  • Expression cookbook

    Tips and tricks for writing expressions to accomplish various effects.

  • Python Scripting

    How to script Houdini using Python and the Houdini Object Model.

  • VEX

    VEX is a high-performance expression language used in many places in Houdini, such as writing shaders.

  • HScript commands

    HScript is Houdini’s legacy scripting language.

Command line

Guru level